Uncrewed Systems Technology 046

39 better suited for open source platforms, where having full control over the system is desirable to achieve the desired latency. In this case, the support is split in two: a kernel driver, which is provided by a Linux Hantro driver, and a user component that can be provided by frameworks such as GStreamer and FFMPEG. This has been used for H.265. Unlike the currently supported codecs (JPEG, MPEG-2, VP8 and H.264), it doesn’t rely on the G1 hardware block but on the second video processor unit, the G2. For this first step, the driver supports the basic H.265 features up to level 5.1. Enhanced features such as 10-bit depth per sample with 4:2:0 chroma sampling, scaling or tile decoding could be added later. Another possible development is to use compressed buffers to limit the memory bandwidth consumption. Then there is the transmission. Dynamic encoding can adjust the signal level of the RF link by using tables of reference data to adjust the frame rate, bit rate and resolution dynamically. This ensures some video arrives at the right time regardless of the flying conditions and the radio link. For example, another technology for low-latency encoding is adaptive encoding optimised across the available network bandwidth for remote control of a UGV or UAV in almost real time (a latency of 400 ms) from a remote location. When using the internet there are other considerations. With standard routing, the IP packets can be sent via many different routes, waiting at the destination for all the packets to arrive and then making sure they are in the right order. That can create a highly variable latency. However, virtual private networks (VPNs) can be set up with dedicated servers at each end of the link that can send the packets over pre-established routes. That provides much greater Video systems | Focus Outside broadcasts For remote control of an uncrewed system, low latency is vital. The latency consists of elements including the time taken to encode the video Uncrewed Systems Technology | October/November 2022