[USRP-users] B210 RF DC Offset Calibration Failure

Ian Buckley ianb at ionconcepts.com
Tue Dec 16 18:56:47 EST 2014


Nathan, 
I thing this is a perfectly reasonable question given that ADI specs the radio as supporting this rate. I have filed a bug on this and I'll try to get someone to work on it ASAP to get a definitive answer.
The bug is #649 incase you have a conversation with any Ettus support folks in the future on this topic.
I, BTW see the same error message as you with current UHD and a B210.
-Ian

On Dec 16, 2014, at 2:58 PM, "Perelman, Nathan" <nperelman at lgsinnovations.com> wrote:

> So is there no way to reliably sample at 61.44 MHz from a B210?
> -Nathan
>  
> From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Perelman, Nathan via USRP-users
> Sent: Monday, December 1, 2014 6:59 PM
> To: Ian Buckley
> Cc: usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] B210 RF DC Offset Calibration Failure
>  
> As advertised by the driver, the error does go away when I request a master clock rate of 56 MHz. Other values between 56 and 61.44 MHz did not work (I tried 57, 58, and 60). I was hoping to be able to sample at 61.44 MHz for my application.
> -Nathan
>  
> From: Ian Buckley [mailto:ianb at ionconcepts.com] 
> Sent: Monday, December 1, 2014 6:16 PM
> To: Perelman, Nathan
> Cc: usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] B210 RF DC Offset Calibration Failure
>  
> This is a vague answer since I've never worked on this aspect of AD9361 and someone may respond with a better response…..
>  
> My recollection is that despite the actually radio being spec'ed to 61.44MHz, experience demonstrated that some of the internal algorithms that perform calibrations start to have problems converging above 56MHz, which generally results in larger elapsed times before the device is ready to by used after configuration. Thus the origins of the warning message UHD gives for rates >56MHz. I don't recall hearing a good reason "why" this should be so from any ADI engineering folks.
>  
> So perhaps slow to converge manifests as failed to converge for some possible configurations? What happens if you back it off a little from the limit..say 61.0HMz?
>  
> -Ian
>  
>  
> On Dec 1, 2014, at 1:58 PM, "Perelman, Nathan via USRP-users" <usrp-users at lists.ettus.com> wrote:
>  
> 
> I’m seeing this error attempting to use a B210 with a master clock rate of 61.44 MHz. This is with UHD 3.8.0. I’ve been just trying to test it out with the benchmark_rate application, but this is what happens:
>  
> $ ./benchmark_rate --rx_rate 61.44e6 --channels 0 --args "master_clock_rate=61.44e6" --rx_cpu=sc16
> linux; GNU C++ version 4.8.3 20140624 (Red Hat 4.8.3-1); Boost_105500; UHD_003.008.000-0-unknown
>  
>  
> Creating the usrp device with: master_clock_rate=61.44e6...
> -- Operating over USB 3.
> -- Detecting internal GPSDO.... Found an internal GPSDO
> -- Initialize CODEC control...
> -- Initialize Radio control...
> -- Performing register loopback test... pass
> -- Performing register loopback test... pass
> -- Performing CODEC loopback test... pass
> -- Performing CODEC loopback test... pass
> -- Asking for clock rate 61.440000 MHz
>  
> UHD Warning:
>     The requested clock rate 61.440000 MHz may cause slow configuration.
>     The driver recommends a master clock rate less than 56.000000 MHz.
> Error: RuntimeError: [ad9361_device_t] RF DC Offset Calibration Failure
>  
>  
> I get the same error for other rates I’ve tried in excess of 56 MHz. Any idea what causes this error and what I could do to resolve it? Thanks.
> -Nathan
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>  

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