[USRP-users] Extending 'tx_sample_from_file ' to send multiple files over multiple TX

Ali Dormiani sdormian at eng.ucsd.edu
Wed Feb 6 19:39:52 EST 2019


I just realized that even one instance of TX_sample_from_file from the
internal Linux is a no go.

In fact I think I was in a thread about this very subject a few months ago.
Someone explicitly said the ARM cpu would be too weak to stream samples.

Even streaming one file at the lowest possible sampling rate got 100%

I'm trying to avoid gnuradio for this situation because that would require
borrowing a bunch of laptops and finding some Ethernet to USB adapters.

I guess that is the best option as my FPGA knowledge is too limited to go
down the custom RFNoC route.

Thanks for the help.

On Wed, Feb 6, 2019 at 3:12 PM Rob Kossler <rkossler at nd.edu> wrote:

> Hi Ali,
> A few comments...
> 1) perhaps use gnuradio and attach four file source blocks to the usrp.
> This is probably the easiest.
> 2) perhaps modify the tx_samples_from_file as you suggested.  If you want
> to go this route, I may be able to dig up some old code where we did this.
> 3) In either case above, is there a bandwidth limitation from the N310 CPU
> to the FPGA that may make these unsuitable?
> 4) perhaps use custom RFNoC image with the 'replay' block.  This would
> work great if you don't have to control the channel-to-channel relative
> timing (the replay block doesn't support).  But, the drawback is you would
> have to be able to compile such an image and you would likely want to use
> gnuradio/gr-ettus to run on the CPU because it is non-trivial to control a
> custom RFNoC image from UHD.
> Rob
> On Wed, Feb 6, 2019 at 5:15 PM Ali Dormiani via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>> Hello everyone,
>> I'm trying to set up a few N310's in neighboring buildings. I want each
>> N310 to be its own 4 TX transmitter.
>> For space and cost reasons I am putting the waveforms (in binary float32)
>> directly on the SD card filesystem. My goal is to have each N310 send the
>> waveform on loop indefinitely.
>> So I have 4 .bin files that I want to transmit, one per TX.
>> I'm not proficient in c++ but the provided tx_sample_from_file seems to
>> only work with one file-antenna pair.
>> Could I make a script that runs 4 duplicate commands with different
>> arguments? I suspect the MPM claiming system would not like this though.
>> Otherwise, is modifying the the example c++ (add more file and antenna
>> arguments) the best path forward?
>> Thank you all for your time,
>> Ali
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