5660 frequency accuracy

[terrill]

Andy,

I first tried to place the code from your example in my code and it did not work. I decided to run your example as is and I cannot seem to get it to work. I am inputting a 1 MHz signal at 0 dbm and no matter what I set the controls to I cannot see the sine wave on the graph. I can see some knid of wave if I turn on a FM deviation > 30 KHz. I am at a loss here.

Terrill

[Andy_Hinde]

Hi Terrill,
I apologize - I should have explained more thouroughly. You won't see a sine wave on the graph because you are acquiring baseband complex IQ data, not real data. A sine wave is represented by a single IQ pair at baseband. It is the same thing as a magnitude/phase vector (phasor), except IQ data is given in Cartesian (X,Y) points instead of mag/phase (r,theta).
What you are looking at is a plot of power vs time and voltage vs time. The power and voltages are not instantaneous like on a scope. One IQ pair (which the block diagram converts to power and voltage Vp-p) represents the magnitude of the sine wave, not the instantaneous power/voltage.

If you are measuring a modulated signal, you need to make sure the configured bandwidth encompasses the entire signal, which would be 2 * FM deviation. Then the power represents the total power of the signal and the Vp-p doesn't realy apply since the input sinal is not a sine wave.

Thanks,
Andy