You don't need to measure it. You need to ask yourself *why* a constellation with many points might not work well with a low SNR.
Then you have your answer. On 11.11.20 14:03, p...@koalatech.pt wrote: > I don know how can I measure the SNR with QAM modulation. There is only > a MPSK SNR probe. > Can you tell me how to measure SNR with MQAM? > > Thanks for your help, > Pedro Viegas > > Citando Marcus Müller <mmuel...@gnuradio.org>: > >> Hi. this is a typical question like I'd ask it when talking a student >> through a test for a digital comms computer lab. So here's a hint: >> >> "Constellations with very many points" don't always work. It has to do >> with SNR. Can you explain what the problem is with low SNR? >> >> Best regards, >> Marcus >> >> On 10.11.20 12:56, p...@koalatech.pt wrote: >>> Hi, I'm trying to make an OFDM transmission of a png file (9.3 kB) with >>> 256QAM with the gnuradio >>> example of OFDM transmitter / receiver. The USRP I'm using is the ettus >>> n210 with the cbx daughter board. With the QPSK and 16QAM modulations it >>> works, but with 64QAM or 256QAM I can´t receive the file, sometimes it >>> receives some packets but most of the time it doesn't receive any byte. >>> Can anyone help me with with this problem? >>> >>> Thanks in advance. >>> Pedro Viegas > >
