[Discuss-gnuradio] Re: Freq in real world vs. Freq in the SW

[Milo Wong]

Oh, There was a typo in my previous description:  The sub-carrier freq I 
set in SW is 4MHz not 2MHz

(i.e. 4MHz sub-carrier set in SW results in a 50KHz sub-carrier on 
FFT.). Please let me know if you have any comments. Thank you.


Milo



Milo Wong wrote:
> Hi folks,
>
> I wrote a amplitude modulation block and here's an interesting problem:
>
> It seemed that the Freq showed on the  plot of post modulation FFT is 
> always (1/80) of the freq I set in the SW.  For example, If I set the 
> sub-carrier freq to 2MHz, and use a message signal (constant 1.0)to 
> modulate that, I can only get a 50KHz sub-carrier showed on FFT plot. 
> I've attached my plots(both in freq and time domain).
>
> Below are the test results:
> freq. in post-mod FFT       freq. set in SW
>     12.5k                             1M
>      25k                               2M
>      50k                               4M
>
> Is there anyone who has some ideas or comments? Thank you!
>
> Milo
>
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