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Latest Firmware Version: 2.17

Technical User Guide

The following information is pulled from the ACU2 Technical User Guide. For a comprehensive overview of the ACU2, please see the full guide:

View Guide

The ACE Communication Unit – 2nd Generation (ACU2) is a compact 48 kHz digital and audio distribution device that connects remotely located operator headsets, speakers, control panels and other peripherals to a central Target via the ACENet architecture. The ACU2 evolved from the ACU to provide four-channel stereo support in a reduced size.

A comprehensive overview of the ACU2 can be found in the Technical User Guide

General Specifications

Compatible with Voisus, Telestra
Part Number ACU2-04-XX
Dimensions 7.9" length (depth) x 7.489" width x 1.724" height
Weight A packaged ACU2 weighs 2lbs. The included power supply weighs 0.5 lbs
Power Source Individual power supply, included.

Note: When daisy-chained, the ACU2 requires a different power supply. Contact ASTi for details.

Power Consumption +15VDC, 2 A
Mean Time Between Failure (MTBF) 108,100.75 Hours (COTS)
48,390.23 Hours (military)

Audio Input/Output

Audio Input

Impedance 4.6 kΩ
Level 3.25 Vpp max (6.5Vpp differential)
Gain -8dB, +2dB to +57dB, software configurable*
Microphone Power +12.5 VDC, software-enabled
Frequency Response 20 Hz to 20 kHz, +/-1.5dB

* The ACU2 gain covers a total gain range of 65 dB, with the range of +2 dB to +57 dB being settable in 1 dB steps, with -8 dB being available for input signals of greater than line level. The range -8 dB to +2 dB cannot be selected as a function of design.

Audio Output

Impedance 10 Ω
Current 0.201 A at 8 Ω
Gain -25dB to +10dB
Level 1.61 VAC rms into 8 Ω
Power 0.32 W at 8 Ω
Frequency Response 20 Hz to 20 kHz
Max. Output Signal 10 Vpp

Memory Devices

This device works as a transportation mechanism, passing audio from one device to another until it reaches the headset or computer; this device does not store the audio.


Type Size User Modifiable Function Process to Clear
Micro-controller Internal SRAM 69 KB No Used as RAM for an internal MCU Remove Power
Count to 30
Restore Power


Type Size User Modifiable Function Process to Clear
Micro-controller Internal 256 KB Yes Firmware None
Flash 8 Mb Yes Firmware None


RJ-12 Pinout for RS-422

(Serial Connection)

RJ-12 Pinout for RS-232

(Serial Connection)

DB-15 Connector

(Audio Interface)


ASTi warrants to the buyer and its customers that all items delivered and all services rendered hereunder will conform to the requirements hereof and will be free from defects. In addition to other remedies that may be available at law or in equity, the buyer may return to ASTi any nonconforming or defective items or require correction or replacement of the item, all at ASTi’s risk and expense. If the buyer does not require correction or replacement of nonconforming or defective items, ASTi shall repay such portion of the contract price or such additional amount as is equitable under the circumstances.

Warranty period: 12 months from shipment date