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

Oliver Wayne olivergwayne at gmail.com
Tue Oct 31 13:15:05 EDT 2017


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?

On Mon, Oct 30, 2017 at 3:28 PM, Oliver Wayne <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>
> 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 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> 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!
>>>
>>>
>>> _______________________________________________
>>> 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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