Thales 421 - Calibration and Normalization of Integral Monitors

LLZ 421
Alignment Procedure LLZ−1F (Dip./Refl.) Operation and Maintenance
ILS 420
4−14 Ed. 01.10SOAC
4.4.3 Calibration and Normalization of Integral Monitors
NOTE: Before performing this procedure it is recommended to check alarm limits acc. 4.4.5.
a) Switch both TX on and set TX1 on aerial.
4.4.3.1 Integral Monitoring Posn. (DDM 0 %)
a) RF−level of the corresponding path on the SOAC (Fig. 4−2, 4−3) is set to amplitude of 3.6 Vpp
as described in 4.4.1.
b) Set indicated DDM to 0 by inserting phase adapters in coupling lines from dipoles. Watch the DDM,
measured with the portable DDM instrument connected to the output Pos. Integral of the integral
network in the antenna distribution unit (ADU).
NOTE: If any corrections are necessary, start with dipole pairs whose nulls have been corrected by
inserting phase adapters.
c) Open dialog ’Monitor1−Nominal Values’ and open dialog ’Monitor2−Nominal Values’. Enter the
measured values for ’EXEC CRS Position DDM’ and ’EXEC CRS Position SDM’.
d) Open dialog ’Transmitter1−Waveform Data#1’. Note down the value of ’CRS SBO Amplitude’. Set
it to 0. Set ’ILS Ident keying’ to 10 % and ’continuous’.
e) Send to Monitor1/2 the command ’Calibration, Executive CRS Position detector’.
f) Restore TX1 SBO setting of 4.4.3.1 d) back to normal.
g) Send to Monitor1/2 the command ’Normalization, Executive CRS Position detector’.
NOTE: The automatic normalization procedure runs only if the actual DDM and SDM values do not
vary to much from the nominal values !
4.4.3.2 Integral Monitoring Width (DDM 15.5 %)
NOTE: No adjustment. The value indicated by the monitor or the value measured with the DDM−
instrument at the output of the integral network is used as nominal value.
If necessary the value of 15.5 % may be apporximateded adding adequate cable pieces.
4.4.3.3 Adjustment of Position Nearfield Monitor, optional (if available)
a) Set the RF−level of the corresponding path on the SOAC (Fig. 4−2, 4−3) to amplitude of 3.6 Vpp
as described in 4.4.1.
b) Shift nearfield dipole position so that DDM 0.0 % is received. Measure DDM with field receiver.
c) Open dialog ’Monitor1−Nominal Values’ and open dialog ’Monitor2−Nominal Values’. Enter the
measured values for Nearfield (Position) DDM.
d) Open dialog ’Transmitter1−Waveform Data#1’. Note down the value of ’CRS SBO Amplitude’. Set
it to 0.
e) Send to Monitor1/2 the command ’Calibration, Executive Nearfield Pos. detector’ (or ’Executive
Ch. 4 Width detector’).
f) Restore TX1 SBO setting of 4.4.3.3 d) back to normal.
g) Send to Monitor1/2 the command ’Normalization, Executive Nearfield Pos. detector’ (or ’Executive
Ch. 4 Width detector’).