Tektronix CMD 80 User Manual page 265

TDMA: Manual Test
3–196
ADJ CH PWR FREQ DOMAIN. The adjacent channel power measurement allows
the user to measure the adjacent, first, and second alternate channel power and
display the results in a frequency domain view. See Figure 3–155.
These are the three neighboring channels above and below the current active
channel. This measurement is made at frequency offsets of
channels), 60 kHz (alternate channels), and
channels). The tester uses a passband filter (described in IS-136-A section
2.1.3.3) to eliminate interference from unwanted sources.
There are two different effects to be covered by this measurement. First, the
power that is part of the mean power output of the transmitter resulting from the
modulation and noise. This refers to the calculated RMS values. Second, the
out-of-band power arising from the switching transients (caused by the ramping-
on and ramping-off of the transmitter) is covered by the calculated Peak values.
The RMS measurement is made using 50% of the symbol periods in one time
slot of the active channel. Only 50% of the the symbols are evaluated to increase
measurement speed. The measurement results are statistically evaluated; for each
channel the absolute peak, the maximum, and the average RMS value is
calculated over a user defined number of bursts. The measurement results are
presented either in absolute values (dBm) or in relative values (dBc). In the latter
case the RMS values are relative to the RMS power of the active channel (due to
modulation). The PEAK values are relative to the PEAK power of the active
channel (due to switching). The RMS and PEAK power of the active channel are
averaged over a user defined number of bursts.
The results are presented graphically as bars, using either RMS, peak, or
common (both RMS and peak) DISPLAY MODE, over a variable number of
bursts (1 to 1000). The MS sync number detected, RF channel, and the bursts out
of range are also displayed.
CMD 80 Digital Radiocommunication Tester User Manual
30 kHz (adjacent
90 kHz (second alternate