COFDM Antenna Control Unit

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Enterprise Control System

Antenna Control Unit

The Antenna Control Unit (ACU) has been developed to control a Multi-Sector Antenna (MSA) and interface with a Video Link Diversity Receiver (VLDR). An Enterprise Control Systems Ltd (ECS) ground receiver comprising of these parts provides a robust air-to-ground Coded Orthogonal Frequency Division Multiplex (COFDM) link at long ranges.

Antenna Control Unit
  • General Description
  • Technical Data

General Description

Global Positioning System (GPS) information of the air platform transmitter is multiplexed onto the transport stream of the ECS COFDM downlink. This GPS information is decoded in the ECS receiver and fed to the ACU. The MSA contains a number of high-gain receive sector antennas. The ACU compares the transmitter’s GPS position and ground receiver’s position to select the appropriate sector facing the air platform. A manual mode is also provided. If the downlink is lost, the ACU will command the MSA to cycle through each antenna sector until the downlink signal is regained.
Additional gain is achieved by the VLDR having a second antenna input for diversity reception. The best signal from the two receive inputs is taken on a carrier-by-carrier basis and in real time. The second antenna may be an MSA to provide maximum gain or an omnidirectional antenna to increase the amount of multipath received. The exact antenna configuration to provide optimal performance is dependant on the operation scenario and environment.
There are two versions of the ACU: for frequencies up to 3.5 GHz, a five-sector MSA controlled by the ACU 5-sector variant is used; for frequencies above 3.5 GHz, a six-sector MSA is recommended in conjunction with the 6-sector ACU variant. Both variants have the capability of controlling either one or two MSAs.
A GPS output is provided at the rear of the ACU unit. The NMEA 0183 RS232 output may be used for air platform positional monitoring or as an input into a moving map application.
The ACU is 19-inch rack mounted and may be used as part of a static rack receiver system with a pre-programmed ground GPS position. The ACU may also be installed in a flight case (as above) or as part of a soft case receiver for mobile or temporary applications; in this case the ACU is fitted with its own GPS receiver. The system may be adapted for maritime use by fitting the ACU with a GPS receiver and vector magnetometer.

Technical Data

Model Numbers: ACU-D-5S Frequencies up to 3.5 GHz
Frequencies above 3.5 GHz
GPS Display: Alt, Lat, Lon, heading, Speed of transmitter, bearing of link
Antenna Display: Antenna selected, auto/manual, channel selected
Control: Sector auto/manual selection, sector selection, chan nel selection, mains on/off
Power Supply: 12 VDC, 1.5 A - 4-pin XLR 240 VAC - IEC
Size: 1U x 19 inch
Weight: 2.2 kg approx.