If you compare VCXO time with UTC or GPS once a month to an accuracy of 1s (with NMEA or even a time signal and manual pushbutton) and make a correction for the 2.5 million seconds that occurred since the last correction, you'll be better than 0.5 ppm.
Is that good enough ? On Sat, Apr 14, 2018 at 5:59 AM, Hal Murray <hmur...@megapathdsl.net> wrote: > > kb...@n1k.org said: > > The alternative is to plug a USB GPS into the mac and do a bit of code to > > compare things. If you want to pass the gizmo around to your friends …. > that > > can be done. Pretty good ones are “sub $10” delivered. > > USB GPS gizmos generally don't have a PPS and the timing on the NMEA > sentences is generally crappy. (I may be biased by a few bad examples.) > > Does anybody have a list of ones known to work well? > > There is at least one GPS-USB with PPS, the Navisys > GR-601W/GR-701W/GR-801W, > They were hard to get retail. Looks like idealez sells them Taiwan for > $47 > for the 701W (Ublox 7), $50 for the 801W (Ublox 8) (plus shipping). I > haven't tried ordering through them. Gary and/or Mark may have some for > sale. > > ---------- > > Plan B is a GPS breakout and a USB-serial breakout and a few wires. 4x > less > USB jitter if your USB-Serial chip is full-speed. > > I got mine from SparkFun: > Venus GPS with SMA Connector > https://www.sparkfun.com/products/11058 > USB to Serial Breakout - FT232RL > https://www.sparkfun.com/products/12731 > > ---------- > > Google found this. I don't know anything more: > https://www.zti-communications.com/z050-gps-dongle/ > > > -- > These are my opinions. I hate spam. > > > > > _______________________________________________ > time-nuts mailing list -- email@example.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- firstname.lastname@example.org To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.