[USRP-users] Frequency synching USRP B210

Marcus Müller marcus.mueller at ettus.com
Mon Oct 2 13:23:35 EDT 2017


Hi Daniel,

I'm a bit confused by your wording:

you say you set the clock source to O/B GPSDO and unknown PPS; but PPS
has nothing to do with the clock source, but with the timing source. Can
you confirm that both the time source and the clock source are set to
the GPSDO?

Also, you say you see a rotating constellation – that could be perfectly
fine, depending on how fast that rotates. Could you give us some info
about what your carrier frequency is, what your symbol rate is, and how
fast the constellation is rotating?

Best regards,

Marcus the lesser experienced


On 10/02/2017 08:52 AM, Cho, Daniel J (332C) via USRP-users wrote:
>
> Hello –
>
>  
>
> I am using a USRP B210 with a GPSDO.  All the parts are assembled. 
> When I power up my USRP, I get a green light at the GPS ANT LED for a
> couple seconds before it shuts off.  When I run a program, it
> recognizes that a GPSDO module is installed.  I ran
> query_gpsdo_sensors to make sure that GPS is locked and it is.  When I
> run gnuradio, I make sure to set both USRP sink and source clock
> sources to O/B GPSDO and unknown PPS. 
>
>  
>
> The setup is just one USRP B210 transmitting a BPSK signal from file
> and another USRP B210 receiving the BPSK signal and plotting it on the
> QT GUI sink.  When looking at the constellation plot of the QT GUI
> sink, the constellation is rotating thus the USRPs are not being
> synched.  How can I get the two USRPs synched using the GPSDO?  What
> am I doing wrong?
>
>  
>
> UHD version is 3.9.6.
>
>  
>
> Thanks,
>
> Daniel Cho
>
>  
>
>
>
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> USRP-users at lists.ettus.com
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