Thales 421 - Calibration and Normalization of Integral Monitors

LLZ 421
Alignment Procedure LLZ−1F (LPD) Operation and Maintenance
ILS 420
7−14 Ed. 07.08SOAC
7.4.3 Calibration and Normalization of Integral Monitors
NOTE: Before performing this procedure it is recommended to check alarm limits acc. 7.4.5.
a) Switch both TX on and set TX1 on aerial.
7.4.3.1 Integral Monitoring Posn. (DDM 0 %)
a) RF−level of the corresponding path on the SOAC (Fig. 7−2, 7−3) is set to amplitude of 3.6 Vpp
as described in 7.4.1.
NOTE: If any corrections are necessary, start with dipole pairs whose nulls have been corrected (e.g.
by cable cutting or inserting phase adapters. Refer to 7.3.3.)
b) Open dialog ’Monitor1−Nominal Values’ and open dialog ’Monitor2−Nominal Values’. Enter the
values for ’EXEC CRS Position DDM’ and ’EXEC CRS Position SDM’.
c) 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’.
d) Send to Monitor1/2 the command ’Calibration, Executive CRS Position detector’.
e) Restore TX1 SBO settings of 7.4.3.1 c) back to normal.
f) 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 !
7.4.3.2 Integral Monitoring Width (DDM 15.5 %)
a) RF−level of the corresponding path on the SOAC (Fig. 7−2, 7−3) is set to amplitude of 3.6 Vpp
as described in 7.4.1.
b) Open dialog ’Monitor1−Nominal Values’ and open dialog ’Monitor2−Nominal Values’. Enter the
values for ’EXEC CRS Width DDM’.
c) Open dialog ’Transmitter1−Waveform Data#1’. Note down the value of ’CRS SBO Amplitude’. Set
it to 0.
d) Send to Monitor1/2 the command ’Calibration, Executive CRS Width detector’.
e) Restore TX1 SBO settings of 7.4.3.2 c) back to normal.
f) Check and set DDM indication to 15.5 % with R383.
NOTE: The procedure enables to calibrate to 15.5 % within a range of about 15 % to 16 %. This is nor-
mally achieved by an accurate adjustment.
g) Send to Monitor1/2 the command ’Calibration, Executive CRS Width detector’.
7.4.3.3 Adjustment of Position Nearfield Monitor, optional (if available)
a) Set the RF−level of the corresponding path on the SOAC (Fig. 7−2, 7−3) to amplitude of 3.6 Vpp
as described in 7.4.1.
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
values for Nearfield DDM.