On 10/04/2024 06:57, drtay...@manx.net wrote:
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
10kHz for a 2.4GHz carrier is more than you would expect from a 2PPM
master oscillator. The fact that it gets better with
a better external oscillator suggests that there's an issue with the
on-board master oscillator TCXO, and not some weirdness
in PLL synthesizer settings, for example.
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
>>
>>
>>
>> _______________________________________________
>> USRP-users mailing list -- usrp-users@lists.ettus.com
>> To unsubscribe send an email to usrp-users-le...@lists.ettus.com
> _______________________________________________
> USRP-users mailing list -- usrp-users@lists.ettus.com
> To unsubscribe send an email to usrp-users-le...@lists.ettus.com
_______________________________________________
USRP-users mailing list --usrp-users@lists.ettus.com
To unsubscribe send an email tousrp-users-le...@lists.ettus.com
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-le...@lists.ettus.com
