How It Works
Video Transmission over the LTE network
One of the commonly known problems of live video transmission over cellular networks is the lack of reliability to get a smooth uninterrupted video stream. Unlike many people think, this is not an inherent problem of the cellular connection but of the commonly used video codecs and video pipelines that are not optimized for links with transmission errors and fluctuating bandwidth. This usually results in frame drops or stalled video steams. We solved this problem by using our own proprietary fault-tolerant video pipeline that uses an auto-bandwidth adaptation mechanism to instantly change frame rate, resolution and compression parameters guaranteeing a snappy video stream even on very slow connections.
Another problem is that network carriers often only provide heavily firewalled 3G/4G connections. To overcome this, we use NAT Traversal / “hole punching” techniques to create a direct peer to peer connection, even if the link is firewalled. The Sky Drone FPV 2 unit and the groundstation find each other through our cloud based mediation-service which can also act as a fallback solution to relay traffic in the rare case that NAT Traversal / “hole punching” fails to establish a direct connection.
Low latency Video
Analog links often have a low latency. Digital solutions usually need buffering or use video codecs / video pipleines that are not built for low latency video or unreliable connections. Furthermore they are transferred on network protocols that are not suitable for real time video transfer. We use a custom video pipeline streamed via UDP to achieve low latency. For safety the current latency is always displayed in the groundstation app.
Telemetry and Command & Control Link
The Sky Drone FPV 2 system comes with a RS232/UART cable that can be connected to your flight controller. All data is relayed through a low latency peer-to-peer link to the Sky Drone FPV client software. The client software provides a TCP socket that you can connect to your Ground Station software. We have used this extensively with the MAVLink protocol and QGroundControl but any command & control link that interfaces with RS232/UART can be used.