Dear all,

I am getting started with the USRP2 blocks from Matlab 2010b along with the USRP2 basic receiver.

Although the basic Rx cannot be tunned I tried to build a FM demodulator

The simulink setup is: USRP2 Source 256dec- Mixer 100KHz- LPF 75KHz- FM Dem - Resampler 48KHz- Audio sink (file attached)
(This setup tries to demodulate a signal at 99,9 MHz which is band pass sampled at 100KHz due to the 100MHz frequency sample of the ADC)

If I set a decimation less than 512 the 'Lost packets' output reports a lot of dropped packages. Since I have a quite new quad-core laptop I think it should be enough to run this setup. Do I have to set-up some optimum configuration parameters elsewhere in order not to loose packets? By the way, how is the lost packet output triggered? I mean how the block figures out that more data arrived to the UDP buffer and it couldn't be stored. I would like to know the inside of the block (besides the USRP2_RX code that doesn't say a lot).

If I close the FFT scope form the workplace the number of lost packets decreases. Does simulink need a lot of CPU capability? I expected to see it running with different decimation values and the spectrum scope at the same time.

When running my set up at 256 decimation I get more or less 60% of packets which should be fair to identify my FM modulated signal but I only hear noise at the output.

Did anybody tried the same?

Many thanks in advance,
Jorge.