[ntp:questions] Re: All my servers rejected

Chris Stenton jacs at gnome.co.uk
Fri Jan 9 11:08:48 UTC 2004


At $30 I would go for the RadioShack GPS if it can generate a 1PPS.

I have both  Motorola M12 Timing and Non-Timing evaluation kits, both
generate 1 PPS signals. I have found that when connected to a bulk standard
motherboard the "M12 Timing" version is more accurate but nothing to write
home about. I think to get the best out of it you need a motherboard with
better crystals than you get on a std board.

Strangely, I have found that the "M12 Timing" picks up less satellites than
the non timing version using the same puck antenna. At my location I can get
24/7 coverage with the "non timing" but not the "M12 Timing" version. I've
got the external antenna but its cold and wet outside so its still in its
box.

Chris


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message
news:Es-dnWKI0dwWlGOiRVn-jg at comcast.com...
> I believe that the RadioShack GPS receivers are navigation rather than
> timing.  Synergy Systems sells a Motorola M12 Timing Evaluation kit for
> $198.  This includes a circuit board with the M12 and support
> components, a wall wart for DC power, a hockey puck antenna with cable
> and an RS232 cable.  It has a one PPS output in addition to choice of
> NMEA or Motorola Binary output formats.  You need to mount the circuit
> board in a box of some sort and hook it up to a computer.
>
> I had hoped to have the one I've ordered in hand by now but no such
> luck; I just talked to Synergy and they haven't shipped it yet. <sigh>
>
> The RadioShack receiver would still be far superior to a satellite
> connection with two to three second latency.  A lot depends on how
> closely he needs to synchronize.
>
>
> Harlan Stenn wrote:
>
> >I recommend the following:
> >
> >- Can you afford $200 for a GPS clock?  I gathern RadioShack is closing
out
> >  some (apparently tolerable) GPS receivers for about $30...
> >- do what you can to get a local, reliable frequency source, so you can
> >  continue to have stable time when your link is down.
> >- use iburst and burst (in your specific case - in most cases
> >  burst is Unfriendly)
> >- use your pppup/pppdown scripts (or whatever) to handle enabling and
> >  disabling your ntp associations as your connection goes up and down
> >
> >This is somewhat discussed on twiki.ntp.org .  I would be Happy to see
> >more info there.  Please help.
> >
> >H
> >
> >
>





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