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What is the "Speed" of First Person View (FPV) on your Phone or Tablet?

LoudThunder

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I have watched a lot of videos where a drone pilot flies their drone miles out from their location using First Person View (FPV) by viewing the return image from the camera on their phone or tablet.

So, my question is; has anyone actually performed a "scientific test" of the video delay on the smaller drones, such as the Mini 2, the SE, the Mini. I've put scientific test in quotes because I'm hoping for more than, "it sure looks instantaneous…"

I intend to perform my own test when the weather is better and the wife is available to help perform the test.

What I intend to do is position the wife in our car about 1,000 feet away, facing me, with her cell phone, I'll position myself looking towards the car with the drone directly in front of me also facing the car. I will be able to visually see the car and I'll be able to see the car in the projected image from the drone.

Using my cell phone camera positioned so that the camera is filming the FPV on the tablet with the car visible in the background, I will then tell my wife to turn on the headlights using the cell phone.

My cell phone with record the image of my car's headlights turning on and will also record the image of the headlight turning on in the FPV and record if there is any delay in the image of the lights turning on.

I will also perform the same test but with the drone flown up to the car so that when the test is performed again, I will be able to see if the distance makes any difference in delay.

Yeah, I know the transmission is at the speed of light, but the distance (with the slightly weaker signal) might make a difference as the drone and radio receiver processes the weaker signal…

When I do this, I will post the video on the web site for all, But in the meantime, is anyone aware of a similar test having been performed before?
 
The drone and controllers have a latency specification, about 200mS. The latency between the controller and the "phone" adds to that number.
 
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The drone and controllers have a latency specification, about 200mS. The latency between the controller and the "phone" adds to that number.
And just to add to that for some perspective ... the DJI FPV quad system, end to end the Air unit video transmitter to the Goggles is 25-30ms in low latency mode with 120fps, 720P with a bitrate of 50,8Mbit.
 
Aren't latency figures included in a video that is occasionally cited in here? The video concerns the chips and transmission protocols of DJI drones from the Phantoms onwards, sorry I don't have a link at the moment.
 
Im not sure your “scientific” test is going to be any better than just someone saying “it sure looks instantaneous ”.
Isnt that all you will be able to say after your test?
😂😂
 
Page 28 of version 1.4 of the Mini 2 manual says this-

OcuSync 2.0 reduces latency to approx. 200 ms by improving the camera performance through the video decoding algorithm and the wireless link.

and it's dependent on the environment and the mobile device.
 
Once the signal is transmitted as a radio wave it will travel at the speed of light, the same as the light from the headlights. At 186,000 miles per second the time resolution on phones will not show elapsed time. Regardless of distance the measurable latency will be the sum of processing time from both ends of the transmission.
 
Thank you all who responded. My concern is if I am flying my drone well within visual view, but I've misjudged the distance of the drone from a tree and I suddenly see a branch in on my tablet screen, will I have a few seconds to stop or change direction or did I actually hit that branch 2-seconds ago. Once again, thank you for taking the time to respond.
 
...if I am flying my drone well within visual view, but I've misjudged the distance of the drone from a tree and I suddenly see a branch in on my tablet screen, will I have a few seconds to stop or change direction or did I actually hit that branch 2-seconds ago.
The control or live view signal delay will not be the issue in your scenario ... the issue will be the braking distance needed for the drone itself to stop or change direction. This is often misjudged where people come blasting back with full stick commands & crash into bushes just behind the pilot ... a lot of clips on YT showing that.
 
And just to add to that for some perspective ... the DJI FPV quad system, end to end the Air unit video transmitter to the Goggles is 25-30ms in low latency mode with 120fps, 720P with a bitrate of 50,8Mbit.
I hadn't seen that FPV spec - 28ms at 4kM is pretty darned good latency.
 
I hadn't seen that FPV spec - 28ms at 4kM is pretty darned good latency.
Yep, I'm always impressed by that the latency nearly never gets worse even at longer distances or behind obstacles when I fly my quads ... think it trades a maintained low latency against the bitrate, which will go lower when going out of LOS. And with their "Focus mode" which move in Mbits from the left/right 3:rd to the center 3:rd picture width anyway keeps the view enough detailed for continued flight.
 
Thank you all who responded. My concern is if I am flying my drone well within visual view, but I've misjudged the distance of the drone from a tree and I suddenly see a branch in on my tablet screen, will I have a few seconds to stop or change direction or did I actually hit that branch 2-seconds ago. Once again, thank you for taking the time to respond.
Latency will not be an issue for you in the scenario you put forward. Often the problem is judging distances when viewing through camera
 
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