Re: [Discuss-gnuradio] On Off Keying

[Johnathan Corgan]

On Mon, Sep 29, 2008 at 11:52 AM, sri ram <address@hidden> wrote:

> 3. However, for a tx. stream of 1's and 0's mixed, I still see the received
> amplitude (real part) showing the beat frequency continuously and not going
> to 0 for the 0 bits.

When you send alternating 1's and 0's, you are creating a baseband
square wave of constant power.  The DC offset is half your baseband
transmit amplitude, and that energy at DC is upconverted to your
carrier frequency.  On receive, since you have a frequency offset, you
will see a continuous beat frequency resulting from this constant
carrier. Superimposed on this will be the harmonics of your square
wave up to the Nyquist limit of your baseband sampling rate, or up to
the cutoff frequency of the RRC filter if it is in use.

You could of course change your baseband to be bipolar (-1, 1), but
then again, that's just BPSK.

-- 
Johnathan Corgan
Corgan Enterprises LLC
http://corganenterprises.com/