Agilent-technologies VXI E1439 Manual do Utilizador descarregar pdf (Página 37)

Using the Agilent E1439

Delay and phase in triggered measurements

Due to the pretrigger delay of 32, the desired trigger point would have been at the 32nd sample of

the time record. However, the delay_actual value of 16 indicates that the sample corresponding

to the actual trigger is number 32+16/2

or the 33rd sample. The measured phase of the 33rd

(complex) sample, found via the atan2() function, is 159 degrees. The phase of the LO at this

sample is 19697*360/65536=108 degrees. Adding these together to get the corrected phase of the

input signal results in 267 degrees = -93 degrees, which is close to the expected phase of a sine

wave triggered at its zero-crossing, which would be -90 degrees.

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Agilent-technologies VXI E1439 Manual do Utilizador Página 37