[Discuss-gnuradio] DPSK block problem

[Songsong Gee]

I want to send an receive data with DPSK modulation

So I made a simple testing GRC graph

https://picasaweb.google.com/lh/photo/wYSKGiQz-0xB5EXtfEe_HQ?feat=directlink

Originally, I separated TX part and RX part, TX part performs DBPSK mod and passes to USRP sink

and RX part USRP source gives a signal and performs DBPSK demod and plot it

Currently I put them together into one grc graph, but the result are all same

So you just can understand it's no problem

The real problem is the received signal is not what I expected.

Here is the received signal waveform.

https://picasaweb.google.com/lh/photo/63zs3JdmyAS-oMCyyh17Ug?feat=directlink

The bottom is the modulated signal, and the upper is the demodulated signal

BUT what I expected after demodulation is like below:

https://picasaweb.google.com/lh/photo/H9RItzjpfemHy-OR2eQhQg?feat=directlink

And this is same as the original source.

(Except the magnitude, after demodulation I want rectangular pulse with magnitude 1)

Might be, It seems I don't understand parameters of DPSK (de)mod blocks

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