[USRP-users] Overrun on 56MHz with B210

Martin Braun martin.braun at ettus.com
Mon Apr 20 14:45:39 EDT 2015


I get those high-pitched noises too -- the upside is I can acoustically
confirm if USB3 or USB2 is being used.

Also, just to point this out: The max clock rate on B2x0 is actually
61.44 MHz, but above 56 MHz, you'll see the effects of the analog filters.

Cheers,
M

On 18.04.2015 08:13, Marcus Müller via USRP-users wrote:
> Hi Jason,
> 
> yes, in most cases, that is a system bandwidth limitation. Many
> controllers just max out; your chipset is usually on the good side[1],
> but that doesn't actually mean that much.
> 
> Also, I know the noise you're talking about -- it happens to my Laptop,
> too, and also on higher rates. I typically hear it when I do something
> CPU intensive, though -- my blind guess is that it's a voltage converter
> that supplies the CPU with power, and is driven at the edge of its
> specs. You're running osmocom_fft in fosphor mode, which means you're
> using openCL; I suppose you're using OpenCL as a means to get more out
> of your CPU, so that would align with my CPU load assumption.
> 
> So, what you can do is first just use the rx_samples_to_file example
> that comes with uhd (look into /usr/[local/]/lib[64]/uhd/examples), and
> write your samples to /dev/null ; if the overflows go away, you're
> CPU-bound, if they persist, you're USB-bound.
> 
> Greetings,
> Marcus
> 
> [1]
> http://www.ettus.com/kb/detail/usrp-b200-and-b210-usb-30-streaming-rate-benchmarks
> 
> On 04/18/2015 04:17 PM, Jason A. Donenfeld via USRP-users wrote:
>> Hi folks,
>>
>> I'm running a B210 over USB3. I seem to be getting buffer overruns
>> when asking for the maximum 56MHz of bandwidth. For example:
>>
>> zx2c4 at thinkpad ~/Desktop/sdr $ osmocom_fft -a
>> uhd,master_clock_rate=56e6 -s 56e6 -f 420e6 -F
>> linux; GNU C++ version 4.9.2; Boost_105600; UHD_003.008.002-0-unknown
>> gr-osmosdr v0.1.4-16-g61184a19 (0.1.5git) gnuradio v3.7.6.1-103-g8ecfd13a
>> built-in source types: file rtl rtl_tcp uhd
>> -- Operating over USB 3.
>> -- 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 56.000000 MHz
>> -- Actually got clock rate 56.000000 MHz
>> -- Performing timer loopback test... pass
>> -- Performing timer loopback test... pass
>> -- Using subdev spec 'A:A A:B'.
>> [+] Selected device: Quadro K2000M
>> OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.....[repeated enormous amounts]
>>
>> Incidentally, when it's overrunning, I can hear a high pitched
>> capacitor noise inside of my laptop (Thinkpad W530, Intel i7-3820QM,
>> C210 chipset), which is a bit funny. Is it possible that the system's
>> USB controller is simply not up to task? Or is this a configuration
>> issue I can address?
>>
>> Thanks,
>> Jason
>>
>> _______________________________________________
>> 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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