LOCALIZER AND GLIDE SLOPE MODE

TM 11-6625-2975-40

1-17.

AUDIO MODULATION GENERATOR OPERATION. (CONT)

A 1020-Hz audio tone can also be added to the composite audio modulation signal. The 1020-Hz audio

tone simulates an identification signal. The 1020-Hz signal is combined with the other two modulation

signals in analog board A2A2.

In VOR mode, FM modulation can be removed from the standard 9960-Hz FM tone by depressing the

9960 Hz key.

Analog board A2A2 also supplies the composite modulation signal to a COMP connector on the rear

panel and a 30-Hz reference signal (VOR mode only) to an AUX connector on the rear panel.

LOCALIZER AND GLIDE SLOPE MODE

In either Iocalizer or glide slope mode, TDM board A2A3 generates 90- and 150-Hz signals. These

signals are supplied to analog board A2A2 together with a Iocalizer or glide slope mode analog control

signal. Analog board A2A2 filters the 90- and 150-Hz signals to produce the audio modulation signal

supplied to demodulator/ale assembly A3A2. For changing the difference in depth of modulation

(DDM), CPU programs TDM board A2A3 to modify the amplitudes of the 90- and 150-Hz signals as

required.

In the Iocalizer mode, a 1020-Hz audio tone can also be added to the composite audio modulation

signal. The 1020-Hz signal is combined with the other two modulation signals on analog board A2A2.

MARKER BEACON MODE

Depending on keyboard selection and subsequent data from the cpu, TDM board A2A3 generates one

of three available audio modulation signals.

1. Outer marker tone 400-Hz audio tone

2. Middle marker tone 1300-Hz audio tone

3. Inner marker tone - 3000-Hz audio tone

A marker beacon analog control signal is generated by TDM board A2A3 and supplied to analog board

A2A2. Analog board A2A2 filters the audio tone and supplies the filtered tone to demodulator/alc

assembly A3A2.