ACP100-300-2 Audio Control Panel
Installation Manual Revision 01
Copyright 2013© Aerovalley Technologies 3
Section 1 - Description and Specifications
1.1 Purpose of Equipment
The ACP100-300 Audio Control Panel is specifically designed to allow the integration of commercial and aircraft radio
equipment into one aircraft audio system, using no external interfacing units. The ACP100-300 has daul microphone inputs
with adjustable gain, bias, relay keying and sidetone generation. It also provides six transceiver adjustable microphone and
audio outputs, all transformer isolated. Two switched and one unswitched audio inputs.
The ACP microphone amplifier is centred around an Analog Devices microphone pre-amplifier chip, which has variable
compression and noise gating circuitry. This allows signals to be amplified for optimum signal levels for further mixing and
buffering, to intercom and various radio systems that may be installed.
The frequency response has been tailored to help reduce the noise characteristics found in high noise turbine aircraft.
Transformer isolation of the aircraft microphone (typically a noise cancelling electret) allows complete isolation of DC and
longitudinal noise induced on the headset leads caused by direct radiation and ground loop interference induced into the
airframe (by alternators and other electrical equipment). This also provides the biasing voltage and correct impedance
matching to be presented to the head set microphone unit.
In operation the unit provides about 6 –10dB of improvement in the signal to noise quality of the pilots speech over the
original unit, improving the intelligibility of air to ground communication significantly, and also helps prevent the overdriving
of the radios fitted to the aircraft which causes distortion and RF splatter.
The pre-amplifier also contains a noise gate to mute the audio when microphone levels fall below a predetermined point,
allowing for noise to be reduced in multiple pilot systems with intercom facilities.
In the current model APC-1 there is provision for a second microphone input with FET muting of the second microphone
channel, to a buffer amplifier which feeds 6 output stages and an internal intercom buss system. There is also ‘fail safe’
bypass switching fitted in case of system failure allowing direct headset access to the prime radio unit in position 1.
Each of the 6 output stages has its own adjustable output level and transformer system to supply the correct isolated audio
level to the radios in the aircraft at the correct impedance of 150 ohms, allowing a wide variety of units to be used, from
standard VHF air radios through to CB UHF style units.
Features
All transceiver inputs and outputs are transformer isolated –minimises earth loop induced noise. All have a 2kV
breakdown voltage.
Operated on 28VDC electrical system.
Dual microphone inputs with keying relay contacts, (NO.), provide for every transceiver, PTT. and Microphone
Priority keying and ICS to primary microphone.
Two switched Nav inputs and a third unswitched audio input user selectable.
Accommodates a wide range of radio microphone output levels and impedances, 15mVPP –2.5VPP
1 x 50ohm outputs up to 0dbm is provided, (3x 150ohm Headsets)
Input microphone gain adjustable
Basic parameters are as per below
~ 10dB / Octave below 200Hz.
6dB / Octave 200 –300Hz.
12dB / Octave above 2200Hz.
Compression Ratio ~ 10dB.
Compression release time ~ 100mS
