NORMARC NM 7000 Series, Инструкция по установке и пусконаладке

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The sensitivity of DDM versus electrical phase error can be estimated using the following pro-
cedure:
1. Note the DDM value reported by the operator at the Field Test Set for the antenna pair
under test.
2. a) If the DDM value is positive (150 Hz dominance), insert a male-female (MF) N-adaptor
(-9°) in the antenna left side seen forward toward the Field test set.
b) If the DDM value is negative (90 Hz dominance), insert a male-female (MF) N-adaptor
(-9°) in the antenna right side seen forward toward the Field test set.
3. Note the new DDM value. (This value should have oposite polarity compared to the value
without the adaptor.)
4. Calculate the corresponding phase error (electrical degrees) from the formula
DDM
1
: DDM (%) measured in item 1.
DDM
3
: DDM (%) measured in item 3.
(Example values from NM3523B)
Example 1:
Item 1: A1/A12: +4.3% DDM
Item 3: A1+MF/A12: -2.0% DDM (MF in A1)
Example 2:
Item 1: A6/A7: -0.6% DDM
Item 3: A6 /A7+MF: +1.86% DDM (MF in A7)
Cable trimming length: 6.2 mm/°.
5.2.5 Phase and amplitude transfer measurement
Connect each antenna cable and monitor cable to LPDA load and source respectively. Utilise
a vector voltmeter or network analyser in a test set-up Figure 5-2
ϕ ° ( )
9
°
DDM
1
DDM
1
DDM
3
+
-------------------------------------------
=
ϕ
9
°
4.3
⋅
4.3 2.0 +
--------------------- 4.8
°
= =
ϕ
9
°
0.6
⋅
0.6 1.86 +
------------------------
1.7
°
= =