Re: Ofdm transceiver with more than 16QAM

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 <mmueller@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, pv@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


--
Pedro Viegas
Signal Processing Engineer
Koala Tech
phone: +351 917 354 070
e-mail: pv@koalatech.pt