[time-nuts] Strange GPS behaviour

Bob Camp lists at rtty.us
Sun Dec 30 22:47:48 UTC 2012


If you go back far enough in the NIST papers done for the Frequency Control Symposium, you can find a number of them on GPS receivers. One that got a pretty full go through was the (now golden) Motorola timing receiver. They found a number of issues with it. The receiver did get better as the firmware was worked over. 

Any receiver that has not been beat on for timing likely has issues. For what ever reason, the manufacturers of low cost modules don't have the time / equipment / money / interest / people / expertise  to really ring things out. Most firmware issues are found by customers. It is not uncommon to find that the firmware team has a fairly large wall covered with "fix requests". Which ones get worked on will always depend on the money behind the request. Timing is going to be pretty far down the list for most outfits….


On Dec 30, 2012, at 3:09 PM, Fabio Eboli <fabioeb at quipo.it> wrote:

> An update regarding the GPS module,
> simply shielding it from air currents
> improved the things:
> http://www.flickr.com/photos/14336723@N08/8327229820/
> At 48000s I swapped references, hence
> the change in slope.
> I think the poor receiver module
> (Azelio, 20€, I think it can be
> considered cheap :) is not to be blamed
> too much, I mounted it raised  from the PCB,
> and the only thermal contact were the few
> pins used to connect to it, and it was
> exposed to moving air.
> But usually it will be sodered directly
> on the PCB like an SMT component, and
> enclosed into a box.
> Il 2012-12-28 23:27 Fabio Eboli ha scritto:
>> Like I mentioned in a precedent message
>> (answering Magnus) I'm seeing some temp
>> effects on my GPS module, see this message:
>> http://www.febo.com/pipermail/time-nuts/2012-December/073310.html
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