Keysight WLAN Measurement Guide 111
Concepts
WLAN Measurement Concepts
Spectrum Emission Mask Measurement Concepts
Purpose
The Spectrum Emission Mask measurement is used to test the in-band
spurious emissions. It may be expressed as a ratio of power spectral densities
between the carrier and the specified offset frequency band. The power
spectral density of the transmitted signal shall fall within the spectral mask.
Measurement Method
The Spectrum Emission Mask measurement measures spurious signal levels in
up to six pairs of offset frequencies and relates them to the carrier power. PSD
(Power Spectral Density) is used for this measurement. Spectrum Emission
Mask measurement is made with both sides centered at the carrier channel
frequency bandwidth. The specifications require the reference to be the PSD of
the signal. The reference power therefore can be obtained in 100kHz resolution
bandwidth as a reference PSD related to 100kHz. Each offset peak PSD
displayed is either a relative PSD to the peak PSD in the signal or an absolute
PSD.
This measurement requires the user to specify measurement bandwidths of the
carrier channel and each of the offset frequency pairs A to F. Each pair may be
defined with unique measurement bandwidths. Test Limits are also defined in
each offset. The results are displayed as relative PSD to peak reference channel
PSD in dBc, or absolute peak PSD in dBm and minimum margin from limit line
in dB at the minimum margin point. The minimum margin from limit line is the
peak value relative to limit line in each offset.
Figure 3-13
Spectrum Emission Mask Measurement (802.11n)