ASHGPS: 4 Oct 2011: !IMPORTANT!  PM3 / PM3.RTK / MMCX Advisory
PM3, PM3.RTK, MMCX Intermittant Failure to Track Sattelite Vehicles

The information contained in this notice is not authorized, approved or official Ashtech LLC information. 

There is an issue with PM3, PM3.RTK (and perhaps MMCX) dropping SV tracking at random times. I believe that this problem started a couple of weeks ago. Beginning last Friday (30 September 2011) reports of this problem have escalated.

The problem does not appear to be fully endemic. The rate of occurrence of this issue is still very low. Multiple receivers in the same location will not all fail. We (iGage) are unable to duplicate this issue at will.

Only the PM3, PM3.RTK and MMCX receivers appear to be affected. All other Ashtech receivers are OK.

The symptoms of this issue are:

o Receiver tracks SV's, then stops tracking, then starts tracking again

o When jobs are post-processed, single observations are broken into multiple occupations

o Post-processed jobs do not fix

o If you are viewing the screen the receiver will appear to be tracking SV’s, then will drop tracking for a moment and then begin tracking again.

o FAST Survey crashes
To the best of my knowledge this problem is not ionosphere or sun-spot related and there is no known tie to a specific space vehicle, orbit, SBAS/WAAS/EGNOS, geographic location or time of day. I believe this issue is a GNSS Firmware issue and I suspect it will be fixed with updated firmware Real-Soon-Now.

Engineers at Ashtech are already aware of this issue and are working 24-7 to find a solution.

When additional information or updated firmware is available, I will immediately send out additional notifications. If you have any additional information, I will be happy to include it with future reports.

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Good survey and mapping to you all!
Mark Silver,
Igage Mapping Corporation,, +1 801-412-0011 x16