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Altera_Forum's avatar
Altera_Forum
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17 years ago

NCO 8.1 Problem

HI, no matter what output freq. I set my NCO to have it is always coming out at 20 Mhz, or this is what I am measuring on the scope. I don't think this was happening when i was using quartus 6....
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

Hi,

I will assume the Fs of your NCO and DAC are fixed.

In that case you can confirm the problem through signaltap by directly checking the tuning word value at the NCO.

You may even take samples of sine data and meaure the frequency in Matlab by setting signaltap to signed values then convert to text file(remove header and you are left with table that can be read).

Kaz