3 ms·

>The CSAC improved atomic oscillators a lot more in power than size... but its timekeeping performance is so/so as far as atomic clocks go. Timekeeping of atom

>The CSAC improved atomic oscillators a lot more in power than size... but its timekeeping performance is so/so as far as atomic clocks go. Timekeeping of atomic clocks is still waaaayy better than next-best technologies (like temp-compensated Xtal oscillators). And size/power/$ constraints matter. So CSACs for the win imho.

fsh 1y ago
A $5 GPS receiver runs circles around a CSAC, so the range of useful applications is quite limited.
- nullc 1y ago
  The timing output from a $5 gps receiver isn't particularly impressive. You have to go to pretty long time intervals for a non-timing GPS to win out. Depending on your application those intervals may be thoroughly irrelevant, e.g. using the device as a frequency source rather than a clock. There is also, of course, the issue of infrastructure dependence. Particularly since wireless telephony has moved almost exclusively to GNSS time we're going to have a really bad time if kessler syndrome takes out the GNSS satellites. Edit: Here is an example adev chart for a inexpensive atomic clock vs what appears to be a pretty good timing GPS receiver: https://www.thinksrs.com/images/instr/prs10/PRS10diag2LG.gif https://www.thinksrs.com/images/instr/prs10/PRS10diag2LG.gif So in that case the GPS accuracy only beats out the free running atomic clock at intervals greater than 200,000 seconds or so. Here is a collection of older timing receivers: http://www.leapsecond.com/pages/3gps/gps-adev-mdev.gif http://www.leapsecond.com/pages/3gps/gps-adev-mdev.gif A quick look didn't turn up any cheap non-timing receivers, but my experience is they're pretty bad (I mean relative to atomic standards, of course). There are better timing receivers than the ones charted above, of course, but they are not $5. Their cost is now in the same general ballpark as surplus atomic clocks. Of course, if you have both you can sync one to the other with whatever time constant maximizes the composite performance and have the best of both. (and primary atomic clocks don't have this drift issue, but sadly the days of the occasional sub $1000 5071 showing up on auction sites seem to be over. :P )

fsh 1y ago

A $5 GPS receiver runs circles around a CSAC, so the range of useful applications is quite limited.

nullc 1y ago
The timing output from a $5 gps receiver isn't particularly impressive. You have to go to pretty long time intervals for a non-timing GPS to win out. Depending on your application those intervals may be thoroughly irrelevant, e.g. using the device as a frequency source rather than a clock. There is also, of course, the issue of infrastructure dependence. Particularly since wireless telephony has moved almost exclusively to GNSS time we're going to have a really bad time if kessler syndrome takes out the GNSS satellites. Edit: Here is an example adev chart for a inexpensive atomic clock vs what appears to be a pretty good timing GPS receiver: https://www.thinksrs.com/images/instr/prs10/PRS10diag2LG.gif https://www.thinksrs.com/images/instr/prs10/PRS10diag2LG.gif So in that case the GPS accuracy only beats out the free running atomic clock at intervals greater than 200,000 seconds or so. Here is a collection of older timing receivers: http://www.leapsecond.com/pages/3gps/gps-adev-mdev.gif http://www.leapsecond.com/pages/3gps/gps-adev-mdev.gif A quick look didn't turn up any cheap non-timing receivers, but my experience is they're pretty bad (I mean relative to atomic standards, of course). There are better timing receivers than the ones charted above, of course, but they are not $5. Their cost is now in the same general ballpark as surplus atomic clocks. Of course, if you have both you can sync one to the other with whatever time constant maximizes the composite performance and have the best of both. (and primary atomic clocks don't have this drift issue, but sadly the days of the occasional sub $1000 5071 showing up on auction sites seem to be over. :P )