©1999 Navia Aviation AS 21833-3.4 Maintenance Procedures
OPERATING MANUALNORMARC 7013
INSTRUMENT LANDING SYSTEM
C-5
(g) Return the sideband power to normal.
3. Course position alarms.
(a) Connect the PIR to measure DDM in the carrier feedline (CSB test connector).
(b) Using the PMDT, open Test DDM window, click on TX1 dominance Off button to activate
90 Hz predominance (assuming transmitter 1 is active to the antennas). If necessary adjust
Inc or Dec until the monitor course position channel has just passed the threshold of alarm.
Measure and record the carrier feedline DDM value on Navia Aviation Form “Localizer Monitor
Reference Data”. Confirm that the carrier feedline DDM is not more than established refer-
ence value. If not within tolerance, corrective action is required.
(c) Measure and record the course monitor DDM on Navia Aviation Form “Localizer Monitor
Reference Data”. The course monitor DDM can be observed in the currently active Test DDM
window as parameter MON1 CL DDM Nom. Note that no tolerance is established for this
entry. It is used only to detect trends.
(d) Repeat the procedure in steps (b) and (c) with the TX1 dominance button activated to 150
Hz.
(e) Restore the TX1 dominance button to off.
4. Modulation level alarms.
(a) Reduce the composite carrier modulation (90 + 150 Hz) until the monitor is in low modula-
tion percent alarm.This is accomplished from the PMDT: Open the TX Adjustments window.
Select COURSE Mod Bal (for active transmitter to antenna).Note the 4-digits value. Measure
the carrier modulation, using the modulation meter connected to the CSB COU front panel
test connector. Then reduce the 4-digits number followed by Update. Confirm that the modu-
lation percentages are not below the operating tolerance stated in chapter 3.
(b) Repeat step (a) for high modulation percent alarm. Confirm that the modulation percent-
ages are not above the operating tolerance in chapter 3.
(c) Restore the carrier modulation to normal (original 4-digits value).
5. Rf level alarms.
(a) Reduce the carrier power until the monitor is in rf low-level alarm. This is accomplished
from the PMDT: Open the TX Adjustments window. Select COURSE RF Power (for active
transmitter to antenna). Note the 3-digits value.
(b) Then reduce the value of the 3-digits number followed by Update until the monitor chan-
nel CL is in alarm. Measure and record the COU CSB dc voltage at the transmitter test con-
nector.
(c) Measure the carrier power using the BIRD wattmeter connecting to the course CSB feed-
line inside the facility.
(d) Restore the carrier rf power to normal (original 3-digit value). Measure and record the car-
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