I have a hAP ac2 on a telescope tripod. I need an accurate time source when not internet connected (at that point this is used as an access point to connect the telescope’s NUC and my laptop, phone, etc.). I actually do not know how accurate, but I figure GPS is better than the NUC’s RTC.
I see that RouterOS has a gps module. Most documentation seems to address use with LTE based systems.
Is it possible to put one of the many USB GPS dongles in and let it derive time (and even location) from it, then server it up via NTP (The latter looks supported).
If so, is there a list of supported GPS devices (or even someone who can suggest one you have used and know works)? Preferably one of minimal size, no cables if possible, as it’s all strapped to a tripod.
MT support for GPS is partial … in a sense that with supported GPS modules it is possible to obtain location. What doesn’t work is to use GPS module as source for accurate time … because it takes much more than reading NMEA0183 telegrams to get accurate time (time stamp precision in telegrams is 1 second, but then there’s systematic offset because telegrams are not transmitted at beginning of second and offset is not determined) and there’s jitter (due to imprecise timing of telegram transmission and parsing the output). Real GPS time receivers use 1PPS signal which determines start of second with precision better than a microsecond. And both GPS module and receiving device have to offer hardware support for 1PPS interface, this is not SW-defined.
In reality it’s better to use NTP over whatever WAN technology available than simple GPS receivers.
Thank you, @mkx. At home I can run NTP, but when at an astronomy dark site there’s at best cellular, sometimes not that, but I’ll look into something maybe to sync with the phone’s time so at least with a cell signal I can get it to work. It’s not worth a cellular subscription for the rare times.