On 12/16/2016 1:54 PM, wb6bnq wrote: > Hi Pete, > > Are you really at an altitude of 645 meters ?
Yes. That's the result of multiple surveys over a week a year or two ago. I'm pretty sure the altitude hasn't changed since then. :) I think Lady Heather shows the altitude as that above the WGS84 geoid rather than above sea level, right? I'm trying to resolve some discrepancies in reported altitude between my handheld Garmin eTrex 20, Oncore UT+, and Thunderbolt (the Oncore and Thunderbolt share a split signal from the same antenna). > Also, it seems that your oscillator gain (currently at -5 Hz/v) may not > be set right ? That's the default for the Thunderbolt. I've tried tuning it a bit to other values but it runs reasonably well at that value so I stick with it. > Have you checked the power supply voltages and observed them on an > oscilloscope to see if they are relatively clean and free of spurious > junk ? I've checked them with a multimeter and, while not dead-on at +5, +12, and -12V, they're within the acceptable range mentioned in the Thunderbolt manual. I have an oscilloscope and will probe them later today when I get home from work. > The available number of SATS is quite low and could be a matter of > concern. The antenna is in a poor location, facing to the northwest. It's the best I can do in this apartment, and the number of satellites seen is typical for this location. What's interesting is that the weird transients would occur at least once every few hours over the last two days, but when I switched to using a hardware serial port (as opposed to a genuine FTDI USB-to-serial adapter connected to a hub) there hasn't been anything for the last 7 hours. I made no other changes to the setup. The adapter had been working fine with no issues for at least a year and I was using it for other devices as well with no problems. I had turned off the Thunderbolt for a few months to save electricity (with my PhD studies nearing a close I needed to focus and take time off from amateur radio stuff) and just turned it on again in preparation for the leap second. It's possible this may have simply been a communication error between the Thunderbolt and the computer. I'll do more tests to find out. Cheers! -Pete _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.