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Chapter 3, Description of Screens
Adjacent Channel Power Screen
How the Test Set Measures Adjacent Channel Power (ACP)
When you access this screen, the Test Set automatically starts a multi-step process
for measuring ACP:
1. AF Generator 1 is turned off if the Carrier Ref field is set to Unmod.
2. The amplitude of the center frequency (Tune Freq) is measured to establish a refer-
ence.
3. AF Generator 1 is turned back on if it was previously turned off.
4. The power in each of the adjacent channels is analyzed.
5. Adjacent Channel Power is calculated and displayed. This value can be displayed as an
absolute power level or as a ratio referenced to the center frequency’s level.
NOTE: Which Input Port to Use. The TX Power measurement is used to calculate absolute Adjacent
Channel Power. Since TX Power can only be measured using the RF IN/OUT port, you must
use this port to measure ACP Level. ACP Ratio can be measured using either the RF IN/OUT
or the ANT IN port.
Measuring ACP on AM Transmitters. When measuring AM signals, the reference level
must be measured on an unmodulated carrier; so the Carrier Ref field must be set to
Unmod. After the reference is measured, the power in the adjacent channels must be measured
with modulation. This requires the modulating signal to be turned off and on repeatedly as
measurements are being calculated and displayed. Since the Test Set automatically turns
AFGen1 on and off when the Carrier Ref field is set to Unmod, you must use AFGen1
and the AUDIO OUT port as the modulation source for making AM ACP measurements.