System Overview
R&S
®
CMW500
74
User Manual 1173.9463.02 ─ 02
The off-carrier power can be assessed by several complementary quantities:
●
The Adjacent Channel Leakage power Ratio (
ACLR
) is the ratio of the power mea-
sured in an adjacent channel (Adjacent Channel Power,
ACP
) to the transmitted car-
rier power, expressed in dB.
●
In GSM networks, the "ACP Modulation" is measured on a portion of the useful part
of the burst, excluding the power ramps and the training sequence. The result is a
measure for the part of the spectrum that is due to the modulation of the GSM signal.
In contrast, the "ACP switching" result is the peak power within a minimum number
of bursts. This result assesses the switching transients, i.e. the part of the spectrum
that is due to the power ramp-up and down of the signal.
Sign conventions
According to the definition above, the sign of the ACLR values is usually negative. This
is in line with the ACLR definition for networks like GSM and TDMA but differs from the
sign convention for WCDMA (3GPP/FDD); see specification 3GPP TS 34.121. To make
results comparable, the R&S CMW500 uses the GSM sign convention for all network
standards.
Spectrum Emission Mask
The "Spectrum Emission Mask" is a template to limit the out-of-band emissions in a fre-
quency range around the center carrier frequency. Spectrum emission mask conform-
ance tests are specified e.g. for CDMA standards. The spectrum emission mask com-
plements the requirements for the
Adjacent Channel Power (Spectrum)
.
In the figure below, the red lines represent the spectrum emission mask for UL WCDMA
signals (3GPP/FDD 3.84 MHz). The emission mask comprises different sections. In
addition to the limit lines the standard specifies IF filter settings for each section.
Fig. 4-4: Spectrum emission mask (WCDMA/FDD 3.84 MHz)
Measurements
