Hi I would suggest that killing off anything that’s unused is a really good idea, especially when switching to a new module. You eliminate a lot of weird corner case issues that you *really* don’t want to find out about ….
Bob > On Feb 9, 2022, at 10:57 AM, Andy Talbot <andy.g4...@gmail.com> wrote: > > Yes, I had to disable the GSV sentence to get the data flow down to a level > that could be sent at the lower speed. > I'm only using GPRMC, so all the others could be removed as well, but as > GPRMC comes first in the block every second, there's nothing to be gained > from killing any of the others sentences. > > I did fall foul once of a changed format. Originally I wrote for an RMC > string that just gave integer seconds. On using my code with a later > module it failed, and I spotted that it was sending decimal seconds, so had > to rewrite my PIC code to cope with that. > Then later, using other module types, GPRMC became GNRMC to cope with > Glonass etc. so that was another change needed. > > Andy > www.g4jnt.com > > > > On Wed, 9 Feb 2022 at 15:49, Bob kb8tq <kb...@n1k.org> wrote: > >> Hi >> >> In terms of upgrading the GPS module(s): >> >> You might want to look at just *what* NMEA messages are being used. >> While the format is “standard” it’s not quite dead nuts in some cases. >> Vendors get to add this and that and it still is NMEA. Converting from >> one family to another is not always easy. >> >> I would also want to check the GPS antenna at the remote site. They >> don’t last forever. Flakey sat signals can drive a module a bit nuts. >> >> GPS modules have gotten pretty cheap over the years. If this is a long >> drive / crazy access sort of thing, redundancy is not as expensive on >> the module (or antenna) side as it once was. >> >> Bob >> >>> On Feb 9, 2022, at 4:36 AM, Andy Talbot <andy.g4...@gmail.com> wrote: >>> >>> I run a set of microwave beacons on a remote site that transmit data >> modes >>> whose Tx timing is controlled from GPS. They were installed some 20 >> years >>> ago and used a Garmin GPS25-LVS module to deliver NMA and 1 PPS signals >> to >>> all five individual controllers. >>> >>> After a power outage that lasted a couple of days, the beacons fired up >> but >>> it was clear, after a couple of days timing was corrupted. Each beacon >> has >>> slightly different controller firmware, and by monitoring the resulting >>> corrupted modulation it could be determined what was wrong. No PPS >>> signal was present - which killed modulation on two of them. NMEA timing >>> data was present but the time being reported was out by several seconds, >>> rendering the data signal transmitted undecodable by most people. >>> >>> I went up to the remote site to recover the old hardware and am in the >>> process of replacing the timing source using a Ublox NEO-6. Since all >> the >>> beacons were originally designed based on 4800 baud NMEA, the Ublox was >> set >>> for this for backwards compatibility with the Garmin and the >> configuration >>> saved in NV ram. >>> >>> Now the query I have. I had assumed it was a 1024 week rollover that >>> killed the Garmin, but on testing teh module when I returned home, after >> a >>> longer than normal initialisation period it DID start outputting the >>> correct date and time, with PPS present. So the initial reboot failed, >>> even after a couple of days attempt, but after a power cycle it worked. >>> >>> I'm puzzled by that behaviour. Is anyone here familar with the GPS25 >>> family, dating from the turn of the millennium? >>> >>> As an aside, a Jupiter TU60 GPS module was also in use on site, >> delivering >>> a GPS locked 10kHz signal. This I used to lock a 10MHz reference in >>> "Probably the Simplest GPSDO Possible" http://g4jnt.com/SimpleGPSDO.pdf >>> That module, which is not a lot newer than the Garmin, did appear to have >>> survived the reboot as the resulting frequencies of the beacons were >>> spot-on when they returned with their modulation faults. However, in the >>> spirit of doing the job properly, it too is being replaced with a >>> Leo-Bodnar mini GPSDO. >>> All beacon details at scrbg.org >>> >>> >>> Andy >>> www.g4jnt.com >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.