NORMARC NM 7000 Series, Инструкция по установке и пусконаладке

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Then determine if one of the monitor cables must be trimmed in order to comply with phase
tolerance for the set of cables.
Tolerance: ±2°.
Amplitude tolerance: ±1.0 dB. If the amplitude tolerance is exceeded something might be
wrong in the LPDA monitor circuit or connector/cable.
Record the final result in Ground Commissioning Record.
4.2.6 Antenna return loss
Utilise a vector voltmeter or network analyser in a test set-up Figure 4.3. Measure return loss
for each LPDA.
Measure and record in Ground Commissioning Record the return loss value for each LPDA
including antenna cable.
Tolerance: 20 dB minimum
.
Figure 4-3 Antenna return loss measurement set-up.
4.3 Course sector width adjustments
The required course sector width (CS) can be pre-adjusted by two methods:
1. DDM measurement of ADU antenna feed outputs.
2. DDM field check.
Preferably both methods should be carried out and compared.
4.3.1 DDM check of ADU O/P
At each antenna feed output of the ADU the measured DDM is a result of the SBO/CSB ratio
according to the formula
20dB
A B
VECTOR VOLTMETER
From cabinet
CSB BNC o/p
DIR. COUPL.
Antenna cable under test
Antenna