[USRP-users] Fwd: Removing DC offset on USRP B200

Marcus D. Leech mleech at ripnet.com
Tue Oct 31 13:19:59 EDT 2017


On 10/31/2017 01:15 PM, Oliver Wayne wrote:
> Another thought I had -- because I don't anticipate my waveform 
> changing much, is there a way to pre-record my waveform and transmit 
> it continuously, which if I understand the problem correctly would 
> avoid the underruns?

Sure, just record it in a file-sink, and then play it back from a 
file-source.


>
> On Mon, Oct 30, 2017 at 3:28 PM, Oliver Wayne <olivergwayne at gmail.com 
> <mailto:olivergwayne at gmail.com>> wrote:
>
>     Hi Marcus,
>
>     I switched to performance mode and got the same results. I'm
>     running LDXE on this computer, so I changed it by editing
>     /etc/init.d/cpufrequtils and setting GOVERNOR="performance", then
>     using sysv-rc-conf to deactivate on-demand.
>
>     On Mon, Oct 30, 2017 at 3:01 PM, Marcus D. Leech
>     <mleech at ripnet.com <mailto:mleech at ripnet.com>> wrote:
>
>         On 10/30/2017 02:54 PM, Oliver Wayne wrote:
>>         When I run perf top, I get libuhd.so.3.11 and libc-2.23.so
>>         <http://libc-2.23.so> taking up about 15% and 21%
>>         respectively, rising over time. This is at 10Msps. any
>>         thoughts? I've tried a few other things like setting
>>         otw_format=sc12 and setting the frame size higher, but I
>>         haven't had any success.
>         Could you try running your CPU in "performance" mode, rather
>         than the power-saving 1.6GHz mode that it is apparently
>         running at?
>
>
>>
>>         On Tue, Oct 24, 2017 at 3:42 PM, <mleech at ripnet.com
>>         <mailto:mleech at ripnet.com>> wrote:
>>
>>             You could perhaps do a "perf top" and see what's
>>             consuming time.
>>
>>             The Gnu Radio signal source blocks are not screamingly
>>             efficient, so it may be that they just aren't keeping up,
>>             although at 4Msps, you wouldn't expect them to be too
>>             stressed.
>>
>>             On 2017-10-24 15:12, Oliver Wayne via USRP-users wrote:
>>
>>>             Apologies for not forwarding to the full list. I'm
>>>             attempting to run the attached flowgraph with the
>>>             following hardware, but getting underflows.
>>>             I have 8 GB of RAM, so don't think that's a problem.
>>>             Running lspci | grep -i usb, I get the following output
>>>             00:1a.0 USB controller: Intel Corporation 6 Series/C200
>>>             Series Chipset Family USB Enhanced Host Controller #2
>>>             (rev 04)
>>>             00:1d.0 USB controller: Intel Corporation 6 Series/C200
>>>             Series Chipset Family USB Enhanced Host Controller #1
>>>             (rev 04)
>>>             I've attached a copy of cpuinfo.
>>>             Thanks!
>>>
>>>             _______________________________________________
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>>
>>
>
>
>

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