[time-nuts] GPS Timing Source -- looking at buying
Hal Murray
hmurray at megapathdsl.net
Fri Jul 9 01:26:53 UTC 2010
> I was just wondering if the following product:
> http://www.triginstruments.co.nz/catalog/product_info.php?products_id=1302&os
> Csid=b80759ac903096c20d806ddeb3d71121
That's a Garming GPS-18 PC, the version that gets power from a cigarette
lighter. (What are they called now that lots of people don't smoke?)
> Would be good as a timing source for GPS -- does it have the necessary
> outputs and information out the serial interface to make a PC into a Stratum
> 0 timing device?
What do you mean by "stratum 0"? I'm assuming you mean for use with ntpd.
The telephone industry has a different meaning.
There are two quirks in this area.
One is that the GPS-18 has been updated to the GPS-18x. It's much more
sensitive.
The other is to be sure to get a version with a PPS. In particular, the USB
version doesn't have it.
Lots of people use the GPS-18-LVC with ntpd. Info here:
http://support.ntp.org/bin/view/Support/ConfiguringGarminRefclocks
You have to provide power. "Some assembly required.", but it's not a big
deal if you know how to drive a soldering iron.
There are a couple of good links at the bottom of that URL above.
> Make a linux box into a master time source... It says I need windows XP and
> things, or is that just to configure and check connectivity..
Lots of people use the GPS-18-LVC without windows.
> EBU Timecode in LTC format (audio timecode)
The NTP source code package includes a utility to make audio time codes.
Look for tg2.c. I don't know what EBU is, but that code might be a good
place to start.
--
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