Spectrum Emission Mask Measurement Concepts - Keysight X Series Measurement Manual

Concepts
MSR Measurement Concepts

Spectrum Emission Mask Measurement Concepts

Purpose
Spectrum Emission Mask measurements include the in-band and out-of-band
spurious emissions. It is the power contained in a specified frequency
bandwidth at certain offsets relative to the total carrier power. It may also be
expressed as a ratio of power spectral densities between the carrier and the
specified offset frequency band.
As a composite measurement of out-of-channel emissions, the spectrum
emission mask measurement combines both in-band and out-of-band
specifications to provide useful figures-of-merit for spectral regrowth and
emissions produced by components and circuit blocks without the rigor of
performing a full spectrum emissions mask measurement.
Measurement Method
The spectrum emission mask measurement measures spurious signal levels in
up to 12 pairs of offset/region frequencies and relates them to the carrier
power. The reference channel integration bandwidth method is used to
measure the carrier channel power and offset/region powers. When "Offset" is
selected, spectrum emission mask measurements are made, relative to the
carrier channel frequency bandwidth. When "Region" is selected, spurious
emission absolute measurements are made, set by specifying start and stop RF
frequencies.
The channel integration bandwidth is analyzed using the user defined
resolution bandwidth (RBW), which is much narrower than the channel
bandwidth. The measurement computes an average power of the channel or
offset/region over a specified number of data acquisitions, automatically
compensating for resolution bandwidth and noise bandwidth. The predefined
carrier integ BW and Method are defined in "Carrier Power Measurement
Bandwidth and Filter" on page 67.
Intermodulation test is supported in this measurement. The intermodulation
interference frequency range specified by the parameters under the Intermod
menu is excluded from the measurement when interference power present is
on. The measured points in the excluded region are set to negative infinity.
In the MSR, frequency below OB Start Freq - 10 MHz and above OB Stop Freq
+ 10 MHz is excluded from the measurement frequency range even when offset
ranges include it unless Operating Band is None.
Carrier powers are measured only for carriers specified by Power Ref. When
max power carrier is selected, all carriers with Measure Carrier on are
measured to determine the max power. For example, when Left & Right
Carriers is selected, only the edge carriers are measured and displayed.
60 Keysight N9083A & W9083A Measurement Guide