As many people are having video range issues with the TBS Crossfire and 1.3GHz video we are working hard on a simple solution to solve this issue. There has been plenty of potential sources, so finding the true culprit was a bit of a search for a needle in the haystack. Right now, it looks like we found the problem.
Here is the reason why it does not work properly out of the box: Most receiver use a COMTECH (company) receiver module which is made to receive a wide range of frequencies. Due this wide range and other reasons there is no proper filtering on the antenna input, as we would expect from any common receiver module. Because of this the module receives both signals (video and crossfire) and mixes them into an intermediate frequency. The demodulator is not able to properly see the video signal due to blocking or AGC (Automatic Gain Control) that is going all over the place.
During our tests we could prove that the issue is on the VRX side. We also verified this by sending random Crossfire TX samples to a (very expensive) measurement lab and ensuring that there are no stray emissions also in a lab environment and not just our development environment.
The solution is simple: Because the frequencies are relatively close to each other the VRX needs better filtering. We are making notch filters and proceeding with further testing. We opened this thread to keep this issue and the discussions separated from the main thread.
RX: RMRC - 900MHz-1.3Ghz Receiver w/1258 with RMRC Comtech Tuner (Stock SAW)
TX: RMRC - 1.3GHz 1500mW Transmitte
Antennas TX and RX: SPW12 (1200-1360MHz)