Re: [Discuss-gnuradio] help generating frequency offset

[Matt Ettus]

George Nychis wrote:
> Hi all,
>
> I'm attempting to generate frequency offset in a script that is adding 
> some channel features:
>   http://cyprus.cmcl.cs.cmu.edu/matched_filter/gen_noise_samples.py
>
> The frequency offset is specified, for which the original signal is 
> mixed and then the offset signal is added with the noise.
>
> But I'm not seeing the appropriate frequency offset.  If I specify a 
> frequency offset of 100Hz, I'm only seeing a single point shift, all 
> other points are the same as if there is no offset:
>   http://cyprus.cmcl.cs.cmu.edu/matched_filter/graphs/freq_offset.jpg

I'm not sure what you have plotted in that picture.  Is that just the 
raw samples?  Can you write out to a file both the 2 inputs to the mixer 
and the 1 output?  Then do an FFT on all 3 in octave to make sure the 
frequency has really moved as you expected.

Matt