PSN-L Email List Message

Subject: Re: Timing Accuracy Within WinSDR
From: "Thomas Dick" dickthomas01@.............
Date: Tue, 1 Jul 2008 16:00:33 -0500

Thanks for coming back to me Chris. I didn't know if you could handle 2 plus 
megs, at least, if I were you I'd be in the country. I approached Larry on 
this issue and was left unsatisfied...but I may not have made my statements 
as clear as I should.

       First, it is not uncommon to get timing errors of a second or so. The 
Travel Time calculation uses average ground velocities and you may well not 
be average.

And I know you don't use WinQuake but I asked Larry if that is what the 
locate file function is for...he never answered me. And often, I are talking 
minutes here ...not seconds

       I am not sure how WinSDR actually does the timing, even when 
corrected by GPS. The display program will presumably use the software clock 
on your computer. Have you asked Larry? I did ask him if he thought this 
could be a board issue...he didn't think so, he keyed on the travel time 
tables as not applicable in this situation.

The software clocks fitted to PC computers are often crap. They can loose or 
gain 10s of minutes per day.

I got told that my timing was off by Dr. Hermann over at St. Louis U very 
early in my embarking on this seismology stuff. I had already tired the 
software timing stuff. I had started with syncing all my computers to the 
same time even before I got into seismology. Dr. Hermann's comments sent me 
after the satellite timing board from Larry. Generally what I see on USI and 
my display is pretty close. I have recently asked Dr, Hermann about "events" 
in a certain minute of a certain hour and he replies without commenting 
about my timing any more.

       What errors do you see when you check your software clock against 
NIST time?

I turned on the national time station in Boulder Colo and watched it for a 
couple of minutes. The program claimed to be locked on a satellite. I saw 
the time jump two seconds as it hit the minute mark on one occasion. The 
next minute looked like it changed within a half second of the minute mark.

Chalk this up to ignorance, too, I guess. I asked Nelson why a database of 
amateur seismologists. I questioned the inventory of sensors because it is 
posted on the sensor information in the files as posted. He is out of the 
office but a text message from him seemed to give me the idea he was 
confused, so am I. What is to be gained by this database other than 
a lot of information about location and equipment flying around the 

This timing issue has bothered me for over four years. I suspect that if you 
decrease the X (horizontal --i.e. expand time) there is an increased error. 
That is what I hope someone else has noticed...or can tell me where my 
thinking is wrong.

We had another quake last week; somewhere around a mag 3. I can handle mag 
3's but those fours and fives just wiped me out. You know, those geophones 
pick up those nearby quakes better than the Lehmans and AS-1.  I finally put 
braces on the hot water heater and started looking at the clutter on high 
shelves. I did anchor my bookcases to the walls many years ago.

As you can see in the file, Bob McClure has me getting sac files from the 
nearby seismic centers and converting to Winquake format. Excpet for the 
time issue, I can accept the output of my equipment in comparison to the 
professional stuff. I know I can't compete!

Did you ever read a book by Peter Hernon titled 8.4? Dr. Hermann hadn't. I 
don't read much fiction. This guy did a lot of homework on the area before 
he wrote the book. Many of the places he mentions in the book I am familiar 
with and all the faults.  Sure there are a few minor faults he left out. And 
the premise on how to stop the earthquakes is as old as I am --almost. 


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