Aerospace HD-SDI & Video Standards
In light of the all new AD Aerospace HD-SDI camera (FV-0361), AD Aerospace’s Systems Engineer has written the following blog on video standards used for CCTV Video transmission within the aviation industry and also discusses the AD Aerospace HD-SDI offering.
Aerospace CCTV systems generally fall into the following categories:
The simplest set up. Analogue is the most widely adopted in the aerospace industry at the present time, with advantages of low latency and simple long-distance transmission.
Analogue can be transmitted either balanced or unbalanced. Balanced transmission is more robust against Electromagnetic interference (EMI), but signals usually require conversion at both ends. AD Aerospace offers cameras and monitors that support both balanced and unbalanced signals, enabling customers to easily integrate with other equipment.
In the industrial sector, the HD Analogue standard is gaining popularity, but this hasn’t found its way into the aerospace market.
IP Systems are gaining popularity within the aerospace industry, following the popularity that it has received in the commercial space. Key benefits of IP systems are as follows;
- As the aerospace industry uses Ethernet and IP technologies for non-critical data transfer between airborne systems, IP cameras can seamlessly integrate into this network with minimal additional wiring and weight.
- For new installations, IP allows more flexibility in network topologies, allowing system integrators to optimise for their chosen parameters.
- IP cameras compress the images prior to transmission. This edge-computing allows reduced data bandwidth, increases their scalability, and allows video storage LRU’s to reduce computing power, in-turn reducing system SWaP requirements.
- With next generation compression algorithms such as HEVC, it may be possible to transmit a 4K UHD video with acceptable quality under 10mb/s, allowing it to be used with older 10BaseT spoked networks, saving weight, cost, and replacement time.
- IP Systems are easily bi-directional, and configuration and control signals can easily be sent from other LRU’s to cameras without more supporting wires.
However, IP systems are not without their compromises;
- Compression and decompression algorithms take time to process, introducing latency into the system. Excessive latency between image capture and display can introduce significant workload on an operator. Latency can introduce uncertainty in positioning applications, increasing the risk of the manoeuvre.
- IP Cameras compression is affected by the video scene. Scenes where many objects are moving independently the video quality can suffer, or the required bandwidth can be substantially higher. This means the performance of IP cameras will be variable in scenes that involve precipitation.
The only standard listed here that has been developed specifically for Aerospace. ARINC 818 offers the low latency, high reliability that is needed for Avionics displays. This standard is meant for mission critical systems or where the safety of the aircraft is dependent on the video.
CCTV monitoring does not usually fall into this safety-critical category. As such AD Aerospace does not currently provide any products with ARINC 818 inputs or outputs.
While not widely adopted across the aerospace industry, HD-SDI offers the advantages of analogue for latency, while still allowing High Definition Video transmission. AD Aerospace are now offering an all new FV-0361 aerospace HD-SDI camera to the aviation industry.
Being a digital signal, the image can be reconstructed without amplifying noise. For situations where the video signal will be susceptible to EMI, HD-SDI can be made differential. AD manufactures the FV-0877 and FV-0477 as a matched pair of camera and video monitor which utilise this differential transmission.
Running at 1.5GHz HD SDI requires a higher specification cable harness that carries the video signal than analog. For AD’s new FV-0361, AD can supply cable harnesses up to 10m suitable for power and video signal connection to an FV-0591 Video server unit or 22D and size 8 contacts for other LRUs.