Subject: Re: Subduction Zone Question From: Dave Nelson davenn@............... Date: Tue, 01 Jan 2008 13:59:35 +1100 Hi Jerry, happy New Year to you too Good questions you pose ... the angle of subduction does vary a bit in different locations The SW of the South Island of New Zealand is is almost vertical under the North Island , NZ it is much shallower ~ 30deg give or take a few deg (just a couple of examples) An easy way to determine how far horizontally they go before melting is to look at what is happening at the surface .... look for ranges of volcanoes ie. the Cascades in NW USA, the central North Island, NZ, volcanoes The volcanoes of the Andes in Sth America, the strings of volcanoes along the islands of Sumatera and Java in Indonesia, the volcanic island chain of the Aleutians etc etc you get the picture :) www.sydneystormcity.com/Nth_is_x.bmp <--- a quick North Is, NZ cross-section Yellowstone is a Hot Spot (correct term) as is Hawaii they are not related to subduction they are a mantle plume that ongoing reguardless of the plate motion going on above them. Look at seabed maps of the Pacific Basin and you can see many strings of islands, atolls and seamounts that indicate past and current Hot Spot activity. A more interesting study is the depth to which the descending slab goes before it melts. and one of the deepest areas for this is in the Tonga - Kermadec Trench in the South Pacific between Fiji and New Zealand. The depth to which the slab descends is directly related to the rate of plate motion in a given region. and in the T - K Trench you get quakes regularly to in excess of 600km, but horizontally maybe only a few 10's of km (20 - 100km) away from the trench. Plate motion here is ~ 7 - 8 cm/yr and decreases as you head south from the Fiji end of the zone towards the North Is of NZ. I could go into the why's of that but thats another whole lesson in itself. The faster the plate is moving, the faster the subduction, therefore the deeper the slab will descend before it melts. Another interesting effect is in this region .... the type of quakes occurring at the great depth. Picture a subducting slab 10km thick, the norm for the seafloor. and you can imagine as it starts to subduct its cold (relativey speaking) but as it subducts it starts to heat up from the outer layers towards its centre. But because of the high speed of subduction (plate motion), the core of the slab stays cold for a very long time ie. there is very high temperature differential across the slab. This results in many tremors within the slab as it internally fractures rather than events just between the surface of the slab and the surrounding rock its grinding past. Here's a project for you ..... and you can do it for any subduction zone Plot earthquakes (from the USGS/NEIC records) on a graph showing depth Vs distance from the trench line. (ie a cross-section across the subduction zone) and it easily show you 1) .. the angle of subduction, 2) the distance from the trench the subduction zone extends. Now b4 everyone screams its already been done with Alan Jones's seismic prog, why repeat it ? yes I know it has. But to actually do the exercise yourself and plot the data from the seismicity records for a given region. It gives you a ( I believe) a better insight and understanding into the processes going on :) cheers all Dave Nelson Sydney At 02:17 AM 01/01/2008, you wrote: >Hi All, >Happy New Year. >I have a question about Subduction Zones and their angle of incidence down >to the mantle. If I remember correctly, the Mariana Trench is quite steep >while others are not. >I was wondering specifically about the Pacific and Juan de Fuca plates and >their subduction angle under the Cascade Mountains. Specifically, I am >wondering how far the subduction angel goes inland before it melts into >the mantle? >The 3.8 event at the Yellowstone Park area brought the question to >mind. I know there is supposed to be a Hot Pocket under that area and >potentially explosive, but I was wondering if the subduction wedge >extended inland that far. Truthfully, I don't know how far Yellowstone is >from the coast. > >Of course, the farther inland, the deeper the wedge would be. The >Yellowstone event was shallow (6.8 km), and obviously not what I an asking >about. Nevertheless, I was wondering about that specific area >anyway. Anybody know? > >What the heck do you have to think about anyway, New Years parties? > >Regards, >Jerry > > >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.5.516 / Virus Database: 269.17.12/1203 - Release Date: >12/30/2007 11:27 AM __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Subduction Zone Question From: "Jerry Payton" gpayton880@....... Date: Mon, 31 Dec 2007 21:12:21 -0600 EXCELLENT answer Dave. You have the knack of explaining that I truly appreciate. I knew my question was overly simplistic and the answer complex and different for varied locals. You did a great job, thanks. Regarding your assignment, yes that is a good way to visualize the angle. I've read paragraphs and seen drawings on just that subject. Best Wishes in 2008, Jerry
EXCELLENT answer Dave. You have the knack of explaining = that I=20 truly appreciate.  I knew my question was overly simplistic and the = answer=20 complex and different for varied locals.  You did a = great=20 job, thanks.
 
Regarding your assignment, yes that is a good way to visualize the=20 angle.  I've read paragraphs and seen drawings on just that = subject.
 
Best Wishes in 2008,
Jerry
 
Subject: First STUPID Question of the New Year? From: "Jerry Payton" gpayton880@....... Date: Tue, 1 Jan 2008 15:14:55 -0600 OK, lets start out the new year with a simple question for the group showing MY ignorance and lack of training! I fully understand the theory and principle behind the Shadow Zones, but determining what MY shadow zones would be is confusing to me. Has anyone built a windows software program to calculate what the shadow zones would be given my Lat / Long coordinates? I understand the 104-140 degree zone that used, but I cannot correlate that into a spot or spots on the globe or map. Can someone please point me in the right direction to solving this, please. (If needed, my coordinates are 36.09N 094.13W.) Jerry
OK, lets start out the new year with a simple question for the = group=20 showing MY ignorance and lack of training!
 
I fully understand the theory and principle behind the Shadow = Zones,=20 but determining what MY shadow zones would be is confusing to me.  = Has=20 anyone built a windows software program to calculate what the shadow = zones would=20 be given my Lat / Long coordinates?
 
I understand the 104-140 degree zone that used, but I cannot = correlate that=20 into a spot or spots on the globe or map.  Can someone please point = me in=20 the right direction to solving this, please.
 
(If needed, my coordinates are 36.09N  094.13W.)
 
Jerry
Subject: Re: First STUPID Question of the New Year? From: tchannel1@............ Date: Tue, 1 Jan 2008 15:52:01 -0700 Happy New Year Everyone,=20 Jerry, This might help: If you have a globe, I have a 12" dia. = globe, you could compute the two different (P wave shadow zone at = 103-143 degrees) and the (S zone at 103-180 degrees,) into inches of the = surface of your globe. For a 12" globe, one degree=3D .104 inches. = 103 degrees=3D 10.712 inches. =20 Using the appropriate length of string, place one end on your home town = and using the other end of the string you could trace or otherwise mark = its length all around the globe. This line would represent the = beginning of the 103 degree shadow zone. However, I think I saw a wed site which may do this, using your = Lat/Long, and those of the earthquake. Ted ----- Original Message -----=20 From: Jerry Payton=20 To: PSN-L=20 Sent: Tuesday, January 01, 2008 2:14 PM Subject: First STUPID Question of the New Year? OK, lets start out the new year with a simple question for the group = showing MY ignorance and lack of training! I fully understand the theory and principle behind the Shadow Zones, = but determining what MY shadow zones would be is confusing to me. Has = anyone built a windows software program to calculate what the shadow = zones would be given my Lat / Long coordinates? I understand the 104-140 degree zone that used, but I cannot correlate = that into a spot or spots on the globe or map. Can someone please point = me in the right direction to solving this, please. (If needed, my coordinates are 36.09N 094.13W.) Jerry
Happy New Year = Everyone, 
 
 Jerry,   This might=20 help:   If you have a globe, I have a 12" dia. globe, you = could=20 compute the two different (P wave shadow zone at 103-143 degrees) and=20 the (S zone at 103-180 degrees,) into inches of the surface of your = globe.    For a 12" globe, one degree=3D .104 = inches.  =20 103 degrees=3D 10.712 inches. 
Using the appropriate length of string, = place one=20 end on your home town and using the other end of the string you could = trace or=20 otherwise mark its length all around the globe.  This line would = represent=20 the beginning of the 103 degree shadow zone.
However, I think I saw a wed site which = may do=20 this, using your Lat/Long, and those of the earthquake.
Ted
----- Original Message -----
From:=20 Jerry = Payton=20
To: PSN-L
Sent: Tuesday, January 01, 2008 = 2:14=20 PM
Subject: First STUPID Question = of the New=20 Year?

OK, lets start out the new year with a simple question for the = group=20 showing MY ignorance and lack of training!
 
I fully understand the theory and principle behind the = Shadow Zones,=20 but determining what MY shadow zones would be is confusing to = me.  Has=20 anyone built a windows software program to calculate what the shadow = zones=20 would be given my Lat / Long coordinates?
 
I understand the 104-140 degree zone that used, but I cannot = correlate=20 that into a spot or spots on the globe or map.  Can someone = please point=20 me in the right direction to solving this, please.
 
(If needed, my coordinates are 36.09N  094.13W.)
 
Jerry
Subject: Re: First STUPID Question of the New Year? From: tchannel1@............ Date: Tue, 1 Jan 2008 15:52:01 -0700 Happy New Year Everyone,=20 Jerry, This might help: If you have a globe, I have a 12" dia. = globe, you could compute the two different (P wave shadow zone at = 103-143 degrees) and the (S zone at 103-180 degrees,) into inches of the = surface of your globe. For a 12" globe, one degree=3D .104 inches. = 103 degrees=3D 10.712 inches. =20 Using the appropriate length of string, place one end on your home town = and using the other end of the string you could trace or otherwise mark = its length all around the globe. This line would represent the = beginning of the 103 degree shadow zone. However, I think I saw a wed site which may do this, using your = Lat/Long, and those of the earthquake. Ted ----- Original Message -----=20 From: Jerry Payton=20 To: PSN-L=20 Sent: Tuesday, January 01, 2008 2:14 PM Subject: First STUPID Question of the New Year? OK, lets start out the new year with a simple question for the group = showing MY ignorance and lack of training! I fully understand the theory and principle behind the Shadow Zones, = but determining what MY shadow zones would be is confusing to me. Has = anyone built a windows software program to calculate what the shadow = zones would be given my Lat / Long coordinates? I understand the 104-140 degree zone that used, but I cannot correlate = that into a spot or spots on the globe or map. Can someone please point = me in the right direction to solving this, please. (If needed, my coordinates are 36.09N 094.13W.) Jerry
Happy New Year = Everyone, 
 
 Jerry,   This might=20 help:   If you have a globe, I have a 12" dia. globe, you = could=20 compute the two different (P wave shadow zone at 103-143 degrees) and=20 the (S zone at 103-180 degrees,) into inches of the surface of your = globe.    For a 12" globe, one degree=3D .104 = inches.  =20 103 degrees=3D 10.712 inches. 
Using the appropriate length of string, = place one=20 end on your home town and using the other end of the string you could = trace or=20 otherwise mark its length all around the globe.  This line would = represent=20 the beginning of the 103 degree shadow zone.
However, I think I saw a wed site which = may do=20 this, using your Lat/Long, and those of the earthquake.
Ted
----- Original Message -----
From:=20 Jerry = Payton=20
To: PSN-L
Sent: Tuesday, January 01, 2008 = 2:14=20 PM
Subject: First STUPID Question = of the New=20 Year?

OK, lets start out the new year with a simple question for the = group=20 showing MY ignorance and lack of training!
 
I fully understand the theory and principle behind the = Shadow Zones,=20 but determining what MY shadow zones would be is confusing to = me.  Has=20 anyone built a windows software program to calculate what the shadow = zones=20 would be given my Lat / Long coordinates?
 
I understand the 104-140 degree zone that used, but I cannot = correlate=20 that into a spot or spots on the globe or map.  Can someone = please point=20 me in the right direction to solving this, please.
 
(If needed, my coordinates are 36.09N  094.13W.)
 
Jerry
Subject: Re: First STUPID Question of the New Year? From: "Jerry Payton" gpayton880@....... Date: Tue, 1 Jan 2008 17:33:28 -0600 That's one of my problems. I don't have a globe of any size. And, they cost soooo much for reasonably sized globes. I assume that you determine the correct length of the string and then just "scribe" a line around the globe and everything with that area is excluded, theoretically? Jerry ----- Original Message ----- From: tchannel1@............ To: psn-l@.............. Sent: Tuesday, January 01, 2008 4:52 PM Subject: Re: First STUPID Question of the New Year? Happy New Year Everyone, Jerry, This might help: If you have a globe, I have a 12" dia. globe, you could compute the two different (P wave shadow zone at 103-143 degrees) and the (S zone at 103-180 degrees,) into inches of the surface of your globe. For a 12" globe, one degree= .104 inches. 103 degrees= 10.712 inches. Using the appropriate length of string, place one end on your home town and using the other end of the string you could trace or otherwise mark its length all around the globe. This line would represent the beginning of the 103 degree shadow zone. However, I think I saw a wed site which may do this, using your Lat/Long, and those of the earthquake. Ted ----- Original Message ----- From: Jerry Payton To: PSN-L Sent: Tuesday, January 01, 2008 2:14 PM Subject: First STUPID Question of the New Year? OK, lets start out the new year with a simple question for the group showing MY ignorance and lack of training! I fully understand the theory and principle behind the Shadow Zones, but determining what MY shadow zones would be is confusing to me. Has anyone built a windows software program to calculate what the shadow zones would be given my Lat / Long coordinates? I understand the 104-140 degree zone that used, but I cannot correlate that into a spot or spots on the globe or map. Can someone please point me in the right direction to solving this, please. (If needed, my coordinates are 36.09N 094.13W.) Jerry
That's one of my problems.  I don't have a globe of any = size. =20 And, they cost soooo much for reasonably sized globes.  I assume = that you=20 determine the correct length of the string and then just "scribe" a line = around=20 the globe and everything with that area is excluded, = theoretically?
Jerry
 
 
----- Original Message -----=20
From: tchannel1@............
To: psn-l@..............
Sent: Tuesday, January 01, 2008 4:52 PM
Subject: Re: First STUPID Question of the New = Year?

Happy New Year = Everyone, 
 
 Jerry,   This might=20 help:   If you have a globe, I have a 12" dia. globe, you = could=20 compute the two different (P wave shadow zone at 103-143 degrees) and=20 the (S zone at 103-180 degrees,) into inches of the surface of your = globe.    For a 12" globe, one degree=3D .104 = inches.  =20 103 degrees=3D 10.712 inches. 
Using the appropriate length of string, = place one=20 end on your home town and using the other end of the string you could = trace or=20 otherwise mark its length all around the globe.  This line would = represent=20 the beginning of the 103 degree shadow zone.
However, I think I saw a wed site which = may do=20 this, using your Lat/Long, and those of the earthquake.
Ted
----- Original Message -----
From:=20 Jerry = Payton=20
To: PSN-L
Sent: Tuesday, January 01, 2008 = 2:14=20 PM
Subject: First STUPID Question = of the New=20 Year?

OK, lets start out the new year with a simple question for the = group=20 showing MY ignorance and lack of training!
 
I fully understand the theory and principle behind the = Shadow Zones,=20 but determining what MY shadow zones would be is confusing to = me.  Has=20 anyone built a windows software program to calculate what the shadow = zones=20 would be given my Lat / Long coordinates?
 
I understand the 104-140 degree zone that used, but I cannot = correlate=20 that into a spot or spots on the globe or map.  Can someone = please point=20 me in the right direction to solving this, please.
 
(If needed, my coordinates are 36.09N  094.13W.)
 
Jerry
Subject: How the earth moves From: tchannel1@............ Date: Fri, 4 Jan 2008 07:08:29 -0700 Happy New Year, Folks. When I receive an earthquake, the earth and my house are moved by the = event. The various phases moves the ground in different direction. This question has to do with the movement of the earth like that of a = teeter-totter. Tilt. like that measured by a level. 1. How much does the earth move? I do understand the earth would move = in many different directions, and move more, if the earthquake was = larger, and or closer. But somewhere I think I read some numbers indicating how much the earth = would be expected to move. I am asking this question, to help me understand, the approximate tilt = from an earthquake. If I hung a one meter pendulum, and a major = earthquake occurred 1000km away, the earth here, would tilt. If I were = looking at the pendulum at the moment the S wave arrived, assuming the = sensor was pointing in the correct direction, the pendulum would appear = to tilt, but unless the event was large enough I could not see it with = my eyes. If the event was large, I would be able to see it with my eyes. I saw the earth move during an earthquake 1993? I was at my kitchen = window felt or hear something, maybe the P,looked up, and maybe 4 = seconds later, I felt a wave, one up and one down. As I was looking = outside at the time I saw the wave move down the street. If I believed = my eyes. This wave was not 12", but it must have been more than 2". Anyhow I think you get the idea. 2. Completely different question: I would like to correspond with = someone who has used both AmaSeis and WinSDR. I know AmaSeis, but = would like to get some pointers on setting up WinSDR. =20 Thanks, Ted
Happy New Year, Folks.
 
When I receive an earthquake, the earth = and my=20 house are moved by the event.  The various phases moves the ground = in=20 different direction.
This question has to do with the = movement of the=20 earth like that of a teeter-totter.  Tilt. like that measured by a=20 level.
 
1.  How much does the earth = move?  I do=20 understand the earth would move in many different directions, and move = more, if=20 the earthquake was larger, and or closer.
But somewhere I think I read some = numbers=20 indicating how much the earth would be expected to move.
 
I am asking this question, to help me = understand,=20 the approximate tilt from an earthquake.   If I hung a one = meter=20 pendulum, and a major earthquake occurred 1000km away, the earth here, = would=20 tilt.  If I were looking at the pendulum at the moment the = S wave=20 arrived, assuming the sensor was pointing in the correct direction, the = pendulum=20 would appear to tilt, but unless the event was large enough I could not = see it=20 with my eyes.
If the event was large, I would be able = to see it=20 with my eyes.
 
I saw the earth move during an=20 earthquake 1993?   I was at my kitchen window felt or = hear=20 something, maybe the P,looked up, and maybe 4 seconds later, I felt a = wave, one=20 up and one down.  As I was looking outside at the time I saw the = wave move=20 down the street.   If I believed my eyes.  This wave was = not 12",=20 but it must have been more than 2".
 
Anyhow I think you get the = idea.
 
2. Completely different question:  = I would=20 like to correspond with someone who has used both AmaSeis and=20 WinSDR.   I know AmaSeis, but would like to get some pointers = on=20 setting up WinSDR. 
 
Thanks, Ted
Subject: Burning Questions From: "Jerry Payton" gpayton880@....... Date: Fri, 4 Jan 2008 09:22:45 -0600 While everyone has their "Thinking Caps" on from Ted's excellent questions, I have a couple that have been smoldering for some time: 1) Months ago I posted an event and I received an email commenting on it. He said, "It was very good, but I might try improving my P-wave." HOW does one "improve" one phase over another? It seems that the P-wave is always less stronger. 2) Much has been written about the length of a pendulum needing to be long to be effective for teleseismic detection. However, the commercial devices are quite compact and obviously have short pendulums. Can someone explain how they accomplish what they do with short pendulums? Thank you for "thinking for me." Jerry
While everyone has their "Thinking Caps" on from Ted's excellent = questions,=20 I have a couple that have been smoldering for some time:
 
1)    Months ago I posted an event and I received an = email=20 commenting on it.  He said, "It was very good, but I = might try=20 improving my P-wave."  HOW does one "improve" one phase over = another? =20 It seems that the P-wave is always less stronger.
 
2)    Much has been written about the length of a = pendulum=20 needing to be long to be effective for teleseismic detection.  = However, the=20 commercial devices are quite compact and obviously have short = pendulums. =20 Can someone explain how they accomplish what they do with short = pendulums?
 
Thank you for "thinking for me."
Jerry
 
 
Subject: Re: Burning Questions From: ChrisAtUpw@....... Date: Fri, 4 Jan 2008 11:41:22 EST In a message dated 04/01/2008, gpayton880@....... writes: While everyone has their "Thinking Caps" on from Ted's excellent questions, I have a couple that have been smoldering for some time: 1) Months ago I posted an event and I received an email commenting on it. He said, "It was very good, but I might try improving my P-wave." HOW does one "improve" one phase over another? It seems that the P-wave is always less stronger. Hi Jerry, I suggest that you ask him? Raw data files for the relevant time interval are normally submitted. It is usual to extract the digital trace and to then apply filters to it to make the waves more visible while doing your own analysis. You might set the HP and LP filters both to 1 second when searching for teleseismic P waves, for example. 2) Much has been written about the length of a pendulum needing to be long to be effective for teleseismic detection. However, the commercial devices are quite compact and obviously have short pendulums. Can someone explain how they accomplish what they do with short pendulums? They use very low noise capacitative detectors to get the very high resolution, to maybe well below 0.1 nano metre. The period may then be extended greatly by electronic feedback, or by digital feedback, or both. They may use small pendulums with a natural period of say 0.5 second or more, but these are totally controlled by the force feedback. Because direct position and not velocity is being measured, you get a fall off in the signal below resonance of only 1/f, not 1/f^2. You can extend a 'natural' 1 second system to over 1,000 seconds, but the electronics required to do this may be quite expensive. When I receive an earthquake, the earth and my house are moved by the event. The various phases move the ground in different directions. This question has to do with the movement of the earth like that of a teeter-totter. Tilt. like that measured by a level. 1. How much does the earth move? I do understand the earth would move in many different directions, and move more, if the earthquake was larger, and or closer. But somewhere I think I read some numbers indicating how much the earth would be expected to move. If you go to _http://jclahr.com/science/psn/magnitude.html_ (http://jclahr.com/science/psn/magnitude.html) you will find several graphs and tables. Remember that surface waves are often the largest in amplitude and that their amplitude is greatly effected by the local ground type. Waterlogged alluvial ground may behave very like a jelly. I am asking this question, to help me understand, the approximate tilt from an earthquake. If I hung a one meter pendulum, and a major earthquake occurred 1000km away, the earth here, would tilt. If I were looking at the pendulum at the moment the S wave arrived, assuming the sensor was pointing in the correct direction, the pendulum would appear to tilt, but unless the event was large enough I could not see it with my eyes. You need to remember the difference in response of a pendulum to both sideways motion and to direct tilts. S waves will show lateral motion, but P and Rayleigh waves may show direct tilt effects as well as motion. Regards, Chris Chapman
In a message dated 04/01/2008, gpayton880@....... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
While everyone has their "Thinking Caps" on from Ted's excellent=20 questions, I have a couple that have been smoldering for some time:
 
1)    Months ago I posted an event and I received an e= mail=20 commenting on it.  He said, "It was very good, but I might=20= try=20 improving my P-wave."  HOW does one "improve" one phase over=20 another?  It seems that the P-wave is always less=20 stronger.
Hi Jerry,
 
    I suggest that you ask him? Raw data files for=20= the=20 relevant time interval are normally submitted.
 
    It is usual to extract the digital trace and to= =20 then apply filters to it to make the waves more visible while doing your own= =20 analysis. You might set the HP and LP filters both to 1 second when searchin= g=20 for teleseismic P waves, for example.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
2)    Much has been written about the length of a pend= ulum=20 needing to be long to be effective for teleseismic detection.  Howeve= r,=20 the commercial devices are quite compact and obviously have short=20 pendulums.  Can someone explain how they accomplish what they do with= =20 short pendulums?
    They use very low noise capacitative detectors=20= to=20 get the very high resolution, to maybe well below 0.1 nano metre. The period= may=20 then be extended greatly by electronic feedback, or by digital feedback, or=20 both. They may use small pendulums with a natural period of say 0.5 second o= r=20 more, but these are totally controlled by the force feedback. Because direct= =20 position and not velocity is being measured, you get a fall off in the signa= l=20 below resonance of only 1/f, not 1/f^2. You can extend a 'natural' 1 second=20 system to over 1,000 seconds, but the electronics required to do this may be= =20 quite expensive.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
When I receive an earthquake, the earth a= nd my=20 house are moved by the event.  The various phases move the ground in=20 different directions. This question has= to do=20 with the movement of the earth like that of a teeter-totter.  Tilt. l= ike=20 that measured by a level.
 
1.  How much does the earth move?&nb= sp; I do=20 understand the earth would move in many different directions, and move mor= e,=20 if the earthquake was larger, and or closer. But somewhere I think I read some numbers indicating how much the= earth=20 would be expected to move.
    If you go to http://jclahr.com/scie= nce/psn/magnitude.html you=20 will find several graphs and tables. Remember that surface waves are often t= he=20 largest in amplitude and that their amplitude is greatly effected by the loc= al=20 ground type. Waterlogged alluvial ground may behave very like a jelly.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
I am asking this question, to help me und= erstand,=20 the approximate tilt from an earthquake.   If I hung a one meter= =20 pendulum, and a major earthquake occurred 1000km away, the earth here, wou= ld=20 tilt.  If I were looking at the pendulum at the moment the S wav= e=20 arrived, assuming the sensor was pointing in the correct direction, the=20 pendulum would appear to tilt, but unless the event was large enough I cou= ld=20 not see it with my eyes.
    You need to remember the difference in response= of=20 a pendulum to both sideways motion and to direct tilts. S waves will show=20 lateral motion,  but P and Rayleigh waves may show direct tilt effects=20= as=20 well as motion.
 
    Regards,
 
    Chris Chapman
Subject: Hekla volcano geophone planned From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 04 Jan 2008 17:03:55 +0000 Hi all I am going to setup a geophone close to the Hekla volcano this year (20 something km). I am going to speed up progress of setting up that geophone as I can, but at the latest the geophone is going up next summer. Hekla volcano is ready to erupt at any time. That is the reason for the speedup for that project. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: "Jerry Payton" gpayton880@....... Date: Fri, 4 Jan 2008 11:07:42 -0600 Jon, how in the world are you linking to all these geophones and back to your station?? 20 something km !!!??? Jerry ----- Original Message ----- From: Jón Frímann To: PSN-Postlist Sent: Friday, January 04, 2008 11:03 AM Subject: Hekla volcano geophone planned Hi all I am going to setup a geophone close to the Hekla volcano this year (20 something km). I am going to speed up progress of setting up that geophone as I can, but at the latest the geophone is going up next summer. Hekla volcano is ready to erupt at any time. That is the reason for the speedup for that project. Regards. -- Jón Frímann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Jon, how in the world are you linking to all these geophones = and=20  back to your station?? 20 something km !!!???
Jerry
 
 
----- Original Message -----=20
From: J=F3n = Fr=EDmann
To: PSN-Postlist
Sent: Friday, January 04, 2008 11:03 AM
Subject: Hekla volcano geophone planned

Hi all

I am going to setup a geophone close to the = Hekla=20 volcano this year (20
something km). I am going to speed up progress = of=20 setting up that
geophone as I can, but at the latest the geophone is = going up=20 next
summer.

Hekla volcano is ready to erupt at any time. That = is the=20 reason for the
speedup for that project.

Regards.
-- =
J=F3n=20 Fr=EDmann
http://www.jonfr.com
http://earthquakes.jonfr.comhttp://www.net303.net
http://www.mobile-coverage.com/<= /A>

__________________________________________________________
=
Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@............... with=20
the body of the message (first line only): unsubscribe
See http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: Hekla volcano geophone planned From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 04 Jan 2008 17:10:47 +0000 Hi The geophone is going to be located at a house that is ~20 km away from Hekla volcano. But the connection from there to my main computer I am going to use the internet. Regards.=20 --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: "Jerry Payton" gpayton880@....... Date: Fri, 4 Jan 2008 11:17:19 -0600 Hmmmm That's interesting, Jon. I'd like to know more how you accomplish that without a different IP address for each geophone that you use. You might contact me directly gpayton880@....... with an explanation and/or drawing when you have time. Regards, Jerry ----- Original Message ----- From: Jón Frímann To: psn-l@.............. Sent: Friday, January 04, 2008 11:10 AM Subject: Re: Hekla volcano geophone planned Hi The geophone is going to be located at a house that is ~20 km away from Hekla volcano. But the connection from there to my main computer I am going to use the internet. Regards. -- Jón Frímann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Hmmmm  That's interesting, Jon.  I'd like to know more = how you=20 accomplish that without a different IP address for each geophone that = you=20 use.  You might contact me directly  gpayton880@.......  with an=20 explanation and/or drawing when you have time.
Regards,
Jerry
 
 
----- Original Message -----=20
From: J=F3n = Fr=EDmann
Sent: Friday, January 04, 2008 11:10 AM
Subject: Re: Hekla volcano geophone planned

Hi

The geophone is going to be located at a house = that is=20 ~20 km away from
Hekla volcano. But the connection from there to my = main=20 computer I am
going to use the internet.

Regards.
-- =
J=F3n=20 Fr=EDmann
http://www.jonfr.com
http://earthquakes.jonfr.comhttp://www.net303.net
http://www.mobile-coverage.com/<= /A>

__________________________________________________________
=
Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@............... with=20
the body of the message (first line only): unsubscribe
See http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: RE: Hekla volcano geophone planned From: "Timothy Carpenter" geodynamics@....... Date: Fri, 4 Jan 2008 13:24:03 -0500 Jon & Jerry, I too would be interested in how you are setting up your internet connection(s) =96 so let=92s keep the discussion on-list. -Tim- Timothy Carpenter =20 From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Jerry Payton Sent: Friday, January 04, 2008 12:17 PM To: psn-l@.............. Subject: Re: Hekla volcano geophone planned =20 Hmmmm That's interesting, Jon. I'd like to know more how you = accomplish that without a different IP address for each geophone that you use. You might contact me directly gpayton880@....... with an explanation = and/or drawing when you have time. Regards, Jerry =20 =20 ----- Original Message -----=20 From: J=F3n Fr=EDmann =20 To: psn-l@................. Sent: Friday, January 04, 2008 11:10 AM Subject: Re: Hekla volcano geophone planned =20 Hi The geophone is going to be located at a house that is ~20 km away from Hekla volcano. But the connection from there to my main computer I am going to use the internet. Regards.=20 --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)

Jon & Jerry,

I too would be interested in how you are setting up your internet connection(s) – so let’s keep the discussion = on-list.

-Tim-

Timothy Carpenter

 

From:= psn-l-request@.............. [mailto:psn-l-request@............... On = Behalf Of Jerry Payton
Sent: Friday, January 04, 2008 12:17 PM
To: psn-l@..............
Subject: Re: Hekla volcano geophone planned

 

Hmmmm  That's interesting, Jon.  I'd like = to know more how you accomplish that without a different IP address for each = geophone that you use.  You might contact me directly  gpayton880@.......  with an explanation and/or drawing when you have time.

Regards,

Jerry

 

 

----- Original Message -----

Sent:<= /b> Friday, = January 04, 2008 11:10 AM

Subject: Re: Hekla = volcano geophone planned

 

Hi

The geophone is going to be located at a house that is ~20 km away = from
Hekla volcano. But the connection from there to my main computer I = am
going to use the internet.

Regards.
--
J=F3n Fr=EDmann
http://www.jonfr.com
http://earthquakes.jonfr.com http://www.net303.net
http://www.mobile-coverage.com/<= /a>

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@............... with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.co= m/maillist.html for more information.

Subject: RE: Hekla volcano geophone planned From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 04 Jan 2008 18:45:23 +0000 Hi I have a pc with each geophone. The internet is used to send me the data back to my main computer. It looks like this, Main PC (hvt station) --- Internet --- Hekla geophone+pc I try to use the internet connection that already there, rather then have to buy one on my own. I have used this type of setup already. The Mosfellsb=E6r station is connecteted in this way already. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Fri, 04 Jan 2008 20:28:53 +0000 Hi, to answer the question below, more than 1 data source per ip address, here's 2 approaches (many more no doubt are possible): tcp/ip sockets. Using these, each ip address can be split into 65536 channels, or sockets, 0 to 65535. Some of these are already allocated, like 25 for mail and 80 for web browsing. Anything above 1000 should be available but check or be alert to something no longer working and try another socket number. These are also what those nasty hacker creatures use for sneaking into unprotected pcs. You could have 1 socket per sensor. Under this regime you would need to have a server program running in the pc for each socket. It "listens" for incoming connections. When a connection request is made, it starts serving up the stream of data for that particular sensor. But rather than have 1 sensor on a single socket it is more sensible to have many sensors on a single socket using a data protocol. This is how I have designed my system. It sends out a continuous stream (50 samples per second) of "(Lehman reading) (geophone reading) (time stamp)". My graphing program makes a connection to the "data server" and plots the values from the 2 sensors as they arrive. See http://www.iasmith.com. As you'll see, my above-ground system is badly affected by wind. I recently achieved a big increase in sensitivity and was rewarded by the now increased significance of the wind :-( . I need to dig down and make a below-ground system. Segway to the next topic... Cheers Ian Jerry Payton wrote: > Hmmmm That's interesting, Jon. I'd like to know more how you > accomplish that without a different IP address for each geophone that > you use. You might contact me directly gpayton880@....... > with an explanation and/or drawing when > you have time. > Regards, > Jerry > > > ----- Original Message ----- > *From:* Jón Frímann > *To:* psn-l@.............. > *Sent:* Friday, January 04, 2008 11:10 AM > *Subject:* Re: Hekla volcano geophone planned > > Hi > > The geophone is going to be located at a house that is ~20 km away from > Hekla volcano. But the connection from there to my main computer I am > going to use the internet. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://earthquakes.jonfr.com > http://www.net303.net > http://www.mobile-coverage.com/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. > with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: "Jerry Payton" gpayton880@....... Date: Fri, 4 Jan 2008 15:48:56 -0600 Thank you Ian, Jon and Tim, All good answers. When I heard something new to me, my mind says, "Hmmm. Wonder how that works or how that is hooked up." I appreciate each input. Jerry ----- Original Message ----- From: ian To: psn-l@.............. Sent: Friday, January 04, 2008 2:28 PM Subject: Re: Hekla volcano geophone planned Hi, to answer the question below, more than 1 data source per ip address, here's 2 approaches (many more no doubt are possible): tcp/ip sockets. Using these, each ip address can be split into 65536 channels, or sockets, 0 to 65535. Some of these are already allocated, like 25 for mail and 80 for web browsing. Anything above 1000 should be available but check or be alert to something no longer working and try another socket number. These are also what those nasty hacker creatures use for sneaking into unprotected pcs. You could have 1 socket per sensor. Under this regime you would need to have a server program running in the pc for each socket. It "listens" for incoming connections. When a connection request is made, it starts serving up the stream of data for that particular sensor. But rather than have 1 sensor on a single socket it is more sensible to have many sensors on a single socket using a data protocol. This is how I have designed my system. It sends out a continuous stream (50 samples per second) of "(Lehman reading) (geophone reading) (time stamp)". My graphing program makes a connection to the "data server" and plots the values from the 2 sensors as they arrive. See http://www.iasmith.com. As you'll see, my above-ground system is badly affected by wind. I recently achieved a big increase in sensitivity and was rewarded by the now increased significance of the wind :-( . I need to dig down and make a below-ground system. Segway to the next topic... Cheers Ian Jerry Payton wrote: > Hmmmm That's interesting, Jon. I'd like to know more how you > accomplish that without a different IP address for each geophone that > you use. You might contact me directly gpayton880@....... > with an explanation and/or drawing when > you have time. > Regards, > Jerry > > > ----- Original Message ----- > *From:* Jón Frímann > *To:* psn-l@.............. > *Sent:* Friday, January 04, 2008 11:10 AM > *Subject:* Re: Hekla volcano geophone planned > > Hi > > The geophone is going to be located at a house that is ~20 km away from > Hekla volcano. But the connection from there to my main computer I am > going to use the internet. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://earthquakes.jonfr.com > http://www.net303.net > http://www.mobile-coverage.com/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. > with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Thank you Ian, Jon and Tim,
 
All good answers.  When I heard something new to me, my mind = says,=20 "Hmmm. Wonder how that works or how that is hooked up."  I = appreciate each=20 input.
Jerry
 
 
----- Original Message -----=20
From: ian
Sent: Friday, January 04, 2008 2:28 PM
Subject: Re: Hekla volcano geophone planned

Hi,

to answer the question below, more than 1 data = source=20 per ip address,
here's 2 approaches (many more no doubt are=20 possible):

tcp/ip sockets.  Using these, each ip address can = be=20 split into 65536
channels, or sockets, 0 to 65535.  Some of = these are=20 already allocated,
like 25 for mail and 80 for web browsing.  = Anything=20 above 1000 should be
available but check or be alert to something no = longer=20 working and try
another socket number.  These are also what = those nasty=20 hacker creatures
use for sneaking into unprotected pcs.

You = could=20 have 1 socket per sensor.  Under this regime you would need to =
have a=20 server program running in the pc for each socket.  It "listens" =
for=20 incoming connections.  When a connection request is made, it starts =
serving up the stream of data for that particular sensor.

But = rather=20 than have 1 sensor on a single socket it is more sensible to
have = many=20 sensors on a single socket using a data protocol.  This is how =
I have=20 designed my system.  It sends out a continuous stream (50 samples =
per=20 second) of "(Lehman reading) (geophone reading) (time stamp)".  My=20
graphing program makes a connection to the "data server" and plots = the=20
values from the 2 sensors as they arrive.  See http://www.iasmith.com.

As = you'll see,=20 my above-ground system is badly affected by wind.  I
recently = achieved=20 a big increase in sensitivity and was rewarded by the
now increased=20 significance of the wind  :-( .  I need to dig down and =
make a=20 below-ground system.  Segway to the next=20 topic...

Cheers

Ian



Jerry Payton = wrote:
>=20 Hmmmm  That's interesting, Jon.  I'd like to know more how you =
> accomplish that without a different IP address for each = geophone that=20
> you use.  You might contact me directly  gpayton880@.......
> = <mailto:gpayton880@.......> = ; with an=20 explanation and/or drawing when
> you have time.
> = Regards,
>=20 Jerry
> 
> 
> ----- Original Message = -----
>=20 *From:* J=F3n Fr=EDmann <mailto:jonfr@.........>
> = *To:* psn-l@.............. <mailto:psn-l@..............><= BR>>=20 *Sent:* Friday, January 04, 2008 11:10 AM
> *Subject:* Re: Hekla = volcano=20 geophone planned
>
> Hi
>
> The geophone is = going to be=20 located at a house that is ~20 km away from
> Hekla volcano. But = the=20 connection from there to my main computer I am
> going to use the=20 internet.
>
> Regards.
> --
> J=F3n = Fr=EDmann
> http://www.jonfr.com
> http://earthquakes.jonfr.com> http://www.net303.net
> http://www.mobile-coverage.com/<= /A>
>
>=20 __________________________________________________________
>
>= ;=20 Public Seismic Network Mailing List (PSN-L)
>
> To leave = this list=20 email PSN-L-REQUEST@............... =20
> <mailto:PSN-L-REQUEST@SEISMIC= NET.COM>=20 with
> the body of the message (first line only): = unsubscribe
> See=20 http://www.seismicnet.co= m/maillist.html=20 for more information.

--

<http://www.festivalpreviews.com<= /A>>
__________________________________________________________
=
Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@............... with=20
the body of the message (first line only): unsubscribe
See http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: Hekla volcano geophone planned From: ChrisAtUpw@....... Date: Sat, 5 Jan 2008 00:20:26 EST In a message dated 04/01/2008, gpayton880@....... writes: But rather than have 1 sensor on a single socket it is more sensible to have many sensors on a single socket using a data protocol. This is how I have designed my system. It sends out a continuous stream (50 samples per second) of "(Lehman reading) (geophone reading) (time stamp)". My graphing program makes a connection to the "data server" and plots the values from the 2 sensors as they arrive. See _http://www.iasmith.com_ (http://www.iasmith.com/) . Hi Ian, The limitation tends to be the total data throughput speed reqired. 50 SPS is quite fast. The ADC sample rate can also impose limitations. This starts to become serious when you have, say several three off three channel sensors on the same ADC. Regards, Chris Chapman
In a message dated 04/01/2008, gpayton880@....... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>But=20 rather than have 1 sensor on a single socket it is more sensible to
ha= ve=20 many sensors on a single socket using a data protocol.  This is how <= BR>I=20 have designed my system.  It sends out a continuous stream (50 sample= s=20
per second) of "(Lehman reading) (geophone reading) (time stamp)".&nbs= p;=20 My
graphing program makes a connection to the "data server" and plots=20= the=20
values from the 2 sensors as they arrive.  See http://www.iasmith.com.
Hi Ian,
 
    The limitation tends to be the total data=20 throughput speed reqired. 50 SPS is quite fast. The ADC sample rate can= =20 also impose limitations. This starts to become serious when you have, say=20 several three off three channel sensors on the same ADC.
 
    Regards,
 
    Chris Chapman
Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Sat, 05 Jan 2008 09:35:41 +0000 Hi, actually, I don't think I'm near any limits. The A/D I use can handle 20K samples/sec. I only have 2 instruments (though I sample each on 3 A/D channels to get the resolution up to 22 bits), so that's only 6 x 50, or 300 samples/sec. So I could connect up all of the A/D's 16 input channels and still not stress it. The data server does burn up 80% of the PC's CPU but it's only an old 800 MHz machine and wouldn't cost much to replace with one twice the speed. Data across the network connection is only 32 characters x 50 or 1600 bytes/sec. Less than a 500th of the 100 Mb/s network bandwidth (being generous). All of the above though, implies that you are happy to write your own code. Buying building blocks off the shelf can be very attractive. For multiple instruments you could buy several PSN A/D boards. To overcome the potential problem of connecting up multiple RS232 cables, you could use a network terminal server (such as http://www.perle.com/products/IOLAN-STS-Terminal-Server.shtml?rack ). These aggregate up to 4/8/16/24 rs232 connections on to one network connection. They usually come with software for the pc which creates multiple virtual COM ports, so your A/D boards would look like they are plugged into an array of COM ports on the PC. Isn't technology wonderful! Cheers Ian ChrisAtUpw@....... wrote: > In a message dated 04/01/2008, gpayton880@....... writes: > > But rather than have 1 sensor on a single socket it is more > sensible to > have many sensors on a single socket using a data protocol. This > is how > I have designed my system. It sends out a continuous stream (50 > samples > per second) of "(Lehman reading) (geophone reading) (time > stamp)". My > graphing program makes a connection to the "data server" and plots > the > values from the 2 sensors as they arrive. See > http://www.iasmith.com . > > Hi Ian, > > The limitation tends to be the total data throughput > speed reqired. 50 SPS is quite fast. The ADC sample rate can also > impose limitations. This starts to become serious when you have, say > several three off three channel sensors on the same ADC. > > Regards, > > Chris Chapman -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sat, 05 Jan 2008 11:28:55 +0000 Hi All of my remote sensors are going to be connected over the internet. I have ~6mb ADSL connection, so it should be able to handle it. The data flow isn't a lot, about ~100mb pr day on each station. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Large earthquake near cost of Canada From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sat, 05 Jan 2008 11:32:14 +0000 Hi all There appears to have been a large earthquake near the cost of Canada this morning (GMT time). I am unsure what the size is, but usgs is reporting M6.5 Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake near cost of Canada From: ian ian@........... Date: Sat, 05 Jan 2008 11:44:53 +0000 Hi, yes thanks, I can see it. It's a bit windy here, so my trace is not pristine... Cheers Ian http://www.iasmith.com http://www.festivalpreviews.com Jón Frímann wrote: > Hi all > > There appears to have been a large earthquake near the cost of Canada > this morning (GMT time). I am unsure what the size is, but usgs is > reporting M6.5 > > Regards. > -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake near cost of Canada From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sat, 05 Jan 2008 12:15:43 +0000 Hi At 11:44 GMT there was a second large earthquake near the east cost of Canada, USGS early size gives it M6.5. This is quite unusual for this area to have two earthquakes with this short period. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: Hekla volcano geophone planned From: Angel sismos@.............. Date: Sat, 5 Jan 2008 13:57:23 +0000 Hello Jon, Timothy and all, I would like this thread on the list also. Angel Friday, January 4, 2008, 6:24:03 PM, you wrote: > Jon & Jerry, > I too would be interested in how you are setting up your internet > connection(s) – so let’s keep the discussion on-list. > -Tim- > Timothy Carpenter > > From: psn-l-request@.............. > [mailto:psn-l-request@............... On Behalf Of Jerry Payton > Sent: Friday, January 04, 2008 12:17 PM > To: psn-l@.............. > Subject: Re: Hekla volcano geophone planned > > Hmmmm That's interesting, Jon. I'd like to know more how you > accomplish that without a different IP address for each geophone > that you use. You might contact me directly gpayton880@....... > with an explanation and/or drawing when you have time. > Regards, > Jerry > > > ----- Original Message ----- > From: Jón Frímann > To: psn-l@.............. > Sent: Friday, January 04, 2008 11:10 AM > Subject: Re: Hekla volcano geophone planned > > Hi > The geophone is going to be located at a house that is ~20 km away from > Hekla volcano. But the connection from there to my main computer I am > going to use the internet. > Regards. -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Burning Questions From: Brett Nordgren Brett3mr@............. Date: Sat, 05 Jan 2008 10:12:06 -0500 Jerry, re: 2) Almost all modern commercial sensors use some form of an astatic leaf-spring suspension. See fig. 10 of http://jclahr.com/science/psn/wielandt/node15.html With careful design and very careful adjustment, even quite a small pendulum (2") can be made to have a long free period. However, such a setup is very prone to drift from temperature and other changes and is only useful when it is combined with feedback such as Chris describes, to broaden its frequency response curve and stabilize its tendency to 'wander'. In such an instrument the real benefit of the long free period is to make it easier for the feedback to accurately control its motion. Long free period = low restoring force = less feedback force needed to control the pendulum. Brett At 09:22 AM 1/4/2008 -0600, you wrote: >While everyone has their "Thinking Caps" on from Ted's excellent >questions, I have a couple that have been smoldering for some time: > >1) Months ago I posted an event and I received an email commenting on >it. He said, "It was very good, but I might try improving my >P-wave." HOW does one "improve" one phase over another? It seems that >the P-wave is always less stronger. > >2) Much has been written about the length of a pendulum needing to be >long to be effective for teleseismic detection. However, the commercial >devices are quite compact and obviously have short pendulums. Can someone >explain how they accomplish what they do with short pendulums? > >Thank you for "thinking for me." >Jerry My e-mail address above should be working, but if not you can always use my mail form at: http://bnordgren.org/contactB.html using your Web browser. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: Hekla volcano geophone planned From: Angel sismos@.............. Date: Sat, 5 Jan 2008 15:39:15 +0000 Hello Ian, I have not read each messages of this thread careful but I will. All of the software needed to link a large distributed seismic system is free and freely available. Anyone who has one of Larry's 16 bit 8 channel boards with GPS (wwv) timing and a full time internet connection can share data and PSN can a global or regional system auto locating system. Angel Saturday, January 5, 2008, 9:35:41 AM, you wrote: > Hi, > actually, I don't think I'm near any limits. The A/D I use can handle > 20K samples/sec. I only have 2 instruments (though I sample each on 3 > A/D channels to get the resolution up to 22 bits), so that's only 6 x > 50, or 300 samples/sec. So I could connect up all of the A/D's 16 input > channels and still not stress it. > The data server does burn up 80% of the PC's CPU but it's only an old > 800 MHz machine and wouldn't cost much to replace with one twice the > speed. Data across the network connection is only 32 characters x 50 or > 1600 bytes/sec. Less than a 500th of the 100 Mb/s network bandwidth > (being generous). > All of the above though, implies that you are happy to write your own > code. Buying building blocks off the shelf can be very attractive. For > multiple instruments you could buy several PSN A/D boards. To overcome > the potential problem of connecting up multiple RS232 cables, you could > use a network terminal server (such as > http://www.perle.com/products/IOLAN-STS-Terminal-Server.shtml?rack ). > These aggregate up to 4/8/16/24 rs232 connections on to one network > connection. They usually come with software for the pc which creates > multiple virtual COM ports, so your A/D boards would look like they are > plugged into an array of COM ports on the PC. > Isn't technology wonderful! > Cheers > Ian > ChrisAtUpw@....... wrote: >> In a message dated 04/01/2008, gpayton880@....... writes: >> But rather than have 1 sensor on a single socket it is more >> sensible to >> have many sensors on a single socket using a data protocol. This >> is how >> I have designed my system. It sends out a continuous stream (50 >> samples >> per second) of "(Lehman reading) (geophone reading) (time >> stamp)". My >> graphing program makes a connection to the "data server" and plots >> the >> values from the 2 sensors as they arrive. See >> http://www.iasmith.com . >> Hi Ian, >> >> The limitation tends to be the total data throughput >> speed reqired. 50 SPS is quite fast. The ADC sample rate can also >> impose limitations. This starts to become serious when you have, say >> several three off three channel sensors on the same ADC. >> >> Regards, >> >> Chris Chapman -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Sat, 05 Jan 2008 15:57:40 +0000 Hi, yes, you're right, all free. I was really addressing the earlier (possibly hypothetical) question of how to connect many sensors to 1 network connection. The engineer in me probably made my response a bit enthusiastic and suitable for connecting dozens of sensors. Back to (free) reality! Cheers Ian http://www.iasmith.com/ http://www.festivalpreviews.com Angel wrote: > Hello Ian, > > I have not read each messages of this thread careful but I will. All of the software needed to link a large distributed seismic system is free and freely available. > > Anyone who has one of Larry's 16 bit 8 channel boards with GPS (wwv) timing and a full time internet connection can share data and PSN can a global or regional system auto locating system. > > Angel > > > > Saturday, January 5, 2008, 9:35:41 AM, you wrote: > > >> Hi, >> > > >> actually, I don't think I'm near any limits. The A/D I use can handle >> 20K samples/sec. I only have 2 instruments (though I sample each on 3 >> A/D channels to get the resolution up to 22 bits), so that's only 6 x >> 50, or 300 samples/sec. So I could connect up all of the A/D's 16 input >> channels and still not stress it. >> > > >> The data server does burn up 80% of the PC's CPU but it's only an old >> 800 MHz machine and wouldn't cost much to replace with one twice the >> speed. Data across the network connection is only 32 characters x 50 or >> 1600 bytes/sec. Less than a 500th of the 100 Mb/s network bandwidth >> (being generous). >> > > >> All of the above though, implies that you are happy to write your own >> code. Buying building blocks off the shelf can be very attractive. For >> multiple instruments you could buy several PSN A/D boards. To overcome >> the potential problem of connecting up multiple RS232 cables, you could >> use a network terminal server (such as >> http://www.perle.com/products/IOLAN-STS-Terminal-Server.shtml?rack ). >> These aggregate up to 4/8/16/24 rs232 connections on to one network >> connection. They usually come with software for the pc which creates >> multiple virtual COM ports, so your A/D boards would look like they are >> plugged into an array of COM ports on the PC. >> > > >> Isn't technology wonderful! >> > > >> Cheers >> > > >> Ian >> > > >> ChrisAtUpw@....... wrote: >> >>> In a message dated 04/01/2008, gpayton880@....... writes: >>> > > >>> But rather than have 1 sensor on a single socket it is more >>> sensible to >>> have many sensors on a single socket using a data protocol. This >>> is how >>> I have designed my system. It sends out a continuous stream (50 >>> samples >>> per second) of "(Lehman reading) (geophone reading) (time >>> stamp)". My >>> graphing program makes a connection to the "data server" and plots >>> the >>> values from the 2 sensors as they arrive. See >>> http://www.iasmith.com . >>> > > >>> Hi Ian, >>> >>> The limitation tends to be the total data throughput >>> speed reqired. 50 SPS is quite fast. The ADC sample rate can also >>> impose limitations. This starts to become serious when you have, say >>> several three off three channel sensors on the same ADC. >>> >>> Regards, >>> >>> Chris Chapman >>> > > > > > -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: Hekla volcano geophone planned From: Angel sismos@.............. Date: Sat, 5 Jan 2008 16:13:08 +0000 Hello Ian, Just to get an idea, how many PSN-ADC-SERIAL Version II with GPS timing and full time internet connection are there out there. I have one. Angel Saturday, January 5, 2008, 3:57:40 PM, you wrote: > Hi, > yes, you're right, all free. I was really addressing the earlier > (possibly hypothetical) question of how to connect many sensors to 1 > network connection. The engineer in me probably made my response a bit > enthusiastic and suitable for connecting dozens of sensors. > Back to (free) reality! > Cheers > Ian > http://www.iasmith.com/ > http://www.festivalpreviews.com > Angel wrote: >> Hello Ian, >> I have not read each messages of this thread careful but I will. All of the software needed to link a large distributed seismic system is free and freely available. >> Anyone who has one of Larry's 16 bit 8 channel boards with GPS (wwv) timing and a full time internet connection can share data and PSN can a global or regional system auto locating system. >> Angel >> Saturday, January 5, 2008, 9:35:41 AM, you wrote: >> >>> Hi, >>> >> >>> actually, I don't think I'm near any limits. The A/D I use can handle >>> 20K samples/sec. I only have 2 instruments (though I sample each on 3 >>> A/D channels to get the resolution up to 22 bits), so that's only 6 x >>> 50, or 300 samples/sec. So I could connect up all of the A/D's 16 input >>> channels and still not stress it. >>> >> >>> The data server does burn up 80% of the PC's CPU but it's only an old >>> 800 MHz machine and wouldn't cost much to replace with one twice the >>> speed. Data across the network connection is only 32 characters x 50 or >>> 1600 bytes/sec. Less than a 500th of the 100 Mb/s network bandwidth >>> (being generous). >>> >> >>> All of the above though, implies that you are happy to write your own >>> code. Buying building blocks off the shelf can be very attractive. For >>> multiple instruments you could buy several PSN A/D boards. To overcome >>> the potential problem of connecting up multiple RS232 cables, you could >>> use a network terminal server (such as >>> http://www.perle.com/products/IOLAN-STS-Terminal-Server.shtml?rack ). >>> These aggregate up to 4/8/16/24 rs232 connections on to one network >>> connection. They usually come with software for the pc which creates >>> multiple virtual COM ports, so your A/D boards would look like they are >>> plugged into an array of COM ports on the PC. >>> >> >>> Isn't technology wonderful! >>> >> >>> Cheers >>> >> >>> Ian >>> >> >>> ChrisAtUpw@....... wrote: >>> >>>> In a message dated 04/01/2008, gpayton880@....... writes: >>>> >> >>>> But rather than have 1 sensor on a single socket it is more >>>> sensible to >>>> have many sensors on a single socket using a data protocol. This >>>> is how >>>> I have designed my system. It sends out a continuous stream (50 >>>> samples >>>> per second) of "(Lehman reading) (geophone reading) (time >>>> stamp)". My >>>> graphing program makes a connection to the "data server" and plots >>>> the >>>> values from the 2 sensors as they arrive. See >>>> http://www.iasmith.com . >>>> >> >>>> Hi Ian, >>>> >>>> The limitation tends to be the total data throughput >>>> speed reqired. 50 SPS is quite fast. The ADC sample rate can also >>>> impose limitations. This starts to become serious when you have, say >>>> several three off three channel sensors on the same ADC. >>>> >>>> Regards, >>>> >>>> Chris Chapman >>>> >> -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Sat, 05 Jan 2008 16:24:56 +0000 Hi, I don't know. I don't have one. Presumably an approximation can be got from http://www.sydneystormcity.com/people.htm Cheers Ian Angel wrote: > Hello Ian, > > Just to get an idea, how many PSN-ADC-SERIAL Version II with GPS timing and full time internet connection are there out there. > > I have one. > > Angel > > Saturday, January 5, 2008, 3:57:40 PM, you wrote: > > >> Hi, >> > > >> yes, you're right, all free. I was really addressing the earlier >> (possibly hypothetical) question of how to connect many sensors to 1 >> network connection. The engineer in me probably made my response a bit >> enthusiastic and suitable for connecting dozens of sensors. >> > > >> Back to (free) reality! >> > > >> Cheers >> > > >> Ian >> http://www.iasmith.com/ >> http://www.festivalpreviews.com >> > > >> Angel wrote: >> >>> Hello Ian, >>> > > >>> I have not read each messages of this thread careful but I will. All of the software needed to link a large distributed seismic system is free and freely available. >>> > > >>> Anyone who has one of Larry's 16 bit 8 channel boards with GPS (wwv) timing and a full time internet connection can share data and PSN can a global or regional system auto locating system. >>> > > >>> Angel >>> > > > > >>> Saturday, January 5, 2008, 9:35:41 AM, you wrote: >>> > > >>> >>> >>>> Hi, >>>> >>>> > > >>> >>> >>>> actually, I don't think I'm near any limits. The A/D I use can handle >>>> 20K samples/sec. I only have 2 instruments (though I sample each on 3 >>>> A/D channels to get the resolution up to 22 bits), so that's only 6 x >>>> 50, or 300 samples/sec. So I could connect up all of the A/D's 16 input >>>> channels and still not stress it. >>>> >>>> > > >>> >>> >>>> The data server does burn up 80% of the PC's CPU but it's only an old >>>> 800 MHz machine and wouldn't cost much to replace with one twice the >>>> speed. Data across the network connection is only 32 characters x 50 or >>>> 1600 bytes/sec. Less than a 500th of the 100 Mb/s network bandwidth >>>> (being generous). >>>> >>>> > > >>> >>> >>>> All of the above though, implies that you are happy to write your own >>>> code. Buying building blocks off the shelf can be very attractive. For >>>> multiple instruments you could buy several PSN A/D boards. To overcome >>>> the potential problem of connecting up multiple RS232 cables, you could >>>> use a network terminal server (such as >>>> http://www.perle.com/products/IOLAN-STS-Terminal-Server.shtml?rack ). >>>> These aggregate up to 4/8/16/24 rs232 connections on to one network >>>> connection. They usually come with software for the pc which creates >>>> multiple virtual COM ports, so your A/D boards would look like they are >>>> plugged into an array of COM ports on the PC. >>>> >>>> > > >>> >>> >>>> Isn't technology wonderful! >>>> >>>> > > >>> >>> >>>> Cheers >>>> >>>> > > >>> >>> >>>> Ian >>>> >>>> > > >>> >>> >>>> ChrisAtUpw@....... wrote: >>>> >>>> >>>>> In a message dated 04/01/2008, gpayton880@....... writes: >>>>> >>>>> > > >>> >>> >>>>> But rather than have 1 sensor on a single socket it is more >>>>> sensible to >>>>> have many sensors on a single socket using a data protocol. This >>>>> is how >>>>> I have designed my system. It sends out a continuous stream (50 >>>>> samples >>>>> per second) of "(Lehman reading) (geophone reading) (time >>>>> stamp)". My >>>>> graphing program makes a connection to the "data server" and plots >>>>> the >>>>> values from the 2 sensors as they arrive. See >>>>> http://www.iasmith.com . >>>>> >>>>> > > >>> >>> >>>>> Hi Ian, >>>>> >>>>> The limitation tends to be the total data throughput >>>>> speed reqired. 50 SPS is quite fast. The ADC sample rate can also >>>>> impose limitations. This starts to become serious when you have, say >>>>> several three off three channel sensors on the same ADC. >>>>> >>>>> Regards, >>>>> >>>>> Chris Chapman >>>>> >>>>> > > > > > >>> >>> > > > > > -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: "Thomas Dick" dickthomas01@............. Date: Sat, 5 Jan 2008 10:39:25 -0600 Are you familiar with UltraVNC Viewer. It allows me to access the earthquake recording computer anywhere I can find wifi? Some business computer articles give it a high security rating. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Sat, 05 Jan 2008 16:54:20 +0000 Hi, yes, I use it to look directly at my seismometer pc which is in the workshop. It works very well. Ian Thomas Dick wrote: > Are you familiar with UltraVNC Viewer. It allows me to access the > earthquake recording computer anywhere I can find wifi? Some business > computer articles give it a high security rating. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ChrisAtUpw@....... Date: Sat, 5 Jan 2008 14:41:40 EST In a message dated 05/01/2008, ian@........... writes: Hi, actually, I don't think I'm near any limits. The A/D I use can handle 20K samples/sec. Hi Ian, What ADC are you using? 20 K SPS is 50 micro sec / sample. My ADC takes 20 muS/S. How does it's accuracy depend on it's sample rate? Does it have an onboard processor chip to take and average multiple samples? What data rate does the ADC board to computer link support? I only have 2 instruments (though I sample each on 3 A/D channels to get the resolution up to 22 bits), so that's only 6 x 50, or 300 samples/sec. You need to average four samples to get 1 additional bit of accuracy, 16 samples to get two bits extra, etc. So I could connect up all of the A/D's 16 input channels and still not stress it. This is likely to be ~40 bytes total with the overheads at 50 SPS, say 16 K bits/ sec. If you are using a 24 bit ADC, it is likely double this. Then it largely depends on whether you are sending datapackets, or individual bytes. If you are sending asynchronous bytes, you have to wait for the signal to be transmitted, the receiving server to respond and the ACK to be received. Transmission delays can be significant. I am 12 km from the phone terminal, so the delay would be well over 80 micro sec per byte. Coupled to a a 56 K modem, I certainly could not transmit this much data. The data server does burn up 80% of the PC's CPU but it's only an old 800 MHz machine and wouldn't cost much to replace with one twice the speed. Data across the network connection is only 32 characters x 50 or 1600 bytes/sec. Less than a 500th of the 100 Mb/s network bandwidth (being generous). So, do you know what minimum speed you can actually get for asynchronous transmissions? The broadband data rates quoted by the service providers are usually maximums in the best possible conditions, not the average and certinly not guaranteed. They may not allow for transmission delays. Reality may be only a small fraction of the specs advertised! A recent BB survey in the UK suggested a far lower preformance, nearer to that of the 56 K modems. Regards, Chris Chapman
In a message dated 05/01/2008, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Hi,
actually, I don't think I'm near any limits.  The A/D= I use=20 can handle 20K samples/sec. 
Hi Ian,
 
    What ADC are you using? 20 K SPS is 50 micro se= c /=20 sample. My ADC takes 20 muS/S.
    How does it's accuracy depend on it's sample=20 rate?
    Does it have an onboard processor chip to take=20= and=20 average multiple samples?
    What data rate does the ADC board to computer l= ink=20 support?
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I only=20 have 2 instruments (though I sample each on 3 A/D channels to get the=20 resolution up to 22 bits), so that's only 6 x 50, or 300 samples/sec. = ;=20
    You need to average four samples to get 1=20 additional bit of accuracy, 16 samples to get two bits extra, etc.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>So I=20 could connect up all of the A/D's 16 input channels and still not stress=20 it.
    This is likely to be ~40 bytes total with the=20 overheads at 50 SPS, say 16 K bits/ sec. If you are using a 24 bit ADC, it i= s=20 likely double this. Then it largely depends on whether you are sending=20 datapackets, or individual bytes.
    If you are sending asynchronous bytes, you have= to=20 wait for the signal to be transmitted, the receiving server to respond and t= he=20 ACK to be received. Transmission delays can be significant. 
    I am 12 km from the phone terminal, so the dela= y=20 would be well over 80 micro sec per byte. Coupled to a a 56 K modem, I certa= inly=20 could not transmit this much data.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The data=20 server does burn up 80% of the PC's CPU but it's only an old 800 MHz machi= ne=20 and wouldn't cost much to replace with one twice the speed.  Data acr= oss=20 the network connection is only 32 characters x 50 or 1600 bytes/sec. = =20 Less than a 500th of the 100 Mb/s network bandwidth
(being=20 generous).
    So, do you know what minimum speed you=20 can actually get for asynchronous transmissions? The broadband data rat= es=20 quoted by the service providers are usually maximums in the best possible=20 conditions, not the average and certinly not guaranteed. They may not a= llow=20 for transmission delays. Reality may be only a small fraction of the specs=20 advertised! A recent BB survey in the UK suggested a far lower preformance,=20 nearer to that of the 56 K modems.
 
    Regards,
 
    Chris Chapman
Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Sat, 05 Jan 2008 22:08:22 +0000 Hi, I was waiting nervously for your reply and an array of astute questions; here they are! :-) I'll try to answer as best as possible. My A/D is a National Instruments AT-MIO-16XE-50 which plugs directly into the motherboard, so no communication issues. The data sheet is at http://www.ni.com/pdf/products/us/2mhw254-255e.pdf and the manual is at http://www.ni.com/pdf/manuals/370507a.pdf From the manual, sampling rate is only a consideration when switching gain between channels (which I am, see later), otherwise full tilt is fine. The board does have a micro with which it can perform various tricks. Higher bit systems give both higher resolution and higher dynamic range. I think the main concern for seismometry, amongst cash limited amateurs, is the dynamic range to try to avoid saturation when a strong signal comes in. So, with my 16 bit A/D, I feed the signal into 3 separate channels and sample each of them at 3 different gains, +/-0.1V, +/-1.0V and +/-10V. The software then chooses the reading with the greatest gain which hasn't saturated. So that gives it an "effective" bit rating of 20V/3.05e-6V or just over 22 bits for dynamic range but still 16 bits for resolution. As said above, changing gain between channels does have settling issues. To eliminate this effect, I should increase the intra-channel sampling time. However, this would increase the skew between the 3 samples, which would introduce another source of noise. I should really measure/calculate these competing effects and find the optimum point. For this application, though, I am content. I used to use a 12 bit system, so my present system is much better even with these features. I'm squirting the data across my own intranet to the graphing computer, so am getting most of the available 100 Mb/s bandwidth with minimal latency. For those using the internet, there shouldn't be a problem provided the data are timestamped at source. It then doesn't matter how long the data takes to arrive or whether the times between samples varies, the data can be properly reassembled using the individual timestamps. Things though are more limited with 56K modems. I'd be interested to hear how there is a 12 Km "gap" in your system. Cheers Ian http://www.iasmith.com/ http://www.festivalpreviews.com/ ChrisAtUpw@....... wrote: > In a message dated 05/01/2008, ian@........... writes: > > Hi, > actually, I don't think I'm near any limits. The A/D I use can > handle 20K samples/sec. > > Hi Ian, > > What ADC are you using? 20 K SPS is 50 micro sec / sample. My ADC > takes 20 muS/S. > How does it's accuracy depend on it's sample rate? > Does it have an onboard processor chip to take and average > multiple samples? > What data rate does the ADC board to computer link support? > > I only have 2 instruments (though I sample each on 3 A/D channels > to get the resolution up to 22 bits), so that's only 6 x 50, or > 300 samples/sec. > > You need to average four samples to get 1 additional bit of > accuracy, 16 samples to get two bits extra, etc. > > So I could connect up all of the A/D's 16 input channels and still > not stress it. > > This is likely to be ~40 bytes total with the overheads at 50 SPS, > say 16 K bits/ sec. If you are using a 24 bit ADC, it is likely double > this. Then it largely depends on whether you are sending datapackets, > or individual bytes. > If you are sending asynchronous bytes, you have to wait for the > signal to be transmitted, the receiving server to respond and the ACK > to be received. Transmission delays can be significant. > I am 12 km from the phone terminal, so the delay would be well > over 80 micro sec per byte. Coupled to a a 56 K modem, I certainly > could not transmit this much data. > > The data server does burn up 80% of the PC's CPU but it's only an > old 800 MHz machine and wouldn't cost much to replace with one > twice the speed. Data across the network connection is only 32 > characters x 50 or 1600 bytes/sec. Less than a 500th of the 100 > Mb/s network bandwidth > (being generous). > > So, do you know what minimum speed you can actually get for > asynchronous transmissions? The broadband data rates quoted by the > service providers are usually maximums in the best possible > conditions, not the average and certinly not guaranteed. They may not > allow for transmission delays. Reality may be only a small fraction of > the specs advertised! A recent BB survey in the UK suggested a far > lower preformance, nearer to that of the 56 K modems. > > Regards, > > Chris Chapman -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Wrong clock From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sun, 06 Jan 2008 01:04:33 +0000 Hi all I did noticet that station that has the id jcc1 has a wrong clock in place. But according to the event file list, this is the date that it is using. 12/05/08 11:01 UTC 12/05/08 03:01 Local Time This is a massive time error. I hope that the owner can fix this before the next big quake near west coast of Canada. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake near cost of Canada From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sun, 06 Jan 2008 01:15:31 +0000 Hi all I do belive that West coast of Canada is at risk of getting a new big earthquake, possible around mag 6.5, but there is at least 12% chance of mag 7.0 or bigger earthquake in the area close to the two mag 6.5 earthquakes that did happen yesterday. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ChrisAtUpw@....... Date: Sat, 5 Jan 2008 21:20:06 EST In a message dated 05/01/2008, ian@........... writes: I'm squirting the data across my own intranet to the graphing computer, so am getting most of the available 100 Mb/s bandwidth with minimal latency. Hi Ian, Communication links usually have fixed baud rates. What are you using? For those using the internet, there shouldn't be a problem provided the data are timestamped at source. It then doesn't matter how long the data takes to arrive or whether the times between samples varies, the data can be properly reassembled using the individual rimestamps. ? If you are sending asynchronous data, you send a byte maybe ~11 cycles long overall, which has start and stop bits. You usually send the signal, the receiver processes it and sends an ACK signal back. Then you send the next byte. If you try simply sending at a fixed baud rate, you inevitably get dropouts. You have to complete the process with the time stamp data to be able to reassemble it. Your bus also has a fixed interrupt repeat rate, when the CPU checks what tasks are currently waiting. Only a few interrupts in a multitasking system redirect the CPU instantly. Things though are more limited with 56K modems. I'd be interested to hear how there is a 12 Km "gap" in your system. Dead simple. This is the distance between my modem and the digital receiver in the phone exchange. 56 K modems rarely work at this rate. I limit mine to 38 K, sometimes less. This avoids my computer having to request a lot of data repeats, which can waste a lot of time. I note that the ADC board uses the computer supply lines. These can be quite noisy. What noise do you generally see with the input line to earth? How many times has your system had to use a restricted amplification range channel? These are only common if you get local quakes. I have yet to receive an out of range quake signal with my 16 bit +/-1/2 lsb system. Regards, Chris Chapman
In a message dated 05/01/2008, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I'm=20 squirting the data across my own intranet to the graphing computer, so am=20 getting most of the available 100 Mb/s bandwidth with minimal=20 latency.
Hi Ian,
 
    Communication links usually have fixed baud rat= es.=20 What are you using?
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>For=20 those using the internet, there shouldn't be a problem provided the data a= re=20 timestamped at source.  It then doesn't matter how long the data take= s to=20 arrive or whether the times between samples varies, the data can be proper= ly=20 reassembled using the individual rimestamps.
    ? If you are sending asynchronous data, you sen= d a=20 byte maybe ~11 cycles long overall, which has start and stop bits. You usual= ly=20 send the signal, the receiver processes it and sends an ACK signal back. The= n=20 you send the next byte. If you try simply sending at a fixed baud=20 rate, you inevitably get dropouts. You have to complete the process wit= h=20 the time stamp data to be able to reassemble it. Your bus also has a fixed=20 interrupt repeat rate, when the CPU checks what tasks are currently=20 waiting. Only a few interrupts in a multitasking system redirect the CP= U=20 instantly.
 
    Things though are more limited with 56K=20 modems.  I'd be interested to hear how there is a 12 Km "gap" in your=20 system.
 
    Dead simple. This is the distance between my mo= dem=20 and the digital receiver in the phone exchange.
 
    56 K modems rarely work at this rate. I lim= it=20 mine to 38 K, sometimes less. This avoids my computer having to request a lo= t of=20 data repeats, which can waste a lot of time.
 
    I note that the ADC board uses the computer sup= ply=20 lines. These can be quite noisy. What noise do you generally see with the in= put=20 line to earth?
 
    How many times has your system had to use a=20 restricted amplification range channel? These are only common if you ge= t=20 local quakes. I have yet to receive an out of range quake signal with my 16=20= bit=20 +/-1/2 lsb system.
 
    Regards,
 
    Chris Chapman
Subject: Re: Hekla volcano geophone planned From: ian ian@........... Date: Sun, 06 Jan 2008 13:03:04 +0000 Hi, I've just had a refresher look at the software. The A/D board has it's own crystal controlled timing to trigger the sampling and to control the time between channel samples. There is also a 4000 sample FIFO buffer to store the readings, so the timing of the samples is absolutely rock solid and unaffected by activities on the pc. Where I deserve a wrist smack is the timestamps. These are applied as each sample group (the 3 samples for each of the 2 instruments) are read from the FIFO buffer and therefore are affected by activities on the pc. I'll add this to my todo list to use the A/D's internal timing for timestamps. For communication it's just standard 100 mbit tcp/ip. Totally transparent to the user and given that the data is all timestamped (sort of!) not something to worry about. I'll need to measure the noise to answer the noise question. Looking back I can see that there are a few traces (not many) which flipped between channel gains +/-0.1V and +/-1.0V. So the feature is giving me more gain to look into the weaker signals without being clobbered with saturation on the stronger traces - both the high and low pass filters apply a 20db gain to compensate for the attenuation of the filters. I asked about your 12 Km gap as I was wondering if there was a way to plug it with equipment running at broadband rates. I'm in one of the BT(our telco) "black spots", condemned to never have broadband and I eventually had to put together our own community wireless broadband (http://www.gmccbroadband.org/ ). This partly involves filling "gaps" across the countryside. Our biggest gap is only 5 Km so the stuff we use might not help. We use Tranzeo 5Ghz point-to-point access points, these require line of sight between the two locations. They might cover 12 Km but I'm not sure. Equipment is about £450 and you'll need to pay someone to install it on the roof. The other method is to rent a "private circuit" or EPS line from BT - a private wire between two premises sharing the same exchange - over which you can connect a pair of sdsl modems. These may not work over the distance, again I'm not sure. Costs about £45/month. Maybe that's what you are already doing. Cheers Ian http://www.iasmith.com http://www.festivalpreviews.com ChrisAtUpw@....... wrote: > In a message dated 05/01/2008, ian@........... writes: > > I'm squirting the data across my own intranet to the graphing > computer, so am getting most of the available 100 Mb/s bandwidth > with minimal latency. > > Hi Ian, > > Communication links usually have fixed baud rates. What are you using? > > For those using the internet, there shouldn't be a problem > provided the data are timestamped at source. It then doesn't > matter how long the data takes to arrive or whether the times > between samples varies, the data can be properly reassembled using > the individual rimestamps. > > ? If you are sending asynchronous data, you send a byte maybe ~11 > cycles long overall, which has start and stop bits. You usually send > the signal, the receiver processes it and sends an ACK signal back. > Then you send the next byte. If you try simply sending at a fixed baud > rate, you inevitably get dropouts. You have to complete the process > with the time stamp data to be able to reassemble it. Your bus also > has a fixed interrupt repeat rate, when the CPU checks what tasks are > currently waiting. Only a few interrupts in a multitasking system > redirect the CPU instantly. > > Things though are more limited with 56K modems. I'd be interested > to hear how there is a 12 Km "gap" in your system. > > Dead simple. This is the distance between my modem and the digital > receiver in the phone exchange. > > 56 K modems rarely work at this rate. I limit mine to 38 K, > sometimes less. This avoids my computer having to request a lot of > data repeats, which can waste a lot of time. > > I note that the ADC board uses the computer supply lines. These > can be quite noisy. What noise do you generally see with the input > line to earth? > > How many times has your system had to use a restricted > amplification range channel? These are only common if you get local > quakes. I have yet to receive an out of range quake signal with my 16 > bit +/-1/2 lsb system. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake near cost of Canada From: "Geoff" gmvoeth@........... Date: Sun, 6 Jan 2008 16:34:47 -0700 Isnt that area a subduction zone ? You get the biggest EQs at subduction Zones. You might get one like thay had off sumatra one day. ----- Original Message ----- From: "Jón Frímann" To: Sent: Saturday, January 05, 2008 6:15 PM Subject: Re: Large earthquake near cost of Canada Hi all I do belive that West coast of Canada is at risk of getting a new big earthquake, possible around mag 6.5, but there is at least 12% chance of mag 7.0 or bigger earthquake in the area close to the two mag 6.5 earthquakes that did happen yesterday. Regards. -- Jón Frímann http://www.jonfr.com http://earthquakes.jonfr.com http://www.net303.net http://www.mobile-coverage.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake near cost of Canada From: Bob Hancock carpediem1@......... Date: Sun, 06 Jan 2008 16:54:21 -0700 Geoff - The Queen Charlotte fault is a transform fault; however, there are sections both north and south that have different names and are either transform or subduction. The mechanics of these two major recent events indicate a strike slip movement. Bob Hancock On 1/6/08 4:34 PM, "Geoff" wrote: > Isnt that area a subduction zone ? > You get the biggest EQs at subduction Zones. >=20 > You might get one like thay had off sumatra one day. >=20 > ----- Original Message ----- > From: "J=F3n Fr=EDmann" > To: > Sent: Saturday, January 05, 2008 6:15 PM > Subject: Re: Large earthquake near cost of Canada >=20 >=20 > Hi all >=20 > I do belive that West coast of Canada is at risk of getting a new big > earthquake, possible around mag 6.5, but there is at least 12% chance of > mag 7.0 or bigger earthquake in the area close to the two mag 6.5 > earthquakes that did happen yesterday. >=20 > Regards. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Hekla volcano geophone planned From: ChrisAtUpw@....... Date: Sun, 6 Jan 2008 19:15:48 EST In a message dated 06/01/2008, ian@........... writes: Looking back I can see that there are a few traces (not many) which=20 flipped between channel gains +/-0.1V and +/-1.0V. So the feature is=20 giving me more gain to look into the weaker signals without being=20 clobbered with saturation on the stronger traces - both the high and low=20 pass filters apply a 20db gain to compensate for the attenuation of the =20 filters. Hi Ian, =20 I would expect that all your out of range signals will be due to the=20 surface waves?=20 I asked about your 12 Km gap as I was wondering if there was a way to=20 plug it with equipment running at broadband rates. I'm in one of the=20 BT(our telco) "black spots", condemned to never have broadband and I =20 eventually had to put together our own community wireless broadband =20 (http://www.gmccbroadband.org/ ). This partly involves filling "gaps"=20 across the countryside. Our biggest gap is only 5 Km so the stuff we=20 use might not help.=20 The delay that I quoted was due to the speed of light over the distance= ,=20 but the phase velocity in the wires will be lower. I have not measured it.=20 I only require four or five channels, not eight. =20 One standard fix is to send the data as packets, so greatly reducing th= e=20 number of delays..=20 We use Tranzeo 5Ghz point-to-point access points, these require line of=20 sight between the two locations. They might cover 12 Km but I'm not sure.=20= =20 Equipment is about =A3450 and you'll need to pay someone to install it on th= e roof. This is quite expensive. Even if I did install an aerial on my roof,=20 there is still a hill in the way. Nor does it solve the problem of the two= way=20 signal delays. =20 // At the RF level, the system also reduces latency and improves=20 throughput by allowing the user to adjust the RF ACK time, changing the amo= unt of=20 time the system will wait for an RF ACK to be returned. Radio waves take a=20 finite amount of time to reach a destination, namely the speed of light. Ev= ery=20 packet sent via an RF link needs to be acknowledged, in order to ensure that the packet was=20 received intact. // The other method is to rent a "private circuit" or EPS line from BT - a=20 private wire between two premises sharing the same exchange - over which y= ou can=20 connect a pair of sdsl modems. These may not work over the distance, agai= n=20 I'm not sure. Costs about =A345/month. Maybe that's=20 what you are already doing. I have not tried to explore this recently. When I last enquired, BT were no= t=20 prepared to lay an additional 12 km of phone line. And they didn't have a=20 spare line on their local cable. There is a relationship between the distan= ce=20 to the phone exchange and the maximum speed. There was also a maximum=20 distance. From memory this was about 5 km when I enquired. =20 Regards, =20 Chris Chapman =20
In a message dated 06/01/2008, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Looking=20 back I can see that there are a few traces (not many) which
flipped=20 between channel gains +/-0.1V and +/-1.0V.  So the feature is
giv= ing=20 me more gain to look into the weaker signals without being
clobbered w= ith=20 saturation on the stronger traces - both the high and low
pass filters= =20 apply a 20db gain to compensate for the attenuation of the=20
filters.
Hi Ian,
 
    I would expect that all your out of range signa= ls=20 will be due to the surface waves? 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I asked=20 about your 12 Km gap as I was wondering if there was a way to
plug it=20= with=20 equipment running at broadband rates.  I'm in one of the
BT(our=20 telco)  "black spots", condemned to never have broadband and I=20
eventually had to put together our own community wireless broadband=20
(http://www.gmccbroadband.org/ ).  This partly involves filling=20 "gaps"
across the countryside.  Our biggest gap is only 5 Km so t= he=20 stuff we
use might not help.
    The delay that I quoted was due to the spe= ed=20 of light over the distance, but the phase velocity in the wires will be lowe= r. I=20 have not measured it.
    I only require four or five channels, not=20 eight.
 
    One standard fix is to send the data=20 as packets, so greatly reducing the number of delays..
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>We use=20 Tranzeo 5Ghz point-to-point access points, these require line of sight bet= ween=20 the two locations.  They might cover 12 Km but I'm not sure. =20 Equipment is about =A3450 and you'll need to pay someone to install it on=20= the=20 roof.
    This is quite expensive. Even if I did install=20= an=20 aerial on my roof, there is still a hill in the way. Nor does it  solve= the=20 problem of the two way signal delays.
 
//    At the RF level, the system also reduces late= ncy=20 and improves throughput by allowing the user to adjust the RF ACK time, chan= ging=20 the amount of time the system will wait for an RF ACK to be returned. Radio=20 waves take a finite amount of time to reach a destination, namely the speed=20= of=20 light. Every packet sent via an
RF link needs to be acknowledged, in orde= r to=20 ensure that the packet was received intact.
//
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 other method is to rent a "private circuit" or EPS line from BT - a privat= e=20 wire between two premises sharing the same exchange -  over which you= can=20 connect a pair of sdsl modems.  These may not work over the distance,= =20 again I'm not sure.  Costs about =A345/month.  Maybe that's
= what=20 you are already doing.
    I have not tried to explore this recently. When= I=20 last enquired, BT were not prepa