Agilent Technologies N6700 manual Specify a Window Function, Acquisition trigger, use

Operating the Power System 4

4096 DATA POINTS OFFSET = -4095

4096 DATA POINTS OFFSET = -2048

4096 DATA POINTS

OFFSET = 0

OFFSET = 0 to 2 9 4096 DATA POINTS

TIME

	TRIGGER
	To offset the beginning of the acquisition buffer relative to the
	acquisition trigger, use:
	Front Panel:	SCPI Command:
	Select Measure\Sweep.	To offset the measurement on
	Enter an offset value and press	channel 1 by 100 points use:
	Select.	SENS:SWE:OFFS:POIN 100,(@1)
	With a negative offset, values at the beginning of the buffer represent
	samples taken prior to the trigger. When the value is 0, all values are
	taken after the trigger. Values greater than 0 can be used to program
	a delay time from the receipt of the trigger until the values entered
	into the buffer are valid. (Delay time = offset x sample period).
	If, during a pre-trigger data acquisition, a trigger occurs before the pre-trigger
NOTE
	data count is completed, the measurement system ignores this trigger. This will

prevent the completion of the measurement if another trigger is not generated.

Specify a Window Function

Windowing is a signal conditioning process that reduces the error in average measurements made in the presence of periodic signals and noise. Two window functions are available: Rectangular and Hanning. At power-on, the measurement window is Rectangular.

The Rectangular window calculates average measurements without any signal conditioning. However, in the presence of periodic signals such AC line ripple, a Rectangular window can introduce errors when calculating average measurements. This can occur when a non- integral number of cycles of data has been acquired due to the last partial cycle of acquired data.

One way of dealing with AC line ripple is to use a Hanning window. The Hanning window applies a cos4 weighting function to the data when calculating average measurements. This attenuates the AC noise in the measurement window. The best attenuation is achieved when at least three or more waveform cycles are in the measurement.

Series N6700 User’s Guide 71