[USRP-users] 答复: frequency shift of B210

mleech at ripnet.com mleech at ripnet.com
Mon Jul 24 12:09:56 EDT 2017


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) <qikefeng at 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:johncorad1988 at gmail.com] 
> 发送时间: 2017年7月21日 16:42
> 收件人: Marcus D. Leech
> 抄送: USRP-users at 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 <mleech at 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 <mleech at 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 <johncorad1988 at gmail.com> wrote: 
> 
> HI Marcus, 
> 
> internal with  TCXO. 
> 
> On Thu, Jul 20, 2017 at 11:31 PM, Marcus D. Leech <mleech at 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 <johncorad1988 at 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 

_______________________________________________
USRP-users mailing list
USRP-users at lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

_______________________________________________
USRP-users mailing list
USRP-users at lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20170724/cccf47eb/attachment-0002.html>


More information about the USRP-users mailing list