Re: [Discuss-gnuradio] Noisy constellation Output

[Tom Rondeau]

On Thu, Aug 21, 2014 at 11:11 AM, PEEL Luke <address@hidden> wrote:

Hi,

 

I am new to GNU Radio but have noticed something... When I create a PSK modulated signal and output that to a constellation sink, why is the signal so noisy? Why is the signal not in four perfect constellation points?

 

Signal Source -> PSK Mod -> Constellation Sink

 

Thanks,

Luke

That's ISI (inter-symbol interference) due to the transmit pulse shaping filter. The last of our new tutorials (still in beta) covers these issues:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_PSK_Demodulation

Tom