TECHNISONIC INDUSTRIES LIMITED
TDAP-611 Operating Instructions
TiL 15RE553 Rev. B
7
2.4
INTERCOM (ICS) SELECTION AND VOLUME CONTROLS
The ICS VOX knob selects how the intercom system is activated. In the VOX (Voice Activated)
mode, the audio produced by any of the microphones will break the squelch of the intercom and
the audio will be routed through the system. The threshold audio level required to break the
squelch is adjusted by this knob. Turning the knob more counter-clockwise makes the system
more sensitive to incoming mic audio. A fully counter-clockwise setting on the knob will leave the
intercom on at all times giving LIVE or HOT MIC operation. When set fully clockwise, the intercom
is in the KEYED mode and will only produce audio when the intercom PTT line is keyed.
While the co-pilot, pilot, and passengers have individual mic VOX gates (3 in total), they are
controlled from a common front panel control. Individual gating reduces the amount of unwanted
noise when the intercom is triggered and makes intercom communication more intelligible as a
result. The passengers may have their VOX threshold offset by an internal adjustment (PAX
VOX) to accommodate differing headset types or ambient noise conditions.
With only a single TDAP-611 Audio Panel, best operation of all ICS functions is obtained when
the microphones are all of the same type (or have very similar characteristics). Headsets with
significantly different microphones or earpiece efficiencies make it difficult to achieve satisfactory
control adjustments for all users, unless they also have individual level controls. Good quality
headsets (such as David Clark, Telex, or Bose), with noise reducing, amplified dynamic
microphones and individual headset volume controls, give the most effective and user-adjustable
performance and minimal system difficulties. The use of “clone” headsets that visually resemble
these higher quality units, but have much poorer electrical and acoustic performance, is strongly
discouraged, as the entire system operation will suffer. This is especially true under high noise
conditions.
The ICS LEVEL knob controls the intercom volume level for all users. Fully clockwise is the
maximum volume level and fully counter-clockwise is the minimum.
The TDAP-611 contains two Intercom systems, one that services the Pilot and Co-pilot and one
that services the passengers. If the ICS VOX knob is pushed in, the two Intercom systems are
interconnected and the crew members can communicate with the passengers through the
intercom system. If the ICS VOX knob is pulled out and the indicator is illuminated, the Crew and
Passenger intercom systems are isolated from one another on completely separate intercom
systems and communication between the two groups through the intercom system is not
possible.
2.5
PA CONTROLS
To select the PA to transmit on, press the PA pushbutton. When selected, the associated
indicator will be illuminated. Selecting the PA pushbutton deselects any active COM transceiver;
however, the COM transceiver set-up is stored in memory, so deselecting the PA pushbutton will
restore the original set-up. When the PA is selected, all transmit audio will be delivered to the PA
system.
If the PA is selected for longer than 30 seconds, the PA select pushbutton indicator will begin to
flash to warn users they will be talking on the PA system and not a radio. This is a safety feature to
prevent accidental transmission over the PA system, which can have significant repercussions.
