PSN-L Email List Message

Subject: RE: Time/Filtering
From: "Steve Hammond" shammon1@.............
Date: Mon, 16 May 2005 23:41:05 -0700

Hi, I was thinking about simple ways to measure this and was able to use one
of the unused channels on Larry's A/D board by splitting the unfiltered data
from one of my sensors into it before it was filtered. After capturing some
sample data,  I picked a nice large spike from one of the datasets and was
able to see an approximate 60ms delay when comparing the filtered and
unfiltered datasets. I'm using the Pete Rowe filter design Amp/filter found
at and this is
consistent with what I expected to see.
Regards, Steve Hammond  PSN San Jose
Aptos, CA

-----Original Message-----
From: psn-l-request@..............
[mailto:psn-l-request@................. Behalf Of Larry Cochrane
Sent: Tuesday, May 10, 2005 11:44 PM
To: psn-l@..............
Subject: Re: Time/Filtering

Hi Bryan,

If your A/D board was locked to GPS time your timing accuracy is closer to
+-5ms. The
filter delay is more or less constant and can be factor out by placing the
delay time in WinSDR. In the Channel Settings dialog box you will see a
Delay" edit box. For now use 50 ms. When I get some time I will measure the
delay of
one of my Amp/Filter board channels and place this information on my Web

Besides accurate timing you should also have an accurate location of you
station. I
noticed that the PSN files you placed on your web site did not have the
Latitude and
Longitude data filled out or the file only had the location too two decimal
Since you have a GPS receiver you can use it to locate you station's
location to a
few meters.  If you run the current beta version of WinSDR you can use it to
the position information from the GPS receiver connected to the A/D board.
See for more information. If
you let
WinSDR average the data for a day or two you will have a very accurate
latitude and
longitude number.

Larry Cochrane

Bryan wrote:
> Ok so what should I tell CERI   I am getting a lot of different numbers
from the replies? Would I be ok
 >to say with filtering I should be within +/- 50ms also will this be good
enough to
accurately locate
 >a local events with 3 stations less than 50 miles apart. This will explain
why I
ask is a clip
 >from a letter from Mitch.


Public Seismic Network Mailing List (PSN-L)


Public Seismic Network Mailing List (PSN-L)

[ Top ] [ Back ] [ Home Page ]