[Discuss-gnuradio] Simple QAM mod/demod

[Fabián Kozynski]

As sanity check I'm trying a simple flowgraph in GRC with a QAM mod/demod:

Vector Source ==> Throttle ==> QAM Mod ==> QAM Demod ==> Unpacked to Packed ==> File Sink

The parameters in the mod/demod are as default. I also have a File Sink before the mod.

In the output I see first a bunch of zeros, then a bunch of random numbers and after 20 or so bytes I get a sequence with the same period as the original one, but different numbers. I suppose this is a problem of phase sync.

What's the right way to simulate a simple mod/demod? How do I add sync between mod and demod?

Thanks,

Fabián