Bird Technologies VPM3 - Manual (Page 36)

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CCDF measurements are most useful for pseudo-random signals, such as
WCDMA, where a high CCDF means that the transmitter is being overdriven.
CCDF can also detect amplitude distortion within an envelope caused by
unwanted modulating signals. In TDMA systems, CCDF indicates the health of
power amplifier stages and their ability to sustain rated power over an appropri-
ate timeframe. As a trouble-shooting aid, CCDF allows tracking of trends such as
amplifier overdrive (which can cause dropped calls and high bit error rates).
Figure 25 CCDF, 100 W Signal, 80 W Threshold, 20% CCDF
Units
When the Units menu key is pressed, the soft key functions that select the units
of measure are enabled. For power measurements, Watts or dBm can be
selected. For match measurements, VSWR, dB, rho, and percent (%) can be
selected.
Figure 26 VPM, Units, WPS