Re: [Discuss-gnuradio] OFDM RX Script Recovery After Interference

[Martin Braun]

On 04/21/2014 09:02 PM, Jonathan Fox wrote:
> Hey list, another OFDM question.
> 
> I have this simple OFDM script I have used before and in between USRPs I
> have VHF handheld radio I am using as an interferer (also have plenty of
> attenuation, between USRPs it is about 30 dB and the handset is
> attenuated by 55 dB). So with interefering signal around -23 dBm in
> between the the transmission 80 kHz channel which is at -32 dbm as
> according to my handheld Spectrum Analyzer, GNU Radio's FFT plot on the
> RX side gives a transmission of -90 dB and an interference at -50 dB.
> 
> Whenever the handheld goes off, the receiver predictably loses the
> transmitted message and freezes up or the scope goes blank. Depending on
> the duration of the interference of the handheld (just a simple click of
> the tx) usually causes the receiver to lock up and not receive/never
> recover transmitted comms again.
> 
> So why does the RX never recover and how can this be mitigated? I am
> still learning OFDM so I am thinking this is related to the channel
> estimator, is my line of thinking correct?

The channel estimator holds no state, so I doubt that's the problem. Are
you working off of master?

Martin