Re: [Discuss-gnuradio] Transmitting data from file using benchmark_tx.py, recieving to file with benchmark_rx?

[Francesco B.]

Perhaps explaining progress thus far would be in order. Currently I'm using
tunnel.py to establish an IP connection between two computers (as it was
intended for), and manipulating said connection by using a unix pipeline and
the scp command in two locations. This works, but doesn't seem the most
efficient method, and also isn't manipulating things on the level of
gnuradio. What I need is a way to establish a gnuradio pipeline that does
that one specific task, rather than manipulating TCP/IP only. I know I can
start with a file source, and then use dbpsk_mod() to modulate the contents
of that file source. And I think sending across the USRP involves importing
benchmark_tx and using the function send_pkt(), specifying the location of
the desired file to transmit as "payload". Connecting benchmark_rx to a file
sink is a much more confusing matter for me, however, since there is no
intuitive "receive_pkt()" function, or place to specify what directory/file
to write all received packets to.

Are there any modules I should be looking into on a lower level than
benchmark_*? Or am I missing something here?

~ Francesco


Francesco B. wrote:
> 
> Hello,
> 
> I am attempting to establish bidirectional communications between two
> computers using USRPs. As a proof of concept, I would like for one
> computer to be transmitting a sequence of numbers (i.e. the complex
> numbers corresponding to a sine wave), and the other to receive this and
> immediately send it back to the transmitting computer. The bidirectional
> link portion is effectively done with tunnel.py, emulating an ethernet
> connection with the TUN/TAP driver. It works fine - each computer can ping
> the other. However, in order to implement it this way I would need to
> write a driver outside of GNU Radio entirely, to make use of the emulated
> ethernet connection gr0. I would prefer to generate a pipeline that
> handles all of this within it, as I've spent the past ~10 weeks
> familiarizing myself with how pipelines are handled. Much of this has been
> dealing with FM transmission rather than using certain digital modulation
> schemes, so some parts are still foreign, but it is less of a jump for me.
> 
> So... this brings me to an alternative, for which I have a concept but am
> still missing a few pieces before implementation is possible.
> 
> On the "smart" transmitting end, I would have a file source containing the
> output of a signal generator (i.e. usrp_siggen.py), followed by passing it
> through benchmark_tx to the receiving computer. The receiving computer
> would have a simpler pipeline connecting the output of benchmark_rx to
> benchmark_tx, passing it back. The original transmitting computer would
> have benchmark_rx running as well, and be storing any output in another
> file.
> 
> Basically, I want to have it go as follows:
> 
> file source --> benchmark_tx <=====> benchmark_rx -->benchmark_tx
>                                                                               
>      
> ||
>                                                                               
>      
> ||
>                                                                               
>      
> \ /
>                                                             file sink  <--
> benchmark_rx
> 
> But... I've yet to see benchmark_tx and benchmark_rx used as elements of a
> pipeline rather than executables unto themselves, and have also yet to see
> benchmark_tx accept a specific file source, or benchmark_rx deliver
> received packets to a file sink. The code for benchmark_tx only appears to
> generate packets from an unspecified source and transmit them, and
> benchmark_rx doesn't specify a destination for what it is recieving. How
> does one specify this? Clearly, there is something I am not grasping in
> the transition from FM to DBPSK.
> 
> 
> 

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