Installation Instructions

 
Measure and record phase/amplitude for upper antenna transfer signals. Then determine if
one of the monitor cables must be trimmed in order to comply with phase tolerance for the set
of cables.
Tolerance: ±1°.
Amplitude tolerance: ±1.0 dB. If the amplitude tolerance is exceeded something might be
wrong in the Antenna monitor circuit or connector/cable.
Record final result in Ground Commissioning Records.
8.2.4 Antenna return loss
Utilise a vector voltmeter or network analyser in a test set-up Figure 8-3. Measure return loss
for each Antenna.
Measure and record in Ground Commissioning Record the return loss value for each Antenna
including antenna cable.
Tolerance: 20 dB minimum
.
Figure 8-3 Antenna return loss measurement set-up.
8.3 CSB/SBO Phasing
8.3.1 CSB and SBO cables
The CSB and SBO cable between NM3531 cabinet and MCU must be of equal electrical
length. Utilise a vector voltmeter or network analyser in a test set-up as in Figure 8-1.
Measure open cable return phase for each cable.
Refer to CSB cable as zero phase and measure the return phase for the SBO cable. The
cable pair must be matched within ±3.0° return phase, equal to ±1.5° true phase.
8.3.2 CSB/SBO phasing
Insert the 90°-stub in the SBO cable path to the ADU. Connect the NM3710 Field Test Set to
20dB
AB
VECTOR VOLTMETER
From cabinet
CSB BNC o/
p
DIR. COUPL.
Antenna cable under test
Antenna