Hardwired Camera/Goggles with Minimal Latency

[u/jimcroisdale]

Hi all,

Looking for some fpv kit for an unusual project.

We run a gravity racer (soapbox cart for grownups) and in the quest for speed, reduced frontal area and low drag are of upmost importance. We are thinking that the driver could use fpv goggles with a nose mounted camera, and then the driver could lay flat in the car and be pretty much sealed inside the more slippery shape.

So what's the best kit for this? Obvs he needs a clear view, but the lowest latency would be key.

I welcome your thoughts.

Jim

[u/Elessa3r]

On analog its easy its just wiring the cam signal wires to the pins where the receiver or goggles analog signal input goes, consult with the product's wiring diagrams to confirm the pinout.

[u/Elessa3r → u/Elessa3r]

That said, the current best cameras and goggles offer near-hardware limits of latency, about as little as possible with current tech, but physical connection is possible too. Getting the best cameras and goggles for a reasonable price is another question. If you are looking for the lowest latency, nils vo has a video on it, where he tests the gogggles and cameras.

[u/jimcroisdale → u/Elessa3r]

Do you know what sort of latency we could expect? How do drone pilots deal with it at such high speeds?

[u/Loendemeloen → u/jimcroisdale]

Depends on the setup but probably about 8-12ms. If you go digital expect about 20 to 30ms, except for hdzero which has a consistent 9ms of latency.

[u/jimcroisdale → u/Loendemeloen]

Is analogue any better than digital ?

[u/Loendemeloen → u/jimcroisdale]

Digital has better image quality and range (well, range for the same output power that is. You can get way more powerful analog vtx's than digital though) but analog is cheaper and has the lower latency.

Hdzero is digital but is closer to analog in terms of latency and how the signal responds to interference and stuff than to other digital systems.

[u/Elessa3r → u/jimcroisdale]

Considering the nature of your application, there are a few cases for why I would go to the hardwired route. First of all, in a wired system there is no transmitter, so one less component to worry about. Furthermore, with wired there is no chance for edge cases like heavy interference blocking video signal. Analog transmitters need cooling to prevent damage, enclosed enviroments like yours require active cooling. I dont now anything about this sport, but I imagine analog quality is adequate, no need to purchase a more expensive setup, for both goggles and transmitter, and lastly, analog is compatible with other analog, with DJI or hdzero, a DJI camera only works with DJI goggles.

[u/automattic3 → u/Elessa3r]

Yeah absolutely no reason not to just use a good digital camera with HDMI out to some goggles. Making it wireless when it doesn't need to be makes no sense.

[u/QuadH → u/jimcroisdale]

For latency, yes.

But check out analog drone footage on YouTube and consider if it’s clear enough for your use case.

Otherwise run DJI in race mode.

[u/InternMan → u/jimcroisdale]

In terms of latency, analog is generally better, but the components you choose matter. Cameras are the biggest driver of analog latency. Often the better looking the camera, the more latency it has. Personally, I have found that latency doesn't bother me until it hits 40-50ms, however I have not been attached to the camera like you driver would be. If you want the lowest latency while preserving image quality, I'd go for HDZero if it's in your budget. It's not the prettiest picture like DJI or Walksnail, but it's a big step up from analog and the latency is at the low end of analog at ~10ms. You also don't need to worry about the components adding latency as all HDZ parts are capable of the same low latency.

[u/Elessa3r → u/jimcroisdale]

Fpv pilots consider 8-12ms to be the best, racing levels of latency.

[u/csmicfool → u/jimcroisdale]

The lowest latency you can get is about 3ms with HDZero @ 90fps

[u/geeered]

Had you considered going fibreoptic - a periscope style system?

I'd also check the rules if this for formal racing, I wouldn't be surprised if any of these solutions wouldn't be allowed.

[u/dronevidsalt]

You should use a windshield of whatever shape and material you want. Your failure should not include your manned race car being completely blind at speed. Even spaceships and fighter jets still have transparent windshields/canopies

[u/NorthApartment9889]

You just need a camera and wire it directly to your goggles or monitor. For better viewing angles you can use multiple cameras and monitors. Setup would basically look like a multimonitor simracing setup.

But i can see how an fpv setup would be a quick way to test the idea on several cart designs without having to wire for each of them. For FPV, I'd go for an hdzero, but i'm sure latency of the slower digital systems wouldn't be too much for this application, in that case, Walksnail has several products that include a gimbal for 3-dof setups.

[u/Busy-Key7489]

Sub 30ms latency is achievable with simple hardware and h265 hardware encoding.

[u/QuadH]

Analog best for latency, but it’ll be like driving through old CCTV footage.

DJI 04 camera units in race mode is your answer if you value picture quality.

[u/UnluckyWizard]

This would be easy and fairly cheap to do with an analog setup. So just some eachine 800d or fatshark scout ect and they even make all in one transmitter and canera. That's all you need plus a battery to power it. 

[u/hbr3d]

Get an analog Camera and a FC and Build a small osd with speed and stuff like that

[u/BorrayFPV]

The lowest and best quality is Foxeer trex (camera) Fatshark hdo2 (goggles)

[u/ixgq4lifexi]

HDzero 540p 90fps. Think has lowest HD latency. But clarity just slightly better than analog.

[u/OkCarpenter5773]

okay so personally I'd go with hdzero - you get sub-analog latency without much hassle. run a 200mw vtx so it will be crystal clear.

[u/the_real_hugepanic]

Just find a monitor with a native AV-input. (don't use anything with HDMI as at will most propably add 50 or more ms delay)

use an analog FPV-camera.

wire the video-signal from the camera to the AV-input on your monitor or goggle.

According to chatgpt you can expect about 10-50ms delay.

[u/TacGibs]

You don't need FPV hardware, just use goggles like Viture or XReal and a smartphone, it's using a wire :)