[USRP-users] 答复: frequency shift of B210
Ralph A. Schmid, dk5ras
ralph at schmid.xxx
Wed Jul 26 10:22:39 EDT 2017
To add my experience, my B210 is off about 1 KHz in the 433 MHz bands. A bit above 2 ppm, probably still covered by the specs, but not the best value for a 6 GHz transceiver :) This was better in the beginning, but I don't know if this came from ageing, or from changes in UHD and FPGA image. It became obvious to me a few weeks ago, when I monitored a 5 GHz ham radio beacon that appeared off for more than 10 KHz.
I have still one question open, does the internal PLL of the B210 lock automatically when it gets a 10 MHz reference directly to the REF input, or does the PLL need to be initialized to start working? Means, when I circumvent the reference switch, not via the SMA input.
From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Derek Kozel via USRP-users
Sent: Wednesday, July 26, 2017 4:03 PM
To: john liu
Cc: 戚科峰(研三 福州); USRP-users at lists.ettus.com
Subject: Re: [USRP-users] 答复: frequency shift of B210
Marcus Leech and Marco have both offered good advice on testing the frequency stability of the B210 against outside references. Have you tried either?
Marcus Muller also asked for additional information about your test setup.
On Wed, Jul 26, 2017 at 2:04 AM, john liu via USRP-users <usrp-users at lists.ettus.com <mailto:usrp-users at lists.ettus.com> > wrote:
Any suggestions is welcome.
On Mon, Jul 24, 2017 at 5:35 PM, john liu <johncorad1988 at gmail.com <mailto:johncorad1988 at gmail.com> > wrote:
Do you have any suggestions about this?
On Mon, Jul 24, 2017 at 9:15 AM, 戚科峰(研三 福州) <qikefeng at ruijie.com.cn <mailto:qikefeng at ruijie.com.cn> > wrote:
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。
发件人: john liu [mailto:johncorad1988 at gmail.com <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 <mailto:USRP-users at lists.ettus.com> ; 戚科峰(研三 福州)
主题: Re: frequency shift of B210
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.
Can you describe your test method?I am not clear for that.
On Fri, Jul 21, 2017 at 10:47 AM, Marcus D. Leech <mleech at ripnet.com <mailto: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 <mailto: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 <mailto:johncorad1988 at gmail.com> > wrote:
internal with TCXO.
On Thu, Jul 20, 2017 at 11:31 PM, Marcus D. Leech <mleech at ripnet.com <mailto:mleech at ripnet.com> > wrote:
On 07/20/2017 02:22 AM, john liu wrote:
What was your tuned frequency in this case?
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 <mailto:johncorad1988 at gmail.com> > wrote:
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?
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