Re: [Discuss-gnuradio] Acoustics instead of radio & what's possible inreal-time?

[Jeff Brower]

Jim-

> I'm working on a software-defined acoustic communications transceiver,
> currently based on DSP-targeted code generated by MATLAB and Simulink.
> I'm looking into options for converting the project to free software and
> so far I have been reading about Scicos and GNURadio. As part of moving
> to a free software platform, I would also transition the system from a
> DSP target to a general purpose (PC) processor.
>
> I'd like to make the whole system real time capable (rather than
> data-acq followed by post-processing) and I hope to get an idea from the
> gnuradio list membership of what is possible on a general purpose
> processor, and whether GNURadio is a good platform choice for my
> application. For example, one difference from more typical SDR projects
> is that we are doing direct quadrature sampling without a HW basebanding
> front end. In the current design, the receiver does:
>
> - sampling at 4x the carrier (Fc @ 12kHz now, may go up -> 48ksps min,
> maybe 96ksps in the future?)
> - digital I-Q demodulation, decimation
> - correlation to detect start-of-packet
> - demodulate & decode packet of QPSK symbols (training & data bits)
> using a digital PLL, decision feedback equalizer and viterbi decoder,
> currently 200 training symbols & 600 data symbols
> - a bit of MAC and application layer stuff (but this is lower processor
> demand)
>
> Is this possible? Or perhaps trivial, compared to RF data rates? Does it
> look like I'd need to write a bunch of new blocks if I moved to GNU
> Radio? :)
>
> For comparison, the existing (floating-point) DSP implementation runs a
> bit behind real time. It takes about 3 seconds to process a packet of
> length ~0.7 second.

How many MFLOPS does your DSP solution currently require?  You mention a 
floating-point DSP; is it the Texas Inst
C6713?  If so is it running 300 MHz / 1200 MFLOPS?

-Jeff


 I would like to do better. The PC-compatible
> hardware platform I had in mind is the Via PX10000 (for size/power
> reasons); it seems fairly fast and has a nice built in audio codec with
> a high sampling rate.
>
> http://www.engadget.com/2007/06/03/via-epia-px10000-pico-itx-motherboard-gets-reviewed/
>
> I am fairly new to software-defined radio in general. Thanks in advance
> for any suggestions.
>
> --Jim Morash
> address@hidden