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 <[email protected]> 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
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