On Sun, Dec 09, 2007 at 07:16:45PM -0500, Jim Morash wrote: > Hi, > > 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. 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 > [EMAIL PROTECTED]
Jim, GNU Radio should be a good fit for your problem. Most PC's have got plenty of FLOPS to run your problem in real time. We routinely deal with signals up to 8MS/s complex, though of course it depends on what you're trying to do. You may need to write a few blocks, but I think you'll find that most of them already exist. If you build the documentation (./configure --enable-doxygen) and point your browser at gnuradio-core/doc/html/index.html you'll find a list of blocks under "Classes" / "Class Hierarchy". This doesn't include the hierarchical blocks implemented in python. You'll find those by looking in gnuradio-core/src/python/gnuradio/blks2impl If you need more pointers, just ask. Eric _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
