On 1/22/2018 4:38 PM, Paride Legovini via time-nuts wrote: > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver.
As others have pointed out, NTP over the internet isn't usually more accurate than several tens of microseconds, so you have a lot of flexibility in the receiver you choose. If you need something that's simple to interface, has RS-232 polarity signals, and is generally plug-and-play, the Garmin GPS 18x LVC is a good choice. It's robust, compact, and easy to wire to whatever device you want: in my case, I use a USB-A male plug connected to a USB port on my time server to provide the required 5V power and have the serial and PPS lines connected to the server's hardware serial port. It's not strictly a timing receiver with a position hold mode, but it does produce a PPS output +/- 1 microsecond, and can do "position averaging" so it doesn't drift around more than a few meters when stationary. It can output data in either NMEA format or the Garmin binary format, which is well-documented and supported by GPSd. Garmin's made the receiver for many years and has generally worked out the kinks with a bunch of firmware updates over the years. Another alternative is the rather older Motorola Oncore UT+ receivers one can get on eBay for about $15 USD. No longer supported by the manufacturer and with hardware of unknown age, it might not be the best choice for critical systems. Still, they're true timing receivers with sawtooth correction, are easy to power with 5V, output TTL serial (so a MAX(3)232 can easily convert the data to RS-232 polarity) and a PPS signal, and are well-supported by NTPd. The Oncore driver for NTPd is a bit chatty in terms of what it logs every second, but that's easy enough to deal with. They're cheap enough to get a few to play with. Cheers! -Pete -- Pete Stephenson _______________________________________________ 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.
