[lug] Time sync w/GPS or radio

[Jason Vallery]

Hi All,

I'm a bit late to this thread, but I was working on a separate project
using GPS and came across an interesting product.  Garmin makes a
"puck" GPS receiver that just has a serial cable output on it.  It is
a fairly dumb device that when powered up generates a NMEA 0183 data
stream on the serial interface.  For $70 you can't beat the price.

You can see it here:
http://www.amazon.com/gp/product/B000196BW6/ref=pd_cp_e_0?pf_rd_p=250314601&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B0002HS3A0&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0VEA94MZ10NYQYJF3BX5

If you look at the NMEA spec the data stream contains the UTC time.
It seems like it would be pretty trivial to write up a shell script
that monitors the serial interface and sets the clock based on the
incoming data stream.

http://en.wikipedia.org/wiki/NMEA_0183

I just ordered one and I can't wait to play with it.

-J



On Thu, May 8, 2008 at 4:32 PM, George Sexton <gsexton at mhsoftware.com> wrote:
> I've been wanting a time receiver for a long time. In a previous life, I was
> a calibration technician so I've been fascinated with time and frequency
> standards for a long time. What's been killing me has been the price. It's
> tough for me to explain to my wife that I want to buy a $1500 GPS time
> receiver because I think it would be cool. It's neat to see the Beaglesoft
> one is much cheaper.
>
> I looked at the Radio Sync thing from the Beaglesoft folks, and it's nice at
> $220, but it's not directly supported by NTP. Someone would have to write a
> driver for it.
>
> I saw their GPS receiver is a Garmin GPS-16. For kicks, I went to Garmin's
> site and found the unit for $105.
>
> https://buy.garmin.com/shop/shop.do?cID=158&pID=13194
>
> It looks like you would need to follow these instructions to create an
> RS-232 interface and power supply. There are also instructions on getting
> the PPS stuff working, which is essential for higher accuracy:
>
> http://time.qnan.org/
>
> I'm sure that even if you purchased the kit from Beaglesoft, you would have
> to do the kernel PPS steps on the URL.
>
> This would be a really cool project. I'm halfway handy with a soldering iron
> and I'm sure it wouldn't take much more than an hour to create the PCB.
>
> Lori Reed wrote:
>>
>> IME, gps devices, at least hand held and pcmcia devices, have, at best,
>> problematical indoor reception. A bit of quick googling found this:
>>
>> http://www.atomictimeclock.com/radsynhome.htm
>>
>> I'm sure there are others.
>>
>> Just curious, what is the url for the UK vendor you reference?
>>
>> Lori
>>
>> Gary Hodges wrote:
>>
>>> I have some remote machines w/o internet access.  I get around that by
>>> dialing in a couple times a day, but I've never liked that solution. But
>>> what prompted me to start looking for a solution is...  You all will love
>>> this...  I have a machine on the net behind the firewall of a very large
>>> government organization where I'm not able to use a time server outside the
>>> network.  And, get this, they don't keep the time set on their internal time
>>> server.
>>>
>>> In case anyone is interested, I got a price quote from that UK vendor
>>> this morning.  $1590 for a GPS solution and $995 for a WWVB solution.
>>
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>
> --
> George Sexton
> MH Software, Inc.
> Voice: +1 303 438 9585
> URL:   http://www.mhsoftware.com/
> _______________________________________________
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-- 
Jason Vallery
jason at vallery.net

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