ASTi ACU2 Manual
Revision A
Version 0
April 2022
Document DOC-HW-AV2-UG-A-0
Advanced Simulation Technology inc.
500A Huntmar Park Drive •Herndon, Virginia 20170 USA
(703) 471-2104 •asti-usa.com
ACU2 (v2)
Technical User
Guide
iv
Revision history
Date Revision Version Comments
4/4/2022 A 0 Initial baseline version.
v
vi
Contents
1.0 Introduction 1
2.0 Physical description 3
2.1 ACU2 (v2) with bezels 3
2.2 ACU2 (v2) without bezels 5
2.3 Weight 5
2.4 Front panel 5
2.4.1 Audio interface: DB-15 pinout 6
2.5 Rear panel 6
2.5.1 Serial ports 7
2.5.2 Status indicator lights 8
2.5.3 DIP switch positions 8
2.5.4 ACENet connection 9
3.0 Audio input and output 11
3.1 Audio input 11
3.1.1 Microphone power 12
3.1.2 Input frequency response 13
3.2 Audio output 13
3.2.1 Audio isolation characteristics 14
3.2.2 Output frequency response 14
4.0 Control input and output 15
4.1 Control input 15
4.1.1 Control input used as a digital input 16
4.1.2 Control input used as analog input 16
4.2 Digital output 17
4.2.1 Digital output circuitry 17
5.0 Typical headset connections 18
vii
5.1 Mono headset connection 18
5.2 Stereo headset connection 18
6.0 Software configuration 19
7.0 Earth-ground the ACU2 (v2) 20
8.0 Update firmware 21
9.0 Rackmount ACU2 (v2)s 22
9.1 Power daisy chain 23
9.2 Bottom mounting diagram 25
10.0 Specifications 26
10.1 Power requirements 26
10.2 Memory devices 27
10.3 Temperature and humidity ranges 27
10.4 Reliability 27
Appendix A: Warranty information 28
A-1 Repairs and returns 28
1.0 Introduction
The ACU2 (v2) is a compact, 48 kHz digital and audio distribution module that connects
remotely located operator stations and live radios to the ACENet network. The ACU2 (v2) is
compatible with Telestra platforms. The ACU2 (v2) provides low noise, analog-to-digital con-
version, and low-latency audio distribution.
The ACU2 (v2) integrates press-to-talk (PTT) units, volume controls, simulated com-
munication panels, handheld terminals (HHTs), and live radios into the simulated com-
munications environment.
The ACU2 (v2) supports the following features:
lStereo support: stereo operation (i.e., independent left and right output) is supported on
a single DB-15 connector, which reduces cabling complexity and installation footprint
for applications requiring stereo operators.
lCompact footprint: each device supports four configurable mono or stereo operator pos-
itions in a single compact unit, which fits easily on a desktop. Alternatively, rackmount
two devices side by side in 1U 19" rack space.
lHigh-fidelity audio: 48 kHz digital audio and balanced pro-audio interfaces.
lSoftware-based configuration: software-adjustable amplifier or preamplifier gains and
microphone power for easy, direct connection to military and commercial headsets and
a wide variety of audio and communication systems and peripherals.
lSerial data ports: control interface for ASTi hand-held terminals (HHTs), simulated
panels, and live radio control.
lIntegrated I/O: configurable digital and analog input/output (I/O) for direct connection
of PTT units, volume control, switch detection, radio PTT activation, and other control
applications.
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.0 Physical description
This chapter provides a physical description of the ACU2 (v2):
lDimensions
lWeight
lDiagrams
lFront and rear panels
lPinouts
2.1 ACU2 (v2) with bezels
The ACU2 (v2) has two bezels, encompassing the front and rear panels. The ACU2 (v2) is
Conformitè Europèene (CE)/Restriction of Hazardous Substances (RoHS) certified. Remov-
ing the bezels voids the CE certification.
Figure 2, "ACU2 (v2) front bezel" below shows the ACU2 (v2)'s front bezel:
Figure 2: ACU2 (v2) front bezel
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
Figure 3, "ACU2 (v2) bezel side dimensions" below shows ACU2 (v2) bezel side dimen-
sions:
Figure 3: ACU2 (v2) bezel side dimensions
Table 1, "ACU2 (v2)s with bezels" below shows the length, width, and height of ACU2 (v2)
devices with bezels:
Specification Measurement
Length (i.e., depth) 7.9"
Width 7.489"
Height 1.724"
Table 1: ACU2 (v2)s with bezels
Figure 4, "ACU2 (v2) dimensions" below shows ACU2 (v2) height and width dimensions:
Figure 4: ACU2 (v2) dimensions
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.2 ACU2 (v2) without bezels
Table 2, "Specifications for ACU2 (v2)s without bezels" below shows the specification for
ACU2 (v2) devices without bezels:
Specification Description
Length (i.e., depth) 7.5"
Width 7.375"
Height 1.5"
Table 2: Specifications for ACU2 (v2)s without
bezels
2.3 Weight
A packaged ACU2 (v2) weighs 2 lbs. The power supply included with the ACU2 (v2) weighs
0.5 lbs.
2.4 Front panel
The front panel features four DB-15 connectors that are compatible with a variety of audio
and press-to-talk (PTT) devices:
Figure 5: Front panel of ACU2 (v2) without bezel
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.4.1 Audio interface: DB-15 pinout
Figure 6, "Interface connection DB-15 female" below shows a DB-15 pinout for the ACU2
(v2) audio interface:
Figure 6: Interface connection DB-15 female
2.5 Rear panel
Figure 7, "Rear panel of ACU2 (v2) without bezels" below shows the ACU2 (v2) rear panel:
Figure 7: Rear panel of ACU2 (v2) without bezels
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.5.1 Serial ports
The ACU2 (v2) has two serial ports that provide a control interface for ASTi handheld ter-
minals (HHTs), simulated panels, and live radio control. Figure 8, "RJ-12 pin out: RS-422
mode" below shows an RJ-12 female serial connection in RS-422 mode:
Figure 8: RJ-12 pin out: RS-422 mode
Figure 9, "RJ-12 pin out: RS-232 mode" below shows an RJ-12 female serial connection in
RS-232 mode:
Figure 9: RJ-12 pin out: RS-232 mode
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.5.2 Status indicator lights
The ACU2 (v2) LED indicator lights display the ACU2 (v2)'s status:
LED Lights Location Status
Flashing green Bottom Normal operation.
Red Top Internal board failure.
One red flash + three
green flashes
N/A No LAN link.
Table 3: ACU2 (v2) status indicator lights
2.5.3 DIP switch positions
Dual in-line package (DIP) switches toggle between normal operation mode and firmware
update mode. For additional guidance, go to Section 8.0, "Update firmware" on page21.
Table 4, "DIP switch positions" below shows DIP switch positions:
Position Status
Position 1 down allows for firmware updates.
Default position for normal operation.
Table 4: DIP switch positions
8 Copyright © 2022 Advanced Simulation Technology inc.
ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.5.4 ACENet connection
The ACU2 (v2)'s ACENet port connects to an ACENet-compatible switch via a Category 5e
(CAT5e) cable or better.
Device Cable Length
ACU2 (v2) 100 meters (328 feet)
Server 100 meters (328 feet)
Table 5: Maximum cable length to ACENet switch
Important: Customer-made cables are the primary reason for product failure. ASTi recom-
mends high-quality, manufactured CAT5e cables.
Alternatively, the ACU2 (v2) can connect directly to the Telestra server using a crossover
cable.
2.5.4.1 RJ-45 ACENet connection
Figure 10, "RJ-45 ACENet connection pin out" below shows an RJ-45 ACENet connection
pinout:
Figure 10: RJ-45 ACENet connection pin out
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
2.5.4.2 ACENet indicator lights
The ACENet LED indicator lights display the port status:
LED Light Status
Solid green Network link.
Flashing green Network activity.
Solid or flashing
amber
One ACENet device per network functions as the ACENet master and is iden-
tified with a flashing amber light. All other ACENet devices should report a solid
amber light.
Table 6: ACENet indicator lights
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
3.0 Audio input and output
The chapter discusses ACU2 (v2) audio input and output specifications.
3.1 Audio input
Table 7, "Audio input characteristics" below shows ACU2 (v2) audio input characteristics
and values:
Input Impedance 830 ohms single-ended (1.6K ohms differential)
Input Level 6.5 Vpp single ended (6.5 Vpp differential)
Input Gain -8 dB, +2 dB to +57 dB; default value of 40 dB; software configurable
Note: The ACU2 (v2) gain covers a total range of 65 dB. Between +2 dB and
+57 dB, the gain can be set in 1 dB steps. A value of -8 dB is available for input
signals greater than line level. The range -8 dB to +2 dB cannot be selected as
a function of design.
Microphone Power +12 VDC; off by default; software-enabled
Frequency
Response
20 Hz to 20 kHz, +/- 1.5 dB
Table 7: Audio input characteristics
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ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
3.1.1 Microphone power
In Telestra systems, microphone power is set in the Remote Management System (RMS).
Input levels can be adjusted in the RMS to accommodate line level signals as well as micro-
phone level signals. R1 and R2 connections are only active when power mode is enabled in
the software:
Figure 11: Microphone power diagram
Caution: Do not connect a microphone requiring phantom power to an ACU2 (v2) device,
as this will damage the microphone. If you are unsure of the difference between microphone
power and phantom power, contact the microphone manufacturer or ASTi before connecting
equipment. Most military headsets use microphone power.
12 Copyright © 2022 Advanced Simulation Technology inc.
ACU2 (v2) Technical User Guide (Rev. A, Ver. 0)
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