[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss-gnuradio] help with QAM demodulation

From: Jeff Hodges
Subject: [Discuss-gnuradio] help with QAM demodulation
Date: Mon, 27 Feb 2012 09:36:58 -0500

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,


reply via email to

[Prev in Thread] Current Thread [Next in Thread]