Air-to-Ground COFDM Systems ( Downlinks )

Video Downlink Systems

Navtech Systems Limited has been designing, manufacturing, supplying and installing video downlink equipment for more than 20 years and was a pioneer in long range air-to-ground microwave downlink systems. We developed unique technology that enabled high performance directional tracking antennas to be cost-effectively produced.  The company has acquired considerable experience in this specialist field, particularly amongst airborne surveillance operators involved in security provision for use with their helicopter surveillance aircraft. We have an established customer base of Police and paramilitary organisations covering the USA, Europe and the Middle East.

Our downlink systems utilise the latest COFDM digital radio technology with secure encryption. Ranges in excess of 100km can be achieved. Ground reception antennas can be in fixed diversity arrays or can be GPS-steered high gain units, depending on the application and performance requirements.

Navtech’s downlink equipment has been selected on multiple occasions to provide the principle video downlink facility for the security surveillance aircraft used at major sporting events around the World, including both Summer and Winter Olympic Games.

In the UK, Navtech has successfully provided and supported downlink equipment to Police Forces in London, Manchester, Merseyside, Durham, Northern Ireland and Leicestershire. In the days of analogue links, Navtech were the pioneers of GPS video encoding technology and developed the system that became utilised in virtually all UK Police aircraft to enable long range analogue links with automatically tracking ground-based antennas. In recognition of its achievements, Navtech was awarded a UK Government DTI ‘Foresight’ award to endorse the previous ‘Smart’ awards for our down link technology.

Technology – Digital Video Links

Since the migration of links to digital COFDM technology, Navtech has continued to develop and offer high performance solutions, now based primarily on diversity receive antenna arrays with no moving parts. We offer a proven ‘state of the art’ 10W transmitter for aircraft applications, capable of SD,  HD or IP  operations, that carries full aircraft approval. The system is installed and deployed in a variety of aircraft types around the World. Navtech has based its solutions on the DVB-T standards to enable interoperability and compatibility with other equipment whilst providing secure encryption for sensitive applications.

Reception Equipment – fixed receive sites and portable systems

The systems offered by Navtech include the latest generation MRC (maximal ratio combining) diversity technology to provide optimal reception capability. Central receive sites can be either non-tracking diversity antenna arrays or the more traditional GPS-based switched sector array. Of concern to Navtech has been the ability to receive images at one site from more than one aircraft simultaneously. With a GPS-based solution, each aircraft would require a dedicated antenna array, control system and receiver. Using a diversity array, one set of antennas can supply multiple receivers without any control system being required allowing simultaneous reception from multiple aircraft. In addition to central receive solutions, Navtech provides a range of equipment for portable applications and mobile command posts, again making use of MRC diversity.


The same diversity equipment that is utilised for portable ground receivers is also used for enabling digital up-links to an aircraft. A compact dual antenna diversity receiver is offered which can feed up-linked ‘ground camera’ images to the aircraft’s on-board video management system.

Turn-key’ System provision and support

Designing and supplying complete system level microwave link solutions for airborne surveillance operators on a ‘turn-key’ basis has been at the core of Navtech’s activities for the last 15 years. We are a specialist company in this field, employing highly experienced staff, dedicated to providing optimal solutions to a customer’s needs. We have the proven capability to support and service the equipment anywhere in the World.

Service and After-sales Support

To provide comprehensive after sales service to our customers Navtech has experienced, field service engineers who are available to investigate and resolve any reported issues at a customer’s site, World-wide.