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3 Spectrum Analyzer Mode

3.2 Swept SA Measurement

instruments are capable of making Quasi Peak and EMI Average detected

measurements correctly on a log scale, due to the digital IF. This latter capability

means that the user can observe detected EMI levels on a log scale, allowing a large

visible dynamic range. You can manually set the Average Type to Log-Power or

Power, but the results will no longer be CISPR compliant.

Also, in the past, EMI analysis equipment would need to perform a ranging

operation to set the reference level when one of these detectors was turned on, but

the X-series instruments do not - because of its digital IF, there is no need to set the

reference level (range) to improve the accuracy nor to allow visibility of the detected

level.

EMI Average

The EMI Average detector in Agilent’s X-Series instruments is so called to

distinguish it from the Average detector, although EMI users typically refer to it

simply as the “Average detector”. The intent of this detector is to provide a standard

means to “smooth” the signal while still providing compliance to CISPR pulse

response standards.

Unlike the regular Average detector, which averages on a bucket-by-bucket basis

using either a power, log-power or voltage scale (a bucket is the same as a trace

point), the EMI Average detector displays the average value, on the voltage scale, of

the overall amplitude envelope, independent of the trace bucket width. It is defined

for EMI measurements by the CISPR 16–1–1 standard and, in the X-series, uses a

sophisticated algorithm to implement a lowpass filter that conforms to the latest

CISPR standard.

Note that CISPR standard operation is to perform the envelope averaging on the

voltage scale. You can manually set the Average Type to Log-Power or Power, but

the results will no longer be CISPR compliant. See note under Quasi-Peak.

RMS Average

Not to be confused with the RMS mode of the regular Average detector, this is a

special filter for making EMI measurements. It is a frequency dependent

RMS/Averaging filter, used in making CISPR compliant EMI measurements. This

filter conforms to the 2007 revision of the CISPR 16–1–1 standard. This detector

does one averaging process (in the VBW hardware) on the "power" (a.k.a. RMS)

scale and another process on the voltage scale using a "meter movement simulator"

similar to the one used in the QPD filter.

Note that CISPR standard operation is to perform the envelope averaging on the

voltage scale. You can manually set the Average Type to Log-Power or Power, but

the results will no longer be CISPR compliant. See note under Quasi-Peak.

Spectrum Analyzer Mode User's &Programmer's Reference 527

Keysight x-series User Manual

Other manuals for Keysight x-series