Downlink Issues
Providing high quality video over analogue, digital or IP links is always challenging. With limited bandwidth to ground stations and beyond to Operation Control centers, video quality is often degraded with various encode/decodes and latency issues. A blocky and jumping video feed is never a good thing as we know from watching our own TV channels in the house over uncontended broadband!
Downlink Selection
Selection of the equipment will fall out from some basic questions….it must be simple to operate and designed for the missions it will be used for. Key questions to consider:
Where will the downlink go to?
Who will be viewing and how will they view the video feed?
What transmission medium will it be transmitted over?
What are the limitations of that medium?
What are my secure options?
The selection of the camera or gimbal is as important as the transmission system with the clever boxes in between to provide the lowest latency with highest quality Video. Answering these questions will save costs and a lot of tears!
Encoding Transcoding
Having selected the camera/gimbal system the next key piece of the jigsaw is the video/metadata compression hardware. Combining low latency video streaming solutions and H265/HEVC encoding/transcoding capabilities (such as those provided by Haivision products) combined with Secure Reliable Transport (SRT) protocol, will bring down bit rates to extremely low levels (as low as 100kbps). This enables high quality and low latency video to be transmitted over constrained networks such as satellite and other data networks.
Who’s Watching?
Having selected your downlink system, you need to understand who you are transmitting the video product to and where. Placing a media gateway in the network will allow you to push your video to command and control room, laptops, tablets and mobiles. The mission and the situational awareness that will be required will dictate the number of links that will be required for the various decision makers, ground teams and non-tactical observers.
About the author
Gavin Smillie served with the Royal Signals, British Army for 24 years travelling the globe and providing communication links over long distances for both radio and IT networks from cosy operations rooms to dusty and self-contained remote operation rooms, from single link operations to large scale operation rooms during peace and conflict. He has now worked within the commercial Communications arena for the last 10 years providing services and products for various Government, Military, Police and commercial markets.