Typical L1 antenna delays range from 20 to 70 ns. I know of only one antenna for which a delay is given by the vendor and the technique used was just to measure the electronic delay ie by injecting a signal into the circuit. To do it properly, you need a setup in a microwave anechoic chamber with transmitting antenna etc. The practical difference may be small though, 1 or 2 ns ( sample of one antenna!).
Cheers Michael On Sat, 27 Feb 2021 at 11:42 am, John Ackermann N8UR <j...@febo.com> wrote: > They're claiming "even better than" 5 ns for relative time, which given > the 4 ns jitter seems at least sort-of reasonable. But until someone > shows me otherwise, I'm still thinking that getting better than 25 ns > absolute accuracy is a pretty good day's work. > > John > ---- > > On 2/26/21 5:26 PM, Bob kb8tq wrote: > > Hi > > > > I can’t think of many antennas (multi band or single band) that claim to > know their > > delay to < 5 ns. Simply having a *differential* delay spec of < 5 ns is > quite good. > > Same thing with delay ripple, you see specs out to around 15 ns on a lot > of antennas. > > None of this is getting you to the actual total delay of the antenna. > It’s a pretty good > > bet that number is a bit larger than either of these. > > > > Some of the ripple probably comes out in the standard modeling. I’m not > sure that > > the differential delay is taken out that way. Total delay, not taken out > in any obvious > > fashion ( at least that I can see). If the F9 has a built in antenna > database, that’s not > > mentioned in the doc’s. Any benefit from the corrections would have to > be part of > > post processing. > > > > No, that’s not the same as talking about the F9 it’s self doing X ns, > but it would be part > > of any practical system trying to get close to 5 ns absolute accuracy. > > > > 5 ns *relative* accuracy between two F9’s? I probably could buy that if > the appropriate > > one sigma / on a clear day / with the wind in the right direction sort > of qualifiers are > > attached. > > > > Bob > > > >> On Feb 26, 2021, at 4:27 PM, John Ackermann N8UR <j...@febo.com> wrote: > >> > >> It's interesting that they talk about the F9 receivers offering 5 ns > absolute time accuracy. Does anyone know of tests confirming that, and > what sort of care was required in the setup to get there? > >> > >> John > >> ---- > >> > >> On 2/26/21 9:34 AM, Robert LaJeunesse wrote: > >>> FWIW. No detailed content, and a rather quick read. "Five key trends > in GPS". > >>> https://www.u-blox.com/en/blogs/insights/five-key-trends-gps > >>> _______________________________________________ > >>> time-nuts mailing list -- time-nuts@lists.febo.com > >>> To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
