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Re: [Discuss-gnuradio] help with QAM demodulation

From: Ben Reynwar
Subject: Re: [Discuss-gnuradio] help with QAM demodulation
Date: Mon, 27 Feb 2012 10:00:26 -0700

On Mon, Feb 27, 2012 at 7:36 AM, Jeff Hodges <address@hidden> wrote:
> Does anyone know if the QAM demodulator code is working properly?  I would
> like to get a QAM demodulator working for a symbol rate of 300ksym/s. I
> don't know whether I am just using the wrong parameters or if the blocks do
> not work properly, but I am not getting the results I expect.
> To test the code out I am using the GRC. I have a vector source with a known
> data sequence running into the qam mod block and then the output of that
> into a QAM demod block. The output of the QAM demod is running into a Uchar
> to Float, and I am plotting the results on a WX GUI Scope.  I have the exact
> same settings on both the QAM mod and demod blocks.  The output I am seeing
> on the scope looks completely random. (I also tried other vector source
> data: When the input is 0x0F, repeating, the output I see is 00001010
> repeating. But when I use 0x0E, the results are random again.)
> I have also tried demodulating a real QAM signal with a known data sequence,
> also to no avail.
> I have been working on this for about a month now and haven't had any
> success.  I have examined the underlying QAM.py and generic_mod,
> generic_demod codes, and they seem to be written properly. But I am not
> getting the expected results.
> Any help with this problem or advice you can give will be greatly
> appreciated, and I will return the favor by helping out in any way that I
> can.
> Thank you very much in advance,
> Jeff
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

If it's not working it's probably my fault, so I'll do some tests
myself today and get back to you.


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