PSN-L Email List Message
Subject: Re: computer time sync
From: "Meredith Lamb" meredithlamb@.............
Date: Sun, 18 Apr 2004 20:35:10 -0600
Forwarded reply from chrisatupw@........
> [Original Message]
> To: tdick
> Date: 4/14/2004 8:43:47 PM
> Subject: Re: computer time sync
> I also have notice over the last year that that it is harder to get
> good time from timeservers. Every little Dlink dsl router (and most other
> brands) have time clients and the timeservers in many cases can't
> respond in a timely way because of the huge number of request.
> I now have my main computer with a GPS and I send the time with Tardis
> to all the computers on my network who listen with K9 it is a bit
> better. I am slowly moving to GPS on all systems.
> Consider GPS or WWV
> You also might consider using Righttime software, I would hold your
> time much better than 20 seconds.
> I think all station should have good time.
> Thursday, April 15, 2004, 1:52:28 AM, you wrote:
> t> I am using Dimension 4 to sync the time on the computer that runs only
> t> WinSDR. My time seems to vary. In an event yesterday, St. Louis
> t> my computer were 20 seconds off for the same event. Any suggestions?
Look up the coverage of WWVB on 60 KHz. You should be able to receive
much / all of the US. See
http://www.boulder.nist.gov/timefreq/stations/wwvb.htm It is
certainly available in St. Louis! Oregon Scientific sells 60 KHz radio
clocks, which are
Quartz crystal but which update hourly. The plain radio alarm clocks are
expensive (US$18?) and are really quite sophisticated devices. They have a
'aerial' display to indicate when they have updated and display the time to
You should get better than 20 milli sec accuracy, probably less than 5 ms
can extract a 1 sec signal from an OS clock. 60 KHz is more reliable, if
you can use it,
than WWV on 2.5, 5, 10 and 15 MHz.
WWV can be used with a pll decoder and a digital receiver as described on
You get selective fading on WWV over the various frequencies, which depends
on day/ night
boundaries and on ionospheric reflection.
If you want Radio modules, try contacting the manufacturer on
They also supply the WWVB time decoder modules to read into a computer
complete timer subsystems. They don't list a US stockist, but I suspect
that there is one or
more. The UK receivers are also designed to operate on 60 KHz. My
DCF77 and MSF over europe indicate that the receivers have AMPLE
sensitivitiy with their
ferrite aerials to over 2000km. Fringe reception can be improved with a
long wire Beveridge
aerial and a coupling coil. The factors which comonly limit reception are
local RF interference,
steel mesh fencing and thunderstorms. At ~2000 km range in Seville in
southern Spain, the
local RF interference prevented good daytime reception, but 20 miles
outside town there was
no problem. There was no problem in Seville town centre using the stronger
signal. There is more info and discussion on
However, I agree that GPS will be more accurate and reliable, always
assuming that you
can / want to / afford it.
Regards, Chris Chapman
Public Seismic Network Mailing List (PSN-L)
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