ACU-1 by Sine Systems, Inc.








		The ACU-1 is an eight stereo input by one stereo output audio switcher with level control capabilities via RS-232 commands. Input selectors can be programmed to interlock or mix. The system also incorporates silence sensors, parallel logic inputs, multiplex outputs, control relays, a clock/calendar and temperature sensing capabilites. Customized Automation System While the switcher can be operated manually, gain maximum power and flexibility by connecting one or more ACU-1’s to a single serial data port of a host computer. The simple ASCII command structure allows for rapid development of very powerful ‘one-off’ customized automation systems. Front panel indicators include left and right VU meters, channel selection indicators and left and right silence alarm status indicators. Rear panel screw terminals are mounted on removable connector boards for easy installation and removal. Other features include: 8 input by 1 output stereo switcher with summing output individual channel level control for up/down fading and cross fading automatic level control and input level presets 16 logic-level status inputs 8 relay outputs (momentary or maintained) internal clock/calendar synchronized to AC power and battery backed temperature sensing capability (with optional sensor) silence sensing with adjustable sensitivity exclusive "multi-drop" RS-232 allows up to 10 ACU's on a single serial port audio and I/O connections through depluggable connectors operates on 120 or 240 volts AC (±10%) at 50 or 60 Hz Audio I/O and Switching The ACU-1 is relatively sophisticated for an audio switching device. Audio switching tasks are handled intelligently and effectively without infringing on program source material. A variety of I/O options give the ACU-1 the ability to control or signal outboard equipment so that it is easily integrated in a complete automation system. The heart of the ACU-1 is an 8 x 1 stereo switcher. The two isolated audio outputs are driven by the audio output of this switcher. The switcher is a summing switcher--any or all of the inputs can be switched on at the same time. Each of the eight stereo inputs is factory configured for balanced operation at nominal ‘line’ level (-4 dBm to +10 dBm). By changing a socketed resistor network any or all inputs can easily be converted to ‘consumer level’ unbalanced inputs (-15 dBm). The ACU-1 has two sets of audio outputs that contain identical program material. Output levels are adjustable by internal trim pots between 0 dBm and +8 dBm. The factory is +4 dBm at 0 VU. The audio outputs are isolated and short circuit protected. Automatic Level Control The switcher contains an automatic level control (ALC) that acts to maintain the output level at approximately 0 VU. The ALC will adjust the gain down rapidly if the audio level is too high or raise it up slowly if the audio output level is too low. The operation is conservative and quite transparent regardless of the program material. Rather than use potentiometers for level presets on each input, the ACU-1 uses a technique we call virtual level presets. By storing the gain of each channel at critical points in time and restoring that gain from memory at appropriate times, audio dips and bursts are virtually eliminated during switching. Silence Sensors The ACU-1 contains individual silence sensors for both the left and right output channels. The audio detection threshold and alarm delay times are set through data commands. Presence and loss of audio are indicated by LED’s on the front panel of the ACU-1 and relay contacts on the rear panel. Control Outputs There are eight general purpose control relays in the ACU-1 that can be used to control outboard equipment. The relays are operated by data commands and the relay action can be momentary or maintained (latched). The ACU-1 has eight open collector outputs that follow channel selection called multiplex outputs (MPX). The open collector can be used to select a channel on an external device when an audio channel is selected on the ACU-1. Time and Temperature The ACU-1 contains a real time clock that is synchronized to the 50/60 Hz AC power line and battery backed. The ACU-1 also has a calendar that can automatically adjust the time between Standard and Daylight Savings Time. An external temperature sensor is available for the ACU-1. The sensor comes with a weatherproof capsule and 100 feet of shielded cable. System Requirements The ACU-1 is not designed for any specific operating system or hardware platform. The programming interface is a set of ASCII commands that can be generated by most any computer. The host system must have one RS-232 serial port to communicate with the ACU-1. However, multi-drop RS-232 allows the operation of up to ten Audio Control Units from a single serial port. The ACU-1 requires a single grounded power supply outlet for power. The power supply is adjustable for either 120 or 240 volts AC via internal jumpers. The factory setting is for 120 volts AC.