Operating instructions

AVIONICS SYSTEM
B-10
The [Supp Tone] key allows each tone to be suppressed to simulate the Beam Lost’ flag alarm.
Repeated presses will step through the following sequence:-
90 Hz tone suppressed
150 Hz tone suppressed, 90 Hz tone restored
150 Hz tone restored. (neither tone suppressed)
Using the [Preset DDM] key
A choice of four preset DDM levels is available by pressing the [Preset DDM] key. These are
shown in the following table. The [Fly Lft/Rt] key (or the [Fly Up/Dn] key) and the [Supp Tone]
key are used as described above.
Preset DDM levels (with corresponding µA values)
Localizer
DDM 0 4.6% 9.3% 15.5%
µA
0 45 90 150
Glideslope
DDM 0 4.5% 9.1% 17.5%
µA
0 39 78 150
As well as showing the DDM value as a percentage, the Service Monitor display shows a µA
value.
Using the localizer Ident facility
To simulate the localizer ident signal press the [Ident] key on the ILS localizer menu. A tone of
approximately 1020 Hz is applied to the carrier frequency.
The depth of modulation can be changed by first pressing the [AM Depth] key and then entering
the required level using the data entry keys and the [%] terminator key or by adjusting the value
using the variable control.
The localizer position signals from the Service Monitor are disabled when the Ident facility is
active.
Marker beacon
Selecting the Marker Beacon function displays the marker beacon screen and menu shown in
Fig. B-4 on page B-6.
The default simulated Marker Beacon test signal has a 75 MHz carrier, amplitude modulated at
95% with one of three tones; 400 Hz, 1500 Hz or 3000 Hz for outer, middle or inner markers
respectively. The RF frequency, RF level, AM depth and AM frequency can be changed as
required.
Setting the RF frequency
The RF frequency of the Marker Beacon test signal can be set to any frequency within the range of
the RF generator (400 kHz to 1050 MHz).
Pressing the [RF freq] key will highlight the 'RF Freq:' legend on the display and allow the
indicated frequency to be changed by using the variable control, or by using the data keys to enter
a new value.
Setting the RF level
To change the RF level first press the [RF Level] key, then enter the required level using the data
entry keys or use the variable control to adjust the displayed frequency. See RF frequency and
level on page B-8.