11 Jul
2024
11 Jul
'24
5:42 p.m.
On Thu, Jul 11, 2024 at 08:00:26AM -0000, JPichel wrote:
If anyone finds it useful, I have found using the
internal clock on the B205mini works fairly well, Comparing it against using the LBE-1420
external reference from Leo Bodnar, which reports up to 0.000001 ppm, there isn't that
much change in terms of frequency error. Checking the position of the FCCH on the spectrum
analyzer (which should be fc + 67.7 kHz), in my case I have:
- Internal clock -> Δf = 220-130 Hz.
- External clock -> Δf ~= 130 Hz.
I would recommend using a disciplined oscillator anyways because the internal clock
experiences frequency drift, probably caused by changes in temperature.
If the B205mini's clock is anything like the B210...
Just my twopence on this, when I started out with Osmocom, I used to work with
a B210 for months and was completely happy. Randomly one day nothing worked
anymore and I thought it was my fault. It was solved by a good clock source.
(Another part of that journey was realizing that the B210 can have a GSPD0
connector even if it doesn't have a GPS receiver inside.)
So the B210 is also not guaranteed to give you a non-working clock,
if you catch my drift =)
I mean that even if it seems reliable, it's still quite possible that the
season is just right to go without a proper clock, but come wintertime...
Reminds me of the XTRX project, that put a very precise internal clock on its
SDR specifically for the selling point of not needing an external clock for
mobile communications, like other SDRs do. (wow that was SEVEN years ago???)
~N