Forum: GNU Radio OOK Modulation

Hello,

I am working on creating a OOK Modulation block. I have created a block
using the bpsk.py file as an example. I changed the constellation points
such that 1+0j and 0+0j. I am now trying to change the waveform that is
outputted from the USRP. I would like to transmit a square wave for 1 
and
nothing for 0. I am not sure how I can do these. I would greatly 
appreciate
any help or advise that any one could give me. Thank you for your time 
and
help.



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On Fri, Oct 12, 2012 at 5:43 PM, sibar002 <sibar002@ucr.edu> wrote:
> Hello,
>
> I am working on creating a OOK Modulation block. I have created a block
> using the bpsk.py file as an example. I changed the constellation points
> such that 1+0j and 0+0j. I am now trying to change the waveform that is
> outputted from the USRP. I would like to transmit a square wave for 1 and
> nothing for 0. I am not sure how I can do these. I would greatly appreciate
> any help or advise that any one could give me. Thank you for your time and
> help.

What are you seeing when you change the bpsk.py file for your new
constellation? That should be close. The bpsk modulator uses a root
raised cosine pulse shaping filter, is that what your problem is? If
you really want to transmit a square wave (but remember, doing that is
going to throw a lot of signal into the spectrum; also your
transmitter, receiver, and channel are all going to filter this signal
in their own way to distort it), you can change this to a LPF filter
with a wide enough passband to pass the square wave. The filter also
interpolates the signal, which you'll want to do, too.

Tom