Just out of curiosity, how many PSc/laptops/servers does it take to run a radio station?
[email protected] said: > What NTP software should be used on Windows OS machines? Linux servers? There is a version of ntpd available for Windows. Meinberg builds and distributes it. Most Linux distros come setup to use ntpd with servers from the pool. It's impolite to use the pool (or other servers) if you have more than a handful of clients. Setup a pair (or more) of servers to use the pool and point your internal clients at them. You may be able to configure your dhcp server to tell clients which NTP servers to use. > desktops and servers: better NTP configuration NTP checks: at least hourly? I treat things like "at least hourly" as an indication of suspicious software. There are a lot of packages that poll a server and smash the local clock. They usually have an option to set how often to do that. The real key to decent timekeeping on a computer is to calibrate the crystal offset. Modern OSes have a way to set that knob. ntpd calls it drift. It's saved in a file so it can be reloaded on reboot. (Units are PPM.) ntpd adjusts the polling interval automagically looking for the bottom of the adev graph with a cap at 1024 seconds. The crystal is a thermometer. On modern systems, the temperature depends on the workload as well as the air conditioning. > * some systems are on in-house Ethernet; others on in-house wi-fi How good is your WiFi? (mine is crappy) The other consideration in this area is how good is your Internet connection? If it is saturated by a big download or upload, that may confuse ntpd. ntpd assumes the network delays are symmetric. It also filters out quirky samples. The filter uses the last 8 samples so you need a long-enough download/upload to cause problems. (There is a huffpuff option to try harder.) > â no smearing (minimum requirement) Beware of Google's NTP servers. > â accurate leap second display (desirable but unlikely to be > achievable) What would anybody do if they saw a blinking "LEAP" on a display? The NTP protocol distributes a leap-tonight indication. It's fairly easy to query your ntpd server to see if that will happen. NIST and others distribute a file with a list of leap seconds, including the next one if it has been announced. (ntpd can use that file to introduce local leaps and/or override leaps from the net.) > ⦠use time.nist.gov <http://time.nist.gov/> and similar > higher-quality NTP servers They are high quality in the legal sense, but the network between you and the server may add a lot of noise. You may be able to find good local servers. Ask around. What do the local geeks use? (There is probably an overlap between radio geeks and network geeks.) ----------- How often does your internet link go down? ----------- The package that provides ntpd probably includes ntpq. You can use it see which servers ntpd is using, the round drip time to each server, and the offset to each server. Try the peers command or ntpq -p <server> (defaults to localhost). ntpd is a server as well as a client. You can setup one system to monitor all the other systems you are interested in. In your config file, add a server line with noselect. That way, ntpq -p on one system will give you a quick health indication of the others. You can also collect make graphs and/or will have logs if you want to investigate glitches. ----------- You can setup a Raspberry Pi with a GPS as a time server. That will give you a good place to stand if you want to see how your NTP servers are doing. (You need a GPS Hat. The low cost GPS mice that connect via USB don't provide PPS and even if they did, USB adds a lot of noise.) It may not work with the antenna indoors. Maybe near a window? Or for a temporary hack, use a long extension cord and long ethernet cable and put it outside. -- These are my opinions. I hate spam.
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