> What is alias filtering ? I have hear about anti-alias filters. > Apologies as I am a CS student > but interested in radios and hence working on the project. I might be > missing something > obvious.
It's the same. As mentioned, your hardware shouldn't be working at 2kS/s at all -- you should definitely read the full textual output of your program > You mean at 400k center freq, I have a sample_rate of 400k X 10 = 4M ? > Isn't this going to increase my transmisson BW ? > No, that's not oversampling. Oversampling is taking your signal as it is now, i.e. calculated for a digital-to-analog conversion rate of 2kSamples per second, and padding it with N-1 zeros after each sample, so that you have N*2kS/s afterwards. Because that N-1 introduces aliases, you have to filter the result, so that the N*2kHz of Nyquist bandwidth actually only /contain/ signal in the central 2kHz. The result is the same signal, just at a higher sampling rate. Best regards, Marcus On 10/21/2015 08:42 PM, abhinav narain wrote: > Hi Sylvain, > > > > You can see the spectrogram at the receiver. I want to do > narrowband(1 kHz) > > transmission hence I am keeping the sampling freq at transmitter > at 1k. > > That sentence is just wrong. It's actually quite the opposite. > > By keeping the sample rate at the transmitter at 1k, you're basically > leaving all the alias filtering to the hardware and it's just not that > good. > > > What is alias filtering ? I have hear about anti-alias filters. > Apologies as I am a CS student > but interested in radios and hence working on the project. I might be > missing something > obvious. > > > You would be much better off oversampling the TX by like 10 and then > do digital filtering to make sure you filter out anything in the > higher freq. > > You mean at 400k center freq, I have a sample_rate of 400k X 10 = 4M ? > Isn't this going to increase my transmisson BW ? > > Sure, I can do that with low pass filter at the receiver, but I don't > want a massive frequency > spectrum signature on the channel itself. My priority/requirement is > to keep my transmission detectability > in the spectrum as low as possible. > > Looking for your comments, > Abhinav > > > Cheers, > > Sylvain > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] <mailto:[email protected]> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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