Julien wrote:
[]
> You're right, I'm in France, but the servers might be everywhere in
> the world, that's why I can't use a radio receiver as a "general"
> solution, and I'm rather looking at GPS receivers.

A simple GPS system is described here:

http://www.david-taylor.myby.co.uk/n...SD-GPS-PPS.htm

It might give you some ideas....

David

Julien wrote:

> Jonathan Buzzard a écrit :
>
>
>>On Fri, 23 Jun 2006 07:12:29 -0700, Julien wrote:
>>
>>[SNIP]
>>
>>>2/ can you advise me some middle-range clocks (several hundred euros
>>>max.) working on Linux, as well as pros and cons regarding the
>>>technology (GPS, radio...) ?
>>>
>>
>>You don't say where you are in the world. However the NNTP posting IP
>>address suggests France, and you mention Euros.
>
>
> You're right, I'm in France, but the servers might be everywhere in the
> world, that's why I can't use a radio receiver as a "general" solution,
> and I'm rather looking at GPS receivers.
>

The Garmin GPS18LVC is available for something like $85 US. An Oncore
M12 timing receiver with evaluation circuit board, is available from
http://www.synergy-gps.com/ for around $200 US. The Oncore used to be
made by Motorola; they discontinued it and it is now made by another
manufacturer. I have an Oncore and have found that it works very well.
More expensive receivers are available with metal cases, switches,
blinking lights etc. They may be worth the extra cost; the evaluation
board I bought doesn't even have holes that would permit it to be
mounted in a box.

Just be certain that the receivers you buy are designed for timing
service rather than navigation and have a Pulse per Second (PPS) output.

Richard B. Gilbert a écrit :
>
> The Garmin GPS18LVC is available for something like $85 US. An Oncore
> M12 timing receiver with evaluation circuit board, is available from
> http://www.synergy-gps.com/ for around $200 US. The Oncore used to be
> made by Motorola; they discontinued it and it is now made by another
> manufacturer. I have an Oncore and have found that it works very well.
> More expensive receivers are available with metal cases, switches,
> blinking lights etc. They may be worth the extra cost; the evaluation
> board I bought doesn't even have holes that would permit it to be
> mounted in a box.
>
> Just be certain that the receivers you buy are designed for timing
> service rather than navigation and have a Pulse per Second (PPS) output.

According to http://time.qnan.org/, the Garmin GPS18LVC looks fine to
me, however I have a few concerns:

1/ I don't want to use my soldering iron. Anyone knows a reseller that
provide something similar to the RS-232 interface at
http://time.qnan.org/ ?

2/ My servers are shipped with RHEL3, which come with a 2.4
pre-compiled Linux kernel and ntpd. I want to avoid any patching and
compilation. What do I need to do to make ntpd read the PPS and the GPS
time? Would the serial module (providing /dev/ttys*) and gpsd suffice?

Thanks a lot for your help.

Julien wrote:
> Jonathan Buzzard a écrit :
>
>> On Fri, 23 Jun 2006 07:12:29 -0700, Julien wrote:
>>
>> [SNIP]
>>> 2/ can you advise me some middle-range clocks (several hundred euros
>>> max.) working on Linux, as well as pros and cons regarding the
>>> technology (GPS, radio...) ?
>>>
>> You don't say where you are in the world. However the NNTP posting IP
>> address suggests France, and you mention Euros.
>
> You're right, I'm in France, but the servers might be everywhere in the
> world, that's why I can't use a radio receiver as a "general" solution,
> and I'm rather looking at GPS receivers.
>
In that case the Garmin GPS18LVC (note the suffix, it's important!) is
almost certainly your best bet:

It works everywhere you can see the sky, it costs less than $100 plus
about an hour with a soldering iron, using USB for power (I've posted
about this previously), and the accuracy is in the single us range.

Terje

--
-
"almost all programming can be viewed as an exercise in caching"