Slightly related to the recent threads on GPSDO, I have been plotting a bunch of statistics from an M12+ for about 10 months
Every five minutes I grab the the number of SVs visible, tracked, signal strength of each bird, and average signal strength of the tracked birds. I have plots of the full run and the most recent 36 hours at http://www.febo.com/time-freq/plots/oncore.html. From those plots, it's pretty apparent that there's plenty of signal strength all the time. I ran some simple tests on the log data and the lowest number of SVs tracked over that time was 5. The lowest signal strength (average of the raw numbers for each tracked bird reported by the M12+) was 31.43, and there were only three strength readings below 40. One thing I haven't tracked is the number of times the receiver lost lock; I should figure out how to add that to the data. However, given the minimum number of birds tracked, I doubt the receiver came unlocked very often. I have a pretty decent antenna setup -- a roof-mounted Motorola 2000 antenna fed with about 60 feet of LMR-400 into an HP 2 way splitter, then another 12 feet of LMR-400 to an HP 4 way splitter, then 6 feet of LMR-240 to the receiver. There are some trees in the way, but overall there's a decent horizon. I know a lot of cell sites don't have the luxury of a clear sky view, but given these results from a decent antenna, I wonder if holdover performance continues to be a significant factor in GPSDO design? John _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
