Ada, >>once the signal has been up converted. Now I'm using 0.2 amplitude and 35 gain. But I don't understand, how come that the smaller the power is, the better transmission performance there will be. And also, why does power should be in the range of 0 to 1.0? How to calculate transmission power using the -tx-amplitude and tx-gain? Better performance is not due to smaller power but it is due to the non-linear effects of RF-amplifiers. As per my observations, Tx-Dsp amplitude beyond 0.15 to 0.2 causes the USRP daughter-boards Tx-amplification-stage to go into non-linear region thus error-rate of PSK/QAM increases. Non-linear modulation e.g. FSK/GMSK are more robust to Amps non-linear effects. so u can experiment increasing TX-amplitude both for FSK-variants & PSK/QAM and observe performance.
-Adeel On Tue, Jul 23, 2013 at 9:25 PM, yeran <yeran0...@hotmail.com> wrote: > Hi everyone, > > I'm doing a project on joint decode. But my problem is that in the lab > environment, the benchmark transmission is always good, there are hardly > any packet loss, so I can not show the advantage of joint decode. > > I've tried to change the physical distance from transmission to receiver > attenna. Still works really well even put in opposite side of the building. > > I've tried to change the transmission power and transmission rate. > Inspired by some previous study, I learned that transmission power is > controlled by -tx-amplitude and -tx-gain, in which -tx-amplitude sets the > amplitude of the signal going into the DAC. RF gain is applied in the > daughtercard once the signal has been up converted. Now I'm using 0.2 > amplitude and 35 gain. But I don't understand, how come that the smaller > the power is, the better transmission performance there will be. And also, > why does power should be in the range of 0 to 1.0? How to calculate > transmission power using the -tx-amplitude and tx-gain? > > Is there any other way that may cause more error in transmission beside > the ones I mentioned? > > Thanks in advance! Any suggestion will be greatly appreciated! > > Ada > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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