Re: Combined constellation modulator/Decoder do not seem to work

[Christophe Seguinot]

Hi

When using differential encoding, this should work, but you have to adjust the delay to compare bits. If my memory is cirrect I succeeded one year ago with a delay equal to 58 (not sure).

Will test as soon as possible.

Could you please share a .grc file?

Regards

On 12/03/2021 16:37, George Edwards wrote:

Hello, 

I cannot get the combined Constellation Modulator/Decoder as shown below to work. The figure below is an example from the online Guided Tutorial PSK Demodulation.... I leave out the Equalizer, Costas Loop blocks, the channel was set to pass the signal unimpaired and the Poly Clock Sync was set for Output sps=1. The constellation plot of the output of the Poly Clock Sync is perfect. Now, in the flowgraph below, the signal entering the Constellation Modulator and that leaving the Constellation Decoder are routed into Time Sinks for display. I route these signals into File Sinks so I can print them and compare 1's and 0's. The results show they are not the same. I passed Constellation Rect.Object parameters to both the Constellation Modulator and Decoder, which seems logical to me, but I could be wrong???

Will appreciate any help you can provide because what enters the modulator should be the same as what is leaving the demodulator. 

Regards, 

George