Dear all,
I would be very cautious attempting to derive the frequency accuracy of a piece
of equipment against its master oscillator specification, as any function
subservient to its nominal frequency and temperature drift over time
specification will vary across product.
For information I have a B200 and B210 which after 30 minutes or more of warm
up will generate RF carriers around 2.4 GHz with up +/- 10 KHz difference
unless externally 10 MHz stabilised. This concurs with other comments.
Best regards,
David GD4FMB
>
> On ,Wed Apr 10 2024 03:01:30 GMT+0100 (British Summer Time), Marcus D.
> Leech <patchvonbr...@gmail.com> wrote:
>
> ---------- Original Message ----------
>
> On 09/04/2024 21:48, John Ackermann N8UR via USRP-users wrote:
> > I'm not
> sure about this particular unit, but typically if a crystal
> > oscillator
> datasheet lists an "accuracy" specification, that is over a
> > time period
> that takes into account the long-term frequency drift
> > ("aging") that
> affects almost all oscillators. Sometimes the accuracy
> > is specified
> over a period of years, especially if the oscillator
> > doesn't have a
> frequency adjustment input. In oscillators that can be
> > tweaked, it
> might be stated as an aging rate of some value per day,
> > week, or month.
> >
> > In inexpensive oscillators, the "stability" number usually refers to
> > short-term change due to temperature and other environmental factors.
> >
> In more expensive oscillators, stability is usually specified over
> >
> various averaging intervals, say from 1 second to 10K seconds.
> >
> >
> Sometimes accuracy is also expressed as a combination of time and
> >
> temperature range, which gives the most conservative result.
> >
> > John
> >
> ----
> See also Allen Deviation plots....
>
>
> >
> > On 4/9/24 21:19, Timothy J.
> Salo via USRP-users wrote:
> >> Hi,
> >>
> >> I'm writing a "Getting Started"
> guide for our research group. When I
> >> got to the GPSDO section, I had
> difficulty in figuring out the frequency
> >> stability and the frequency
> accuracy of the B210.
> >>
> >> At least the early versions of the B210 used a
> CTS Electronic Components
> >> 520L20DA40M0000 TCXO. The datasheet for this
> TCXO says it has a
> >> frequency _stability_ of +/- 2.0 ppm over an
> operating temperature range
> >> of -30C - +85C.
> >>
> >> The CTS website
> states that their TCXO exhibit: "Stratum 3 Performance;
> >> ±4.6ppm
> overall, ±0.28ppm over -40°C to +85°C". Am I correct in
> >> concluding
> that this is the frequency _accuracy_ of the TCXO used in
> >> the B210?
> Does this translate directly into the frequency _accuracy_
> >> of the B210?
> >>
> >> The B210 datasheet states a frequency _accuracy_ of +/- 2.0 ppm. Is
> >> is a typo, and should the datasheet actually say frequency _stability_?
> >> Or, did someone conclude that over a reasonable operating temperature,
> >> the effects of temperature outweigh any inaccuracy in the frequency
> >>
> of the TCXO?
> >>
> >> Anecdotally, I have heard that one organization found
> that three of
> >> their four B210s, when operating as a 5G base station,
> were unable
> >> to connect with commercial off-the-shelf cellular handsets,
> unless
> >> an external GPSDO was used with the B210. Does anyone have any
> idea
> >> what frequency accuracy is expected by cellular handsets?
> >>
> >>
> So, does anyone know what the frequency _accuracy_ of the B210 is, in
> >>
> the absence of a GPSDO? Or, should I just use the +/1 2.0 ppm figure?
> >>
> >> Thanks,
> >>
> >> -tjs
> >> - - - -
> >>
> >> [1]
> >>
> https://www.ctscorp.com/Files/DataSheets/Passives/FCP/TCXO/TCXO-520-datasheet.pdf
> >>
> >>
> >>
> >> _______________________________________________
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> >
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