Re: [Discuss-gnuradio] trouble with QAM mod/ WX GUI Constellation Sink

[Martin Braun]

On 17.07.2015 12:43, Bill Eaton wrote:
> From Martin Braun:
> 
>>My preference is to build the demod/sync chain with it's own blocks, and then 
>>just output the complex symbols 
> 
>> into either an X/Y plot (WX) or the QT Constellation Sink
> 
> Even an X/Y plot ends up looking funny. I’ve attached a GRC file for
> X-Y, and when you turn on persistence, it looks better. But it’s very
> strange. Maybe my bits_per_symbol is wrong. Or maybe the sample rate for
> the X-Y chart should be different than the random sample rate? Here’s
> the 4 QAM X-Y.

Your plot looks fine, it's just oversampled (but perfectly
time-synchronized, I'm guessing this is post-pulse shaping + noise?).

What I meant was that you plot the result of your timing + phase
recovery into an XY plot, that would take care of those additional
points you're seeing.

M