Re: [Discuss-gnuradio] How to repeatedly & continously transmit a signal from a file ?

[Sean Nowlan]

On 06/04/2013 01:09 PM, Monahan-Mitchell, Tim wrote:
> > - How is it possible to transmit a file (as a signal source) repeatedly and 
> > continously without interrupts (with gnuradio & uhd) ??
>   
> > Even without the USRP (i.e. just simulating with throttle & graphical sinks and 
> > a file source) interrupts occurs (time-periods of no samples) for each time the 
> > file repeats (i.e. starts over from the beginning). Same thing with transmitting 
> > with USRP as uhd-source (then without throttling of course), however no underruns 
> > are reported.
> > I want to continuously send a prepared signal from a file over and over again but 
> > can't accept the interrupts each time the file ends & starts over. This happens 
> > even at slow sample rates and I want to transmit really fast!
> > I might have found a solution to this about year ago but now I can't remember 
> > what I did... something simple...
> > Somehow read in the whole file into cached memory so it doesn't need to be 
> > re-read from disk for each repetition (in Linux)... but how?
> Maybe create a small ram-disk outside of GNU Radio, then copy your file to it, 
> then use the new path for the file source block?
Depending how big this file is and how much memory you're willing to 
consume, you can read your file into a vector (from Python, this is 
pretty easy with numpy.fromfile() or a simple for loop ) and use it to 
initialize a vector source (with repeat=True).
> - Tim
>
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