The unit shall be constructed as a linearray of sixteen 4" full-range loudspeakers equipped with moisture resistant diaphragms. The individual loudspeakers shall be positioned according to a patented scheme.

All signal processing functions, necessary to properly drive a directivity controlled line-array with electronical aiming properties, shall be implemented onboard in order to reduce the overhead costs related to external connections. The complete electronics shall be mounted on a chassis which is placed in a separated compartment at the front-side of the enclosure. Electronics shall consist of an audio input module, two input / eight output channel DSP section, eight power amplifiers with protection circuitry (power amplifiers one through four shall drive one loudspeaker each, power amplifiers five through eight shall drive three loudspeakers each) and a switched-mode power supply.

The input section shall be transformer balanced. All necessary array signal processing shall be implemented in the digital domain by means of a 900MFLOPS 32bits DSP. The DSP shall realize appropriate output channel filters and delays. Besides the aforementioned, the DSP shall be able to realize EQ, pre-delay, volume and autogain, and compression as required. The DSP software and coefficients shall reside in non-volatile memory in order to facilitate adaptations and software updates.

The control unit shall be equipped with a fully isolated RS-485 based full-duplex serial network interface. This control unit shall serve three main functions:

• Remote monitoring of parameters like status of the DSP, amplifiers and loads, external pilot tone, status of the ambient noise sensing microphone, chassis temperature, ambient noise level, ambient temperature, control for the input section etc.
• Remote control of beam parameters, volume and analog pre-gain, pre-delay, EQ, autogain configuration and surveillance related parameters.
• Updating DSP software and factory unit programming.

The audio signal shall be connected to a 6p male 5 mm pitch cage clamp connector (as WAGO series 231). The RS-485 signal shall be connected to a 5p cage clamp connector of the same type as specified above. The unit shall be equipped with a 3p male IEC mains supply connector. All connectors shall be grouped together on the electronics chassis and shall be accessible from the front and the rear of the unit.

The enclosure shall be constructed of steel finished with an epoxy coating. At the back side of the enclosure a total of two bracket attachment points shall be provided (located near the outer ends). The protective front shall consist of a perforated steel grill which can be clicked onto six snap-in studs mounted on the enclosure.

The complete loudspeaker unit shall meet the following criteria:

Typical frequency range of the complete array 130 - 10k Hz on axis (+/- 3 dB), max. SPL at 30 m of 92 dBSPLcontinuous and 95 dBSPL peak, adjustable vertical beam shape is defined by the DDS (Digital Directivity Synthesis) algorithm, fixed horizontal opening angle of 130° (-6 dB, averaged 1k to 4k Hz).