Tuesday, December 3, 2013

Re: [Discuss-gnuradio] About DPSK mod and demod

Can you try using the PSK mod/demod blocks with differential=Yes instead of the DPSK mod/demod blocks? I found an issue today with the DPSK mod/demod blocks which results in them not actually using differential encoding.

--n


On Tue, Dec 3, 2013 at 9:00 PM, Henry Jin <henry.jin16@gmail.com> wrote:
Hi, 

I tried to build a simple flow graph of DPSK modulation and demodulation. The result is verified using the Error Rate module. The link shows the flow I'm using.

https://www.dropbox.com/s/jwmmttyi4es4alf/Screenshot%20from%202013-12-03%2021%3A50%3A58.png

I know that the output of demod module is unpacked bytes, so an "unpacked to packed" module is attached after demodulation. However, the BER is close to 50%, which surely indicates something wrong. I further analyzed the two inputs of the Error Rate module by writing info to the file sink. It clearly shows the discrepancy. So I just wonder what is wrong with this flow graph. Could someone please help me?

Also, as I noticed, in the output file generated after "unpacked to packed" module, there are many consecutive 0s at the start of the file. Does that indicate something?

Suggestions are greatly appreciated!

Henry

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