Systems

Simple Point to Point Links

If there is a line of sight from the camera to the control room, then a single channel link can be installed near the camera to transmit the video and telemetry directly. A similar unit, installed at the control room, receives the video and transmits the reverse telemetry.

A large number of equipments can be installed at the video receive point. There are 38 channels available in the 31 GHz band and frequencies can be re-used every 15 degrees without interference. This results in a total capacity of over 900 simultaneous, full resolution, videos.

Use of Collecting Points

However in real systems there is often no line of sight. This is where the multichannel link offers a simple solution.

Here, the video and telemetry for the cameras are transmitted using single channel links to a collecting point located on top of any convenient tall building or mast. A multichannel link is then used to transmit all the videos in real time on a single equipment to the control room. Repeaters can be used at intermediate points if the path length is long or if there are obstructions.

The combination of single and multichannel links has enabled video networks to be implemented using microwave transmission throughout. The diagram shown here illustrates an actual installation interconnecting four towns with three control rooms. Video, data and audio is transmitted in parallel throughout the system.