Just throwing it out there, but have you looked at rfnoc-fosphor ?
I mean capturing and processing large bandwidth spectrum and
decimating it to low bandwidth data is kind of exactly what it does.
Cheers,
Sylvain
On Tue, Feb 19, 2019 at 4:19 PM Jonathon Pendlum via USRP-users
<usrp-users@lists.ettus.com> wrote:
>
> Hi Ramazan,
>
> The VectorIIR RFNoC block implements a vector of low pass single-pole IIR
> filters. The idea is that the spectral content of each FFT bin in the time
> direction is low frequency enough that you can low pass filter (VectorIIR)
> and decimate (Keep one in N) without significant loss of information.
>
> Jonathon
>
> On Tue, Feb 19, 2019 at 11:30 PM Jason Matusiak
> <ja...@gardettoengineering.com> wrote:
>>
>> Ramazan,
>>
>> The timeout channel 0 error is using a timeout that RFNoC is throwing.
>> There is a timeout built in that can be ignored if you are purposely
>> dropping a bunch of samples in the RFNoC domain (which I do in a few
>> flowgraphs). If you dig through the mailing list, someone pointed to where
>> in the code this gets printed; they comment it out so they don't have to see
>> it. It is pretty annoying to me when I am trying to drop samples on
>> purpose, but I haven't commented it out since I want to see it if I wasn't
>> trying to drop samples. My money is on your keep-1-in-n tripping this up.
>>
>>
>>
>>
>>
>> ________________________________
>> From: USRP-users <usrp-users-boun...@lists.ettus.com> on behalf of Ramazan
>> Çetin via USRP-users <usrp-users@lists.ettus.com>
>> Sent: Tuesday, February 19, 2019 7:11 AM
>> To: Jonathon Pendlum; usrp-users@lists.ettus.com
>> Subject: Re: [USRP-users] E310 RFNoC FFT Overrun Issue
>>
>>
>> Hi Jonathon,
>>
>> Thanks you for your suggestions. I have achieved getting 60 MHz spectrum
>> samples to file on ARM processor using;
>>
>> RFNoC: Radio -> RFNoC: FFT -> RFNoC: Vector IIR -> RFNoC: Keep 1 in N ->
>> File Sink
>>
>> It just getting overflows after 4-5 seconds such as "overrun on chan 0". Is
>> this because of RFNoC side or processor side ?
>>
>> Also, Keep 1 in B block works as using packets not samples this is also
>> perfect for me. I will not lose FFT bins.
>>
>> But i can not much understand Vector IIR part. Why is it used and good for
>> FFT outputs? Is it for averaging results ?
>>
>> Thank you for your time. Best regards.
>>
>> Ramazan
>>
>> On 11.02.2019 08:09, Jonathon Pendlum wrote:
>>
>> Hi Ramazan,
>>
>> I would suggest first testing with a signal generated with GNU Radio. For
>> example, use a Fast Noise Source + Low Pass Filter to crudely simulate
>> receiving a wide band signal. See what it looks like without running it
>> through RFNoC. Then replace the RFNoC radio block with those blocks and look
>> at the result.
>>
>> You should also consider using the ZeroMQ blocks to forward data over
>> Ethernet to a host PC to view your data in real time. Look at the gr-ettus
>> example flowgraphs rfnoc_fft_network_usrp (runs on E310) and
>> rfnoc_fft_network_host (runs on host PC).
>>
>> One guess I can make is try increasing the FFT RFNoC block gain. By default,
>> it is set to a very conservative value, so try changing it to 21. That gain
>> value sets the Xilinx's FFT IP core scaling schedule, which you can read
>> about here:
>> https://www.xilinx.com/support/documentation/ip_documentation/xfft/v9_0/pg109-xfft.pdf
>> (see SCALE_SCH on page 15, the core uses Radix-4). You can also try
>> adjusting it with a slider in real time. Note that it may behave a bit odd
>> as it is not a linear mapping due to the scaling schedule format.
>>
>> The overflows are due to either the ARM processors cannot keep up with the
>> processing load or the SD card write speed is too slow. Try increasing N in
>> Keep One in N.
>>
>> Jonathon
>>
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