Northern Airborne Technology N301A - Manual (Page 26)

N301A-000 Audio Controller
SM45 Installation and Operation Manual
Section 3 Rev: 1.00 Issue 4 Page 3-3
ENG-FORM: 806-0112.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
3.3.4.1 ICS Volume Control
All ICS audio is controlled by the front panel ICS volume control, and may be varied to suit conditions.
The ICS volume control adjusts the level of the user’s local ICS audio and the incoming summed tie-line
audio. The user’s outgoing ICS audio is unaffected.
3.3.4.2 VOX Control
The VOX Control selects the mode of operation of the intercom mic. When the control is in the centre of
its range, the intercom is in the VOX mode (voice activated). As the control is rotated counterclockwise,
the system becomes more sensitive, until in the fully counterclockwise position it is in HOT mode (on
constantly). As the control is rotated clockwise, the sensitivity decreases, until at the fully clockwise
position it is in PTT mode (activated by cyclic or foot switch closure). Activation of the ICS PTT switch will
override the VOX setting.
VOX control will provide detection of mic signals up to 250m Vrms on the 150 ohm mic input or 0.25 mV
on the 5 ohm mic input.
3.3.4.3 HOT MIC mode Caution
If the Andrea Tie Line option has been selected at installation, the loading effect that occurs when
multiple mics are active at the same time will cause the intercom level to drop, resulting in lower intercom
audio at all stations. To minimise the loading effect, intercom operation should be restricted to one active
microphone at any time.
This problem will not occur if NAT tie lines have been selected at the time of installation.
3.3.4.4 Private ICS (PVT) - Andrea Tie Lines only
The N301A has a secondary ICS channel, configured at the time of installation, which provides PVT
intercom operation between selected stations. PVT intercom is selected by rotating the TX selector
switch to the PVT position and activating the radio PTT switch. Only stations selected to PVT will hear
this audio.
3.3.5 Direct Audio Inputs
The N301A provides four inputs for connection of warning/alerting signals; two are controlled by radio
volume, and two are fixed inputs. Only input DIRECT 3 will be audible in EMER mode.
3.3.6 Cockpit Voice Recorder
The N301A series of audio controllers provide an output to an external Cockpit Voice Recorder. This
allows all audio signals passed through the Audio controller to be recorded for later playback.
Section 3 ends