Re: [Discuss-gnuradio] What Modulation Scheme does RFX400 can perform?

[Nick Foster]

On Wed, 2011-01-12 at 01:57 +0900, Songsong Gee wrote:
> Same as Title, What Modulation Scheme does RFX400 can perfom?
> 
> 
> If I draw a flow graph like below:
> http://dl.dropbox.com/u/11382666/02_RXTX/TX.grc.png
> 
> 
> What Modulation Scheme is used by default?
> 
> 
> Can I change it?

Songsong,

The modulation can be anything you want it to be. It's a little
confusing if you aren't used to thinking about DSP and SDR. The USRP+RFX
will happily output the raw samples you put into it, and it's up to you
to encode them with a reasonable modulation. The same works for receive.
If you FM modulate your data, it will be FM modulated when it goes out
on the air. If you AM modulate it, it will be AM modulated. 

For another example, the process to AM demodulate a signal is just a
complex-to-magnitude transform (i.e., y=|x|). So you can use
gr.complex_to_mag as an AM demodulator. There are existing blocks to do
FM demodulation as well. They can be found in gnuradio-companion under
"Modulators". Any other modulation scheme you can come up with can be
used as well, if you can mathematically describe it and code it up.

Take a look at the examples in gnuradio/gnuradio-examples/python/usrp
for an idea as to what I'm talking about. The AM and FM receivers are a
good place to begin.

--n

> 
> 
> -- 
> Seokseong Jeon (aka Songsong Gee)
> 
> 
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