R&S 1129.7246.03, Operating Manual

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Operating Manual 1302.6163.12 - 03 4.175
R&S ESU Instrument Functions
Analyzer Mode
4.8.13.2 Channel and Adjacent-Channel Power Measurements
For all channel and adjacent-channel power measurements a specified channel
configuration is assumed which is for instance based on a specific radio communi-
cation system.
This configuration is defined by the nominal channel frequency (= center frequency
of the R&S ESU if only one carrier is active), the channel bandwidth, the channel
spacing, the adjacent-channel bandwidth and the adjacent-channel spacing. The
R&S ESU is able to simultaneously measure the power in up to four transmission
channels and up to three adjacent channels (10 channels: 4 transmission channels,
3 lower and 3 upper adjacent channels).
It offers two methods for channel and adjacent-channel power measurement:
• The integrated bandwidth method (IBW method), i.e. the integration of trace pixels
within the bandwidth of the channel to be measured to the total power of the
channel,
• The measurement in time domain (Fast ACP) by means of steep resolution filters
simulating the channel.
The two measurements yield the same results. The measurement in time domain
can be performed much faster since the complete signal is measured within a chan-
nel at the same time. With the IBW method, the channel is divided into subspectra.
This is done by means of a bandwidth which is small compared to the channel band-
width. These subspectra are then combined by integration of the trace pixels.
With the IBW method, the transmission channels or adjacent channels are marked
by vertical lines at a distance of half the channel bandwidth to the left and to the right
of the corresponding channel center frequency (see
Fig. 4.9 ).
With the time-domain method, the power versus time is shown for each channel.
The boundaries of the channels are marked by vertical lines (see
Fig. 4.10 ).
For both methods, the results are listed in tables in the lower half of the screen.
The R&S ESU offers predefined standard settings which can be selected from a
table for the common mobile radio standards. Thus, channel configuration is per-
formed automatically without the need to enter the corresponding parameters manu-
ally.
[ TIME DOM POWER ] Select power measurement in the time domain.
The R&S ESU calculates the mean power from
the points of the whole trace.
The submenu for configuration of the power
measurement is opened.
MEAN is already
switched on.
[ LIMITS ON ] Activate the limitation of the time domain of the
power measurement.
[ START LIMIT : 250 µs ] Set the start of the power measurement at 250
µs.
[ STOP LIMIT : 500 µs ] Set the end of the power measurement at 500
µs.
The GSM specifications require the power to be measured between 50% and 90%
of the TDMA burst. The time limits set above approximately correspond to the
required time domain.