The best method for measuring a fundamental parameter like frequency
drift would be to use a signal source of known (and much-superior)
stability, and use something like uhd_fft with the B210 to observe drift
over time (use the peak-hold feature in the FFT display).
The problem with using the end-application is that it is very very
difficult to "de-embed" the behaviors of the end application from the
parameter you're trying to measure.
On 2017-07-24 10:28, Marcus Müller via USRP-users wrote:
> Dear John,
>
> at this point my recommendation is: Describe your measurement setup in more
> detail, and verify it's useful for measuring the clock quality of the B210,
> and not the of your CC11xx system. In fact, from what you've described, I
> can't really say I understand how this measures the clock offset of the B210
> - instead, it only measures how well the CC11xx works together with your
> software; I'm having a bit of a hard time seeing how you can derive
> statements on the frequency shift from that.
>
> Best regards, Marcus
>
> On 07/24/2017 11:35 AM, john liu via USRP-users wrote:
> HI,all,
> Do you have any suggestions about this?
> thank you.
> best regards
> John
>
> On Mon, Jul 24, 2017 at 9:15 AM, 戚科峰(研三 福州) <qikef...@ruijie.com.cn> wrote:
>
> Hi,Marcus,
>
> we use The B210 as a basestation and cc1120 as the tranceiver of UE.
>
> The B210 uses the Frequency offset estimation algorithm to estimate the
> frequency offset of cc1120 and records it.
>
> there are several UE in the system,UE will receive the B210'signal
> periodically and will send a signal to B210 in another period.
>
> when the phenomenon of the 3.2k frequency shift occured， all UE could not
> receive the signal of B210.when time for UE to send a signal，
>
> B210 would estimate the new frequency shift and found that the Frequency
> offset of every UE shifts 3.2k。So we think the shifting occured in B210
> instead of UE。
>
> best regards
>
> 发件人: john liu [mailto:johncorad1...@gmail.com]
> 发送时间: 2017年7月21日 16:42
> 收件人: Marcus D. Leech
> 抄送: USRP-users@lists.ettus.com; 戚科峰(研三 福州)
> 主题: Re: frequency shift of B210
>
> Hi,Marcus,
>
> We calculated this.
>
> The B210 not only generate a GFSK signal,but also received the signal from
> CC1120.The CC1120 and B210 both work in full duplex mode.
>
> Hi qi,
>
> Can you describe your test method?I am not clear for that.
>
> best regards
>
> John
>
> On Fri, Jul 21, 2017 at 10:47 AM, Marcus D. Leech <mle...@ripnet.com> wrote:
>
> On 07/20/2017 10:08 PM, john liu wrote:
>
> i am sorry.
>
> We generate a GFSK signal with B210 and received the signal with multiple
> cc1120.When frequency shift occurred,the cc1120 can not received the signal.
>
> Also, another b210 has been running for several days without such a jump
> phenomenon.
>
> So, sorry to be a bother, but, where did the 3.2kHz frequency shift
> measurement come from? The CC1120 is just a GFSK demodulating digital
> receiver.
>
> On Fri, Jul 21, 2017 at 9:37 AM, Marcus D. Leech <mle...@ripnet.com> wrote:
>
> No i mean what were you measuring?
>
> Were you using an external signal generator and what were its specs?
>
> Sent from my iPhone
>
> On Jul 20, 2017, at 9:09 PM, john liu <johncorad1...@gmail.com> wrote:
>
> HI Marcus,
>
> internal with TCXO.
>
> On Thu, Jul 20, 2017 at 11:31 PM, Marcus D. Leech <mle...@ripnet.com> wrote:
>
> On 07/20/2017 02:22 AM, john liu wrote:
>
> What was your tuned frequency in this case?
>
> Hi,Marcus,
>
> It is 433.05Mhz
That's about 7PPM.
What was your signal source?
On Thu, Jul 20, 2017 at 11:46 AM, john liu <johncorad1...@gmail.com>
wrote:
Hi all,
We used B210 with TCXO,and run about 2 hours , a 3.2K frequency shift
occurred when the temperature did not change significantly.Is it a
normal?
How can we improve this situation?
thank you.
best regards
John
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