Enterprise Control Systems Secures Contract to Supply Microwave Downlink Systems to the French Gendarmerie Nationale

Enterprise Control Systems (ECS) is pleased to announce a new contract with the Direction Generale de la Gendarmerie Nationale. The contract will include, but not be limited to, 12 helicopter downlink transmitters complete with all accessories for installation on a new fleet of Eurocopter EC135 helicopters, along with a range of ground-based receive systems. ECS will provide a wide range of receive equipment to suit the wide and varied requirements of the gendarmerie. The receive equipment will include portable hand held systems, pelicase mounted, transportable systems and rack mounted fixed stations utilising antenna diversity improvement to achieve maximum range of operation. The equipment to be provided as part of the contract is detailed below. For further information about any of the equipment please do not hesitate to contact ECS.

Downlink transmitter

The system is fully modular and uses four main component parts; the modulator, power amplifier, antenna and controller. The modulator contains two MPEG 2 encoders, which accept up-linked signals or signals from onboard cameras. The system can be configured for two-channel operation with 16QAM modulation or single channel QPSK. The signal(s) are multiplexed onto a single radiobearer along with GPS information to be carried over the link. This information is used to switch the multi-sector receive antenna on the ground. The multi-sector antenna uses no moving parts to allow long-term reliable operation. The system is now also available to carry high definition signals.

Fixed base station receiver

The GPS signal coming down from the helicopter is used to steer a multi-sector receive antenna operating in the required band. The antenna will lock onto the signal and track the helicopter within a period of five seconds.
To ensure fluency of the signal each sector of the antenna array will make contact prior to the break of the existing signal. The antenna array, model number MSA6, is fixed vertically onto a 54mm pole and connected via a multi-way cable to the antenna controller. The antenna controller is housed in a 19in x 1U rack mount format and features a display of the sector in operation as well as the facility to override the GPS control signal or operate in omni-directional mode. The receiver is housed in a matching 19in x 1U unit. In order to overcome the difficulties normally associated with insertion loss at higher RF frequencies, the first phase of down-conversion is undertaken in the outdoor antenna unit. The resultant UHF signal can then be carried up to 200m to the indoor receive equipment via low loss co-axial cable.

Handy view receiver

The handy view receiver has been designed for highly portable reception of downlinked data signals. Utilising the latest technology in miniaturisation, the fully-integrated receiver incorporates a down-converter, demodulator and decoder with a high quality LCD display. The unit is normally used to receive over a range of up to ten nautical miles, which can be extended with diversity reception via an external down-converter and antenna system.

Portable briefcase receiver

For medium range operations (typically 20 nautical miles) a pelicase-mounted receiver has been offered and this also forms part of the long-range system described below. The pelicase has a built-in ruggedised LCD display and audio loudspeaker. The display is switchable to display either of the down-linked channels as required. This is also removable and can be used on a cable outside the briefcase if required. The receiver is powered from onboard lithium ion batteries, with the facility to power from an external vehicle supply or AC charger. All video and audiosignals are presented on the front panel for recording or external display.

Transportable receive system

This is suitable for obtaining long-range transmissions of 50 nautical miles to 200 nautical miles, depending on frequency. The upgrade system uses a five-sector antenna (six-sector above 4GHz) with directional antennas seamlessly switched to receive the signal from any direction. An uplook antenna is also fitted to receive from the helicopter if flying above the antenna. The portable antenna controller controls the antenna and this can be DC powered to be used alongside the briefcase receiver for long-range operations. The antenna system is mounted on a tripod to gain elevation and for ease of operation. The antenna does not use any moving parts, allowing long-term reliable operation. The whole system can be provided in rack mount form as a fixed installation. In this case the antenna can be installed high on a tower or mast for maximum range.

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