What antenna are you using and where is it located? I have the TruePosition with a Motorola PCTEL 8508851k66 antenna on a windowsill with a ground plane under the antenna and it generally sees 4-7 sats. I have seen some holdovers but it has been better after running for a while and doing a survey. The TruePosition seems to switch between modes 0 and 1 as new sats come into view. The 10 MHz out does not change that I can see when this happens.
Regards, Mark W7MLG On Fri, May 11, 2018 at 10:56 AM, gandalfg8--- via time-nuts < [email protected]> wrote: > I've had one of the cheap TruePosition GPSDOs running here for the past > week, this is the earlier version with the Bliley oscillator, and as Mark > reported have been seeing what I consider to be excessive holdover reports > from Lady Heather. > > At 55 degrees north the number of Sats visible can be a bit variable, and > with this running on an indoor antenna probably even more so, but I've run > plenty of other GPSDOs here in similar fashion and have not seen this > before. > > I've not been running Lady H in logging mode, just running in the > background when this PC is on so all a bit hit and miss, but I have been > seeing holdover reports every day and with the time building up as the day > goes by. The time never exceeds 5 or 6 minutes though so if it was just > being used as a reference without monitoring the status this could easily > go unnoticed. > > The LMU300 Location Measurement Unit that this comes from will need to > track four Sats for positioning purposes, and the manual for that does > state that the LMU300 will indicate a holdover alarm when "The LMU cannot > lock on to the minimum number (4) of GPS satellites and the LMU GPS > receiver board has been in holdover for over 15 minutes", and I had started > to wonder if the firmware in the GPSDO might also be treating less than > four Sats tracked as a holdover situation. > > Earlier this afternoon I happened to catch it with between three or four > Sats being tracked and it did seem to be dropping in and out of holdover as > the number varied, once the number of tracked Sats increased again and > stayed there, it's been six for some time now, it settled down again and > hasn't returned to holdover since. > > Hardly the stuff of scientific observation I know, and I need to start > logging what's happening, but it does seem more likely now that these units > could be reporting a holdover event when the number of tracked Sats drops > below four. > > Nigel, GM8PZR > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
