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Re: [wsjtgroup] GPS time roving?

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  • Bill VanAlstyne W5WVO
    The secret to keeping your computer clock accurate without updating it automatically is to make sure your computer is not overtaxed. The Windows RTC is a
    Message 1 of 4 , Jan 6, 2011
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      The secret to keeping your computer clock accurate without updating it automatically is to make sure your computer is not overtaxed. The Windows RTC is a software clock, and it will start to lose time when the CPU gets up towards fully loaded. A computer with cycles to spare will keep fairly accurate time over several weeks.
      I have a so-called “atomic” wristwatch, as well. The cheapie ones can lose up to a second a day between nightly WWVB updates, but mine is a $500 Junghans from Germany, and it is incredibly accurate. I can check it against WWV at any time of the day or night, and it is precisely accurate to as close as I can eyeball it. You get what you pay for LOL.
      I have yet to see a laptop plug-in PCM card with a WWVB receiver on it. Seems like an obvious product, but I guess the only people who care about PC time that accurate when off-line are ham radio rovers – kinda a small market. :-)
      And yes, there ARE GPS-based solutions to this problem. I’m seen them discussed here on this board and on others.
      Bill W5WVO
      Sent: Thursday, January 06, 2011 14:31
      Subject: RE: [wsjtgroup] GPS time roving?

      As far as the time sync issue is concerned, all that is necessary is to have a good clock or watch with you.  If your watch keeps time within a few seconds per month (as my cheap Casio does), then just set it to your home computer or WWV/CHU before you leave on your trip.  Then before you start operating set your computer clock to agree with your clock.  (Or listen to WWV from your portable location if you can).  Even if you get to be two or more seconds off, it will not make much difference for MS or ISCAT, etc.  For EME you have to be a little more careful, but 2 seconds will still work.
      Obviously if you have a long operating session it would be smart to double check the computer against your clock now and then to make sure the computer is keeping time - maybe every 15-30 minutes.
      73 & Happy roving.
      Russ K2TXB

      From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Bill VanAlstyne W5WVO
      Sent: Thursday, January 06, 2011 7:41 AM
      To: wsjtgroup@yahoogroups.com; John Watrous
      Subject: Re: [wsjtgroup] GPS time roving?


      Hi John,
      I can’t help with the time sync issue while mobile – I know there are solutions – but you might want to think twice about using JT6M. First of all, JT6M is no longer present in the current version of WSJT (v.9). Almost everybody is now using WSJT9, so JT6M is essentially obsolete. It has been replaced by ISCAT, a similar but much better new mode optimized for weak troposcatter, ionoscatter, and sporadic-E signals. It will also work for meteor scatter on 6 meters when the pings are long enough to accommodate the longer messages, but FSK441 is a much better choice for meteor-scatter work.
      In the summer months, you will have both sporadic-E and meteor scatter available to you at different times and in different directions. You have to look and see what kinds of pings you are getting. Typically, longer-distance stations (in the absence of sporadic-E) will have shorter, weaker pings, and FSK441 is a better choice. I would plan on using FSK441 for meteor scatter and ISCAT for constant signal amplitude propagation modes. When both modes are present at once (fairly common during the summer months), ISCAT is a good choice.
      Bill W5WVO
      Sent: Wednesday, January 05, 2011 21:14
      Subject: [wsjtgroup] GPS time roving?

      What do people use to sync the pc clock when roving?

      I am considering a short rove this summer to EN67 and assume no internet
      time available.

      I am also assuming JT6M mode...

      Thanks, John

      John Watrous, K6PZB
      707 360 5496

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