Agilent Technologies E4406A manual measurement data

Making Measurements

Making the Spectrum (Frequency Domain) Measurement

Table 4-1	Spectrum (Frequency Domain) Measurement Defaults
	Measurement Parameter	Factory Default Condition
	Decimation	0; Auto
	IF Flatness	On

NOTE	Parameters under the Advanced key seldom need to be changed. Any
	changes from the default advanced values may result in invalid
	measurement data.
	Make sure the Spectrum (Freq Domain) measurement is selected under
	the Measure menu. Press the Meas Setup key to access a menu which
	allows you to modify the averaging and trigger source for this
	measurement (as described in the “Measurement Setup” section). In
	addition, the following parameters can be modified:
	• Span - Allows you to modify the frequency span. The range is
	10.000 Hz to 10.000 MHz with 1 Hz resolution, depending on the Res
	BW setting. Changing the span causes the resolution bandwidth to
	change automatically, and will affect data acquisition time.
	• Res BW - Allows you to set the resolution bandwidth for the FFT, and
	to toggle its mode between Auto and Man (manual). If set to Auto, the
	resolution bandwidth is set to Span/50 (2% of the span). If set to Man,
	you can enter a value ranging from 100.0 mHz to 3.00000 MHz. A
	narrower bandwidth will result in a longer data acquisition time.
	• Advanced - Allows you to access the menu to change the following
	parameters. The FFT advanced features should be used only if you
	are familiar with their operation. Changes from the default values
	may result in invalid data.
	— Pre-ADC BPF - Allows you to toggle the pre-ADC bandpass filter
	function between On and Off. The pre-ADC bandpass filter is
	useful for rejecting nearby signals, so that sensitivity within the
	span range can be improved by increasing the ADC range gain.
	— Pre-FFT Fltr - Allows you to toggle the pre-FFT filter between Flat
	(flat top) and Gaussian. The pre-FFT filter defaults to a flat top
	filter which has better amplitude accuracy. The Gaussian filter
	has better pulse response.
	— Pre-FFT BW - Allows you to toggle the pre-FFT bandwidth function
	between Auto and Man (manual). The pre-FFT bandwidth filter
	can be set between 1 Hz and 10 MHz. If set to Auto, this pre-FFT
	bandwidth is nominally 50% wider than the span. This
	bandwidth determines the ADC sampling rate.
	— FFT Window - Allows you to access the following selection menu.
	Unless you are familiar with FFT windows, use the flat top filter.

100 Chapter 4