COBHAM DACS User manual

CONFIDENTIAL AND PROPRIETARY TO COBHAM
Digital Audio Control System
(DACS)
OPERATOR’S MANUAL
REV 1.10
IMPORTANT NOTICE
Chelton Avionics Inc. doing business as Wulfsberg
Electronics Division is responsible for full distribution and
revisions of ICA's (Instructions for Continued Airworthiness).
For inquires regarding the content and currency of this
manual contact Wulfsberg Electronics Division, 6400
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SEALED
2012.03.20 
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Published on
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DACS Digital Audio Control System
Operators Manual
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Page i
Prepared By: Checked By: Approved By:
Revisions
Rev.
ECR No.
Date
Description of Change
1.10 ECR11065 3-8-12 ECR 11065: Rewrote Section 3.5.1
1.00 10-7-10 Initial release.
Charles Horkin
2012.03.09 
16:44:52 -08'00'
Allan prince
2012.03.09 
17:31:23 -08'00'
Zack Pahlman
2012.03.13 
17:50:58 
-07'00'
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DACS Digital Audio Control System
Operators Manual
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Page ii
Table of Contents
Section Title Page
1 Introduction.............................................................................................. 1
2 System Information ................................................................................. 1
3 ACP Controls and Indicators ................................................................. 3
3.1 ACP Faceplate Illumination .................................................................. 4
3.1.1 Day Mode Illumination................................................................... 4
3.1.2 Night Mode Illumination..................................................................4
3.1.3 NVG Mode Illumination...................................................................5
3.1.4 Legends Illumination ......................................................................5
3.2 Built-In Tests (BITs)..............................................................................5
3.2.1 Power-Up Built-In Test (PBIT)........................................................5
3.2.2 Continuous Built-In Test (CBIT) .....................................................5
3.3 Operational Criteria ..............................................................................5
3.4 ACP53 Front Panel Controls ................................................................6
3.4.1 Transceiver Radio Controls.............................................................6
3.4.2 Transmit Active Indicator.................................................................7
3.4.3 Receiver Radio Controls (ACP53 and ACP54 only)........................7
3.4.4 Mode Control (Users 1 and 2 Only).................................................8
3.4.5 Emergency Mode............................................................................ 8
3.4.6 VOX Control.................................................................................... 9
3.4.7 Transmit Selector Switch ..........................................................… . 10
3.4.8 TX/ICS PTT Switch ....................................................................… .10
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Page iii
3.4.9 ISO/CALL Switch ........................................................................10
3.4.10 RX/ICS Volume Control ...........................................................… 11
3.4.11 CALL Indicator ............................................................................11
3.4.12 ISO Indicator ...............................................................................11
3.5 Isolation (ISO) Mode...........................................................................12
3.5.1 Crew/Passenger Talk Groups .......................................................12
3.5.2 ISO/CALL Switch ..........................................................................12
3.5.3 Call Priority................................................................................… 13
3.6 Transmit Features ..............................................................................13
3.6.1 User Priority ..................................................................................13
3.6.2 Transmit Time-Out ....................................................................... 13
4 Aural Alerts ............................................................................................14
4.1 Remote Alert Cancel (not on ACP)......................................................14
4.2 Remote Alert Inhibit (not on ACP) .......................................................16
4.3 Other Remote Switches (not on ACP).................................................16
5 ACP53 Specifications............................................................................16
5.1 Electrical Specifications......................................................................16
5.2 Physical Specifications ......................................................................17
5.3 Environmental Specifications .............................................................17
6 Abbreviations and Acronyms...............................................................18
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1 Introduction
Information in this manual consists of the functional and operational procedures for the
COBHAM Digital Audio Control System (DACS).
2 System Information
DACS is a communications management system that distributes and controls all the
audio in an aircraft. This overview provides a basic understanding of how the system
functions.
CAUTION:
It is important that you confirm the specific criteria associated
with this installation with your installing agency.
At installation, a computer using COBHAM Device Configuration Software (DevCS) is
used to program specific user criteria for the required communications setup. The
number of radios, number and type of users, headset impedances, VOX control for the
passengers and numerous other options are defined at this time.
The Audio Management Unit (AMU) manages the audio to and from all transceivers,
receivers and audio warning sources; enables the transmission of microphone audio to
a selected transmitter and distributes all Inter-Communication System (ICS) audio.
The Audio Control Panel (ACP) is the operator interface which can be any
combination of up to six ACP53s.
The Remote Memory (RM) connects to the AMU and stores the system's
configuration and aural alert files remotely. This allows replacement of the AMU
without the necessity of reconfiguring the replacement unit.
An optional Passenger Intercom Amplifier (PIA) is available to allow up to twelve
additional passengers to be connected to the system.
The AMU, RM and PIA have no direct operator interface and information on these units
is available in their applicable Service Manual.
The following figure illustrates a typical DACS system hardware configuration however it
will vary depending on the specific criteria required.
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Figure 1: Typical Digital Audio Control System
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3 ACP Controls and Indicators
ACP53-xxx
The ACP53-xxx is an Audio Control Panel for the DACS. The ACP51-xxx and
ACP54-xxx are variants of the ACP53-xxx.

ACP51-xxx
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ACP54-xxx
All ACP installed features operate in the same manner unless otherwise noted in the
text of this manual or the feature is unique to a particular model.
The faceplate of the ACP supports replaceable legends for the receivers and the
transceivers. This enables the installing agency to change the names of the radio
controls to match the radios installed on the aircraft.
3.1 ACP Faceplate Illumination
The illumination of the ACP faceplate indicators (selected Transceiver, TX, ISO and
CALL LEDs) depend on the specific mode selected, Day, Night or NVG. The legends
illumination is controlled by the backlighting bus.
3.1.1 Day Mode Illumination
When in Day mode, the ACP indicators are at sunlight readable levels. By adjusting
the aircraft dimming bus either Day or Night mode level of illumination is available.
3.1.2 Night Mode Illumination
To enable Night mode adjust the aircraft dimming bus or select an external Night
mode switch. The ACP indicators illumination level is constant and at a significantly
reduced level compared to the Day mode levels.
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3.1.3 NVG Mode Illumination
To enable NVG mode select an external NVG mode switch. The ACP indicators
illumination level is constant and at a reduced level compared to the Night mode
levels.
3.1.4 Legends Illumination
The legends illumination is controlled by the backlighting bus.
3.2 Built-In Tests (BITs)
3.2.1 Power-Up Built-In Test (PBIT)
On power-up, the ACP runs a PBIT to confirm correct operation of the unit and all ACP
indicators will illuminate for a period of approximately three seconds.
If the ACP has not established connection to other components in the audio system
three seconds after the power is applied then the ACP indicators will extinguish until
connection is achieved.
3.2.2 Continuous Built-In Test (CBIT)
The ACP requires serial communication with the AMU. If serial communications with the
AMU is lost for more than 0.5 seconds all the ACP indicators will extinguish and remain
off unless communication is re-established.
3.3 Operational Criteria
It is important to be aware the functions described may differ depending on how the
AMU has been configured through the DevCS during installation. Within the audio
system the ACP may have different features depending on the user status of each
specific unit. Normally the pilot and copilot will be designated User 1 and User 2
respectively.
Confirm the specific criteria associated with this installation with your installing
agency.
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3.4 ACP 53 Front Panel Controls
3.4.1 Transceiver Radio Controls
The ACP has up to eight Transceiver Receive audio volume controls with
interchangeable illuminated labelling to allow selection of suitable legends.
Each control is an edge-lit rotary plastic knob that is used to control the volume for a
specific transceiver. Rotating the knob clockwise (cw) will increase the volume and
counter-clockwise (ccw) will decrease the volume. The master RX Volume control can
be used to effect a global adjustment to all Transceiver volumes (see section 3.4.10).
Each control has a push-on/push-off action to allow individual selection of the required
transceivers. In the on position the control knob is extended, the volume for the
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associated transceiver can be adjusted by rotating the knob and the illumination of the
triangular arrow will be at maximum. In the off position the knob is retracted (pressed
in), the volume is selected to the minimum value (off) and the arrow illumination is
minimized or off.
Above each control knob is a Transmit Access indicator which will illuminate green
when the associated transceiver is selected (by the transmit selector) and the ACP
has access to that transceiver. If access to that specific transceiver has been
restricted through the AMU DevCS the indicator will remain dark.
3.4.2 Transmit Active Indicator
The ACP has an NVIS Green B 'dead-front' TX indicator that illuminates when the
unit is transmitting on any transceiver.
3.4.3 Receiver Radio Controls (ACP53 and ACP54 only)
The ACP has up to eight Receiver audio volume controls with interchangeable
illuminated labelling to allow selection of suitable legends.
The receiver volume control is an edge-lit rotary plastic knob that is used to control the
volume for a specific receiver. Rotating the knob cw will increase the volume and
ccw will decrease the volume. The master RX Volume control can be used to effect a
global adjustment to all Transceiver volumes (see section 3.4.10).
Each control has a push-on/push-off action to allow individual selection of the required
receivers. In the on position the control knob is extended, the volume for the associated
receiver can be adjusted by rotating the knob and the illumination of the triangular
'arrow' will be at maximum. In the off position the knob is retracted, the volume is
selected to the minimum value (off) and the arrow illumination is minimized or off.
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3.4.4 Mode Control (Users 1 and 2 Only)
The mode control is a red three-position locking toggle switch that can be used by
Users 1 and User 2 only to select the unit’s operational mode, NORM (normal),
BK-UP (back-up) or EMER (Emergency). The locking mechanism prevents accidental
deselection of the currently selected mode.
On the other ACPs in the aircraft this switch has no function.
3.4.4.1 NORM (Normal)
When normal operation is required, both the User 1 and User 2 mode control switches
must be in the down (NORM) position.
3.4.4.2 BK-UP (Back Up)
When either User 1 or User 2 Mode switch is in the centre (BK-UP) position, the AMU
switches over to the back-up power supply and the system is placed into Back-up
Mode.
Users 1 and User 2 maintain full functionality via back-up microphone and
headphone amplifiers but all passenger ACPs and headset functions are disabled.
Any appropriate installed external indicator(s) will illuminate to warn the other users
that back-up (or emergency) mode has been activated.
3.4.4.3 EMER (Emergency)
Emergency Mode is activated if either User 1 or User 2 selects EMER. On all other
ACPs this switch has no function.
3.4.5 Emergency Mode
Emergency mode can be selected if either User 1 or User 2 selects EMER on the
ACP mode control switch, however the AMU will automatically select emergency
mode if it loses connection with the ACP of either User 1 or User 2.
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In Emergency mode, Users 1 and 2 maintain a reduced level of operation.
When In Emergency Mode, User 1 will be connected to COM1, NAV1,
Direct 1, Direct 2, Direct 3 and all alerts.
User 2 will be connected to COM2, NAV2, Direct 1, Direct 2, Direct 3 and all alerts.
Keyed intercom audio is maintained between Users 1 and 2 at a fixed level selected
through the DevCS at installation.
Any appropriate installed external indicator(s) will illuminate to warn users that
emergency (or back-up) mode has been activated.
3.4.6 VOX Control
The VOX control is a rotary control used to select the VOX level of the unit.
When the VOX control is rotated full cw the level will at maximum and when rotated fully
ccw to the detent position the level will be at minimum. When the VOX control is rotated
ccw past the detent position the ACP will be in the PRESET position.
3.4.6.1 PRESET
When the VOX control is set fully ccw beyond the detent the intercom audio will be in
the PRESET VOX position. The preset level is selected through the DevCS.
3.4.6.2 MIN (Hot MIC Operation)
When the VOX control is set fully ccw to the MIN (minimum) position the intercom audio
will be easily activated (take care not to rotate the control past the detent position into
PRESET).
3.4.6.3 PTT (Keyed ICS Operation)
Keyed ICS is activated when switched by an ICS PTT switch.
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3.4.6.4 VOX (Voice Activated)
Set the VOX control fully ccw and slowly rotate cw until the intercom just becomes quiet.
This setting will vary with ambient noise conditions as well as the quality and number of
microphones connected in the system.
3.4.7 Transmit Selector Switch
The Transmit (TX) Selector is a nine position rotary switch used to select the
transceiver for transmission.
When the TX Selector switch is turned fully ccw it will be aligned with the ICS
position. Each of the other positions will align with one of the selectable transceivers.
For further information see section 3.4.1.
3.4.8 TX/ICS PTT Switch
The TX/ICS PTT switch is a momentary center-off toggle switch labeled ICS (up) and
TX (down).
When the ICS/TX switch is in the ICS position the ACP will transmit on ICS Audio
irrespective of the position of the transmit selector switch.
When the ICS/TX switch is in the TX position the ACP will transmit on the ICS or
transceiver selected by the TX selector switch. 3.4.9 ISO/CALL Switch
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3.4.9 ISO/CALL Switch
The ISO/CALL button is a momentary push-button switch that can be used to enter
ISO (isolation) mode (crew only) or to call the crew when in ISO mode. For further
information on ISO mode, see section 3.4.
3.4.10 RX/ICS Volume Control
The master RX/ICS Volume control is a dual concentric knob. The upper (inner) knob
controls the ICS volume potentiometer and the lower (outer) knob controls the master
receive volume for the unit.
Rotating the ICS knob cw will increase the ICS volume and ccw will decrease the
volume.
The master RX pot affects all Transceiver and Receiver receive volumes. When rotated
fully ccw it reduces all receive volumes by 75% and increases them all proportionally as
it is rotated cw. When rotated fully cw the master volume is set to maximum.
3.4.11 CALL Indicator
The ACP has one dead-front CALL indicator that flashes to signify that another user is
calling when the system is in ISO mode.
The CALL Indicator will flash at 1 Hz for a Normal Call and at 3 Hz for a
High Priority call.
For further information on Normal and High Priority calls see section 3.5.3.
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3.4.12 ISO Indicator
The ACP has one dead-front ISO indicator that will illuminate when Isolation mode has
been selected. For further information on ISO mode, see section 3.5.
3.5 Isolation (ISO) Mode
Isolation means that the normal intercom audio communications path is temporarily
suspended. Isolation has no effect on any other audio source.
3.5.1 Crew/Passenger Talk Groups
The DACS DevCS configures the way the ISO/CALL switch operates. It is important
to be aware of the configuration set-up for your specific situation.
The system provides the ability to create two talk groups: crew, and passengers. Up to
three ACPs can be designated as crew –all others, regardless of the actual status of
the user are designated as passenger. The crew can use the ISO/CALL switch located
on their Audio Control Panel to initiate and cancel the talk group selection (ISO mode).
On the passenger Audio Control Panels the same switch acts as a call switch.
The PIA01 passenger interphone amplifier can also be connected to the AMU50 using
either the digital ICS tie line interface or the analog ICS tie line interface. Selection of
the interface between digital or analog is performed using DevCS. Analog selection is
primarily intended for interfacing to older legacy intercom equipment. The PIA01 is
designed to allow up to 12 additional passengers to share the DACS intercom system
on the passenger talk group.
Refer to the description of ISO/CALL Switch function for details on possible
configurations of the crew and passenger talk groups that can be selected using
DevCS.
3.5.2 ISO/CALL Switch
In each of the options listed below only the ACPs designated to crewmembers can be
used to select ISO mode. On all 'non-crew' (passenger) ACPs the ISO/CALL switch
will act as a CALL switch ONLY.
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Within DevCS the configuration of talk groups can be set up in multiple ways. DevCS
enables selection of virtually any combination of ACPs to the crew or passenger talk
groups. Limitations are:
At least one ACP must be assigned to the passenger talk group.
Any ACPs without users assigned to them cannot be selected to the crew talk
group.
PIA01 users are always connected to the passenger talk group.
In ISO mode, an example of three commonly used configurations (talk groups) are as
follows:
Single Crew: Either User 1 or User 2 is isolated from the remainder of the aircraft
(other crew and passengers) when the ISO/CALL switch is pressed. When User 1 or
User 2 is isolated, all ISO indicators on all ACPs will illuminate as will any external
isolation indicator.
Dual Crew: The crew are isolated from the cabin passengers. When isolated, the
crew (Users 1 and User 2) can communicate normally and the remaining passengers
can communicate amongst themselves but the two groups will not hear each other.
This will happen when either User 1 or User 2 of the crew presses their ISO/CALL
switch then all ISO indicators on all ACPs will illuminate, as will any external isolation
indicator.
Triple Crew: The three crewmembers can communicate normally but they
are isolated from the cabin passengers. The remaining passengers can
communicate amongst themselves but the two groups will not hear each
other. This will happen when any of the three crewmembers presses their
ISO/CALL switch then ISO indicator on all ACPs will illuminate, as will any
external isolation indicator.
When the ISO/CALL switch is pressed on a non-crew ACP it operates as a
call switch. When a CALL switch is pressed, the CALL LED will flash on all
ACPs, and a chime will sound in all headsets.
To end isolation mode, the ISO/CALL button is pressed again on one of the
crew ACPs. When isolation mode has ended the CALL and ISO indicators are
no longer illuminated and the chime function is deactivated.
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3.5.3 Call Priority
In ISO mode a passenger may use the call switch on their ACP to contact the crew.
When the ISO/CALL switch is pressed by a passenger, CALL will be indicated on the
crew ACP unit(s). The crew can cancel ISO mode to acknowledge the call or if the call
is not answered it can continue or be set and will automatically cancel after the DevCS
'call time out' period has expired. If the crew have not answered (i.e. cancelled ISO
mode) a subsequent call can be given High Priority status or override can be selected
using remote call and override buttons that can be connected to the AMU50.
The function of the CALL buttons on any passenger ACP can be configured
through DevCS to allow the CALL button to initiate a normal call, a high priority call or to
override the isolation mode.
3.6 Transmit Features
3.6.1 User Priority
If a user has keyed a specific transceiver no other user can access that transceiver
for the duration of the transmission.
3.6.2 Transmit Time-Out
The system has a stuck microphone (transmit key-line shorted to ground) timeout
feature. After 30 to 120 seconds (adjustable through the DevCS), the transmit key
input signal is overridden, the selected radio will stop transmitting and the transmit
indicator on the user’s Audio Control Panel will no longer be displayed. The timer is
reset once the transmit key-line is no longer grounded.
At installation, this feature may be disabled through the DevCS.
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4 Aural Alerts
Note: The aural alerts are configured through the DevCS and cannot be modified,
selected or changed in any way by the operator, or through the ACP. This information
is included for information purposes only.
Up to eight aural alerts can be configured through the DACS DevCS and can consist
of tones, voice messages or a combination of both, played once only or repeated.
Confirm the specific criteria associated with this installation with your
installing agency.
Aural alerts can be configured to repeat for a set number of times (up to five) or can
repeat continuously. Continuous aural alerts will continue to play until the trigger
condition has been resolved; otherwise an alert will stop after the set repetition
number and will not play again (unless the trigger condition is resolved and the alert
is reactivated).
If two or more alerts become active at the same time the priority of the alert (as
configured by the DevCS) will decide which alert plays first. If two or more alerts that
have been configured as 'highest priority' are triggered at the same time they will play
simultaneously.
The DACS DevCS is used to define which users will hear specific aural alerts.
4.1 Remote Alert Cancel (not on ACP)
CAUTION:
It is important to be aware of all possible implications if
the 'Audio Alert Cancel' switch is activated.
The DACS DevCS may be used to configure any audio alert generated by the AMU
as cancelable or not cancelable. A remote Alert Cancel switch may be installed in
the aircraft and if a cancelable alert is triggered this button can be used to cancel the
alert even if the trigger condition still exists. If the alert is cancelable, an alert must
still be played at least once before the cancellation can take effect and any new
cancelable alerts played after the switch is activated will be unaffected.
Note: If an Alert Inhibit switch has been activated no aural alerts will be played (see
section 4.2).
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4.2 Remote Alert Inhibit (not on ACP)
CAUTION:
When an Audio Alert Inhibit switch is activated, it is important to be aware that no
aural notification generated by the AMU will be given for any alert situation.
A remote Alert Inhibit switch may be installed in the aircraft. This switch is like an
on/off switch for the aural alerts generated by the AMU which in effect mutes all
tones/voice messages. Although the standard visual alerts will still be visible to the
pilot and copilot no other crew or passengers will receive audible notification of these
alerts.
4.3 Other Remote Switches (not on ACP)
Other remote switches and indicators may be installed. It is important to be
aware of the configuration set-up for your installation. Confirm the specific
criteria associated with this installation with your installing agency.
5 ACP53 Specifications
5.1 Electrical Specifications
Input Power 25.5 Vdc
0.25 A @ 25.5 Vdc
Lighting 27.5 Vdc
0.10 A @ 27.5 Vdc
Optional Panel Lights 5 Vdc
0.10 A @ 5 Vdc
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