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

[Milo Wong]

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