CMU-Z6
Operating Instructions
1150.0199.12
3
E-3
Improvement of Wideband Modulation Analysis
CMU-Z6 is a hardware option designed to improve the accuracy of the CMU's wideband modulation
analysis. This is achieved by calculating a correction filter from a specific test signal that is applied to the
RF analyzer of the instrument. The correction method is appropriate for modulation measurements on
both 3.84 Mcps QPSK modulated signals and WCDMA (3GPP standard uplink) signals. After correction,
the error of the measured RMS Error Vector Magnitude (EVM) is typically 1.2 %.
Description of CMU-Z6
CMU-Z6 is equipped with two BNC connectors for the input and output of RF test signals, a Sub-D
connector for DC power supply, a selection key and three LEDs indicating the operating mode:
REF IN
RF OUT
DC Supply
Rohde&Schwarz
CMU-Z6 1150.0001.02
0 1 A
1 0 B
1 1 C
MODE SETTING
ON
Input for 110.8 MHz
reference frequency
DC power supply
Output for
test signal
LEDs indicating the
operating mode
Selection key for the
operating mode
Pilot LED
CMU-Z6 is supplied with 3 cables for connection to the CMU200 (see below).
Important Note:
The MODE SETTING key is used to select the operating mode of the CMU-Z6. Mode B must
be selected to perform a modulation correction. The other modes are intended for further
extensions.
Prerequisites for using CMU-Z6
To make use of the improved modulation analysis, the CMU must be able to measure wideband
QPSK or WCDMA signals. This requires that:
•
Software option CMU-K65 or CMU-K0 (for demo units only) is enabled.
•
Hardware option CMU-U65 is installed.
With this instrument configuration, the modulation correction can be performed according to the
description in the next section. No additional software installation is required.