Cars don't fall from sky
Usually it's hard to test complex system on a flying vehicle since it may crash or get lost because of some (even minor) bug. Hopefully we haven't crashed anything this year but we decided to test our system on a RC car until we ensure that there are no issues. Another advantage is that we have plenty of space on it so we do not worry about hardware dimensions and weight during tests.
First test showed us that entire system works pretty well and the only issue is video freezes on large distances. It was hard to analyze system performance without any info so we had to find a way to monitor all important parameters. After almost a month of development our real-time telemetry module was ready for tests. Currently it is capable of drawing real-time charts where such parameters as singal level/quality, current TX bitrate, camera bitrate, distance to home and relative latency for either RC commands and video stream are displayed. It also writes all monitored values into a log file so they can be analyzed after a flight.
After we got all required data it became possible to tune our solution for better performance. We've also implemented adaptive bitrate feature which dynamically decreases video bitrate once signal degradation is detected. You may see how everything works on the following video: