On Wed, Apr 30, 2014 at 3:22 AM, Martin Braun <martin.br...@ettus.com>wrote:
> 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 Also synchronization. That QAM Demod you have right after the USRP source block in your email suggests you aren't doing proper timing, freq, and phase recovery. Tom
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