I’ve been testing FPV digital camera latency independently and I share the outcomes right here. Latency has an affect on the pilot’s response time and stick really feel, and it is without doubt one of the most necessary elements in selecting FPV cameras.
Other components of an FPV system may contribute to the general latency, for instance, video transmitter and receiver, but it surely appears to be insignificant in comparison with FPV digital camera lag. Here is my testing on this to show it: 5.8Ghz Analog VTX/VRX latency
The latency of an analog FPV digital camera is continually altering inside a sure vary. Manufacturers are inclined to brag about their cameras’ minimal latency, however the common latency are often a lot larger, and that why third get together testing like that is extraordinarily helpful.
Values in ms – milliseconds.
HD cameras as FPV digital camera:
*HD Cameras are measured throughout recording.
I see many reviewers use a digital timer on smartphone to measure the latency of a FPV digital camera or HD digital camera video out, which may be very unreliable in my view.
First of all, the show and digital camera each have comparatively low refresh charges, and they aren’t in sync both. For instance if all the things runs on 60fps, the consequence may have an error of as much as 16.7ms. This is a big error margin as a result of the bottom latency are right down to 4 or 5 ms in similar FPV cameras.
How it really works
My testing setup is straightforward, the FPV digital camera is linked on to a show through AV enter.
I put an LED in entrance of the digital camera, when is managed by an Arduino board. The show brightness will change because the LED activates and off. There is a photo-transistor (aka LDR – gentle dependant resistor) in entrance of the monitor to detect the brightness adjustments.
The time distinction between the turning on of the LED and alter of display brightness, can be the latency we measure.
The Arduino runs at 10KHz sampling fee, and I take 500 samples at random intervals in every check.
I like this setup as a result of it’s fully automated utilizing scripts.
The LED and LDR have delay as properly: LED takes time to activate and the LDR takes time to detect gentle. From my measurement, the delay of those parts is lower than 120us in whole, in comparison with the delay of our FPV cameras, that is negligible.
The show’s low refresh fee nevertheless, will probably be a extra important contributor of extra delay to our measurements. But since I’m taking a really massive variety of measurements at random intervals, the averaged consequence must be unaffected by the section shift. I can affirm the outcomes are constant and repeatable in my testing.
This testing is unquestionably helpful for evaluating relative measurements because the error would be the similar throughout all information samples.
My assumption was that the video format (NTSC/PAL) has an affect on the latency.
NTSC is 30fps whereas PAL is 25fps, however as a result of they’re interlaced (in each body, odd strains are drawn earlier than even strains), which supplies them an actual recent fee of 60fps (16.7ms) and 50fps (20ms) respectively. So in concept NTSC must be 3.3ms quicker than PAL.
I wish to confirm if NTSC is actually quicker than PAL, and the Eagle may be very helpful as I can simply change video encoding within the settings. So I examined the Eagle (CMOS) and Eagle 2 (CMOS) below PAL and NTSC.
Here’s what I discovered:
- With the Eagle, minimal latency decreases considerably with NTSC, whereas common latency exhibits average discount, however there’s little to no distinction in most latency
- The above discovering didn’t apply to the Eagle 2 although, the latency appears to be the identical in each NTSC and PAL
I checked with Runcam, they usually recommend the distinction in latency may very well be attributable to the digital camera algorithm, which could carry out barely higher with one video encoding format than the opposite. In this case, the Eagle 1 is quicker in NTSC whereas the Eagle 2 works barely higher in PAL. But video encoding itself doesn’t essential make a noticeable distinction in latency. Therefore to maintain issues constant, I’ll keep on with PAL every time attainable in my testing.
|Runcam Eagle 1||NTSC||45||17||32|
|Runcam Eagle 2||NTSC||33||17||26|
- 2017 May – article created
- 2021 May – up to date article with some extra cameras