Re: [Discuss-gnuradio] On air 16_QAM transmission problem with USRP N210

[Martin Braun]

On 29.04.2014 23:22, zielalaoui wrote:
> Hi all,
> I am trying to build transmission on air by using USRPs N210. The
> transmission is good with MPSK modulations but when i try to use 16_QAM i
> could not receive data (0 bytes at the reception). I tried to adapte
> transmission power, gain at the tranmitter, gain at receiver, samp_rate but
> the reception file still always empty. This is my flow graph:
> Tx: file source => packet encoder => QAM mod => mult constant = 0.4 => UHD
> usrp sink
> Rx : UHD usrp source => QAM demod => packet decoder => file sink
> samp_rate= 2M
> samples/symbol = 8
> centre frequency=2.4G
> Any proposition will be appreciate
> Thanks to all

There are lots of things that can go wrong. At 16-QAM, you'll likely 
have some bit error, and you have no FEC to compensate for that.

Martin