There is an easy way to measure latency with your system. Place a stopwatch (or stopwatch app on your phone) in view of your FPV camera. Start the stopwatch. Then, take a picture of both the stopwatch and your FPV display. Subtract the FPV display time from the stopwatch display and you'll have your latency. It can be a little tricky to get everything lined up to get a good photo, especially with the el-cheapo FPV goggles I have.
Human reaction time is ~ 0.1 seconds or 100ms. Hopefully your measured latency is less than that!
I measured the latency of my FPV system:
- GoPro Silver 4, with video output cable (cable purchased from Amazon)
- Quanum Complete FPV bundle transmitter, receiver, and DIY goggles
|Test #1: Phone stopwatch on the left, FPV goggles on the right|
Test #2: 27.03 - 26.96 = 0.06 seconds = 60 ms
I'm pretty happy with the "measured" latency of the system- it seems like a GoPro4 with a real time video output cable, and the Quanum FPV bundle yields a latency of 60-70 ms.