R&S FSMR, Operating Manual

Page: 293 / 955

R&S FSMR Analyzer - MEAS
1166.3363.12 4.16-13 E-2
With the exception of the IS95 CDMA standards, the ADJUST SETTINGS
softkey sets the resolution bandwidth (RBW) as a function of the channel
bandwidth:
RBW 1/40 of channel bandwidth.
The maximum possible resolution bandwidth (with respect to the
requirement RBW 1/40) resulting from the available RBW steps (1, 3) is
selected .
Video bandwidth (VBW) For a correct power measurement, the video signal must not be limited in
bandwidth. A restricted bandwidth of the logarithmic video signal would
cause signal averaging and thus result in a too low indication of the power
(-2.51 dB at very low video bandwidths). The video bandwidth should
therefore be selected at least three times the resolution bandwidth.
The ADJUST SETTINGS softkey sets the video bandwidth (VBW) as a
function of the channel bandwidth as follows:
VBW 3 RBW.
The smallest possible VBW with regard to the available step size will be
selected.
Detector The ADJUST SETTINGS softkey selects the RMS detector.
The RMS detector is selected since it correctly indicates the power
irrespective of the characteristics of the signal to be measured. In principle,
the sample detector would be possible as well. Due to the limited number
of trace pixels used to calculate the power in the channel, the sample
detector would yield less stable results. Averaging, which is often
performed to stabilize the measurement results, leads to a too low level
indication and should therefore be avoided. The reduction in the displayed
power depends on the number of averages and the signal characteristics
in the channel to be measured.
Setting the Channel Configuration
MEAS - CP/ACP CONFIG submenu:
CP/ACP
CONFIG
CP/ACP
ABS REL
NO. OF
ADJ CHAN
CHANNEL
SPACING
ACP REF
SETTINGS
CHANNEL
BANDWIDTH
CHAN PWR
/ HZ
ACP LIMIT
CHECK
EDIT
ACP LIMIT
ADJUST
SETTINGS
NO. OF
TX CHAN
POWER
MODE
SELECT
TRACE
The CP/ACP CONFIG softkey opens a submenu
for configuration of the channel power and adjacent
channel power measurement independently of the
offered standards.
The channel configuration includes the number of
channels to be measured, the channel bandwidths
(
CHANNEL BANDWIDTH ), and the channel
spacings ( CHANNEL SPACING ).
Limit values can additionally be specified for the
adjacent-channel power (
ACP LIMIT CHECK and
EDIT ACP LIMITS ) which are checked for
compliance during the measurement.