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Amplitude modulation using parallel port

Question asked by ramola on Apr 1, 2015
Latest reply on Apr 1, 2015 by ramola

Hi,

I want to use the AD9910 eval board to modulate the amplitude of a 80MHz signal. I am using the parallel data port for this. I have set the FTW in register 7 corresponding to 80MHz and then I set the destination bits to 00(for amp) and increment the value of the tuning word at the parallel port. I observe no signal when I do this. On the other hand, when I set the destinaton bits to modulate the frequency I can observe the output on my oscilloscope(around 500mVpp). As I understand from the manual of the AD9910 the amplitude modulation works on the carrier signal which is stored in the FTW register (reg 7). Is this not the case? Or what could possibly be wrong, since all I do is change the destination bits. Thanks.

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