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Notes

OpenHD

DJI O3

HDZero

Walksnail

LTE (through internet)

URL to product

https://openhd.gitbook.io/open-hd/

https://www.dji.com/ca/o3-air-unit

Whoop Lite (W): https://www.hd-zero.com/product-page/hdzero-whoop-lite-vtx

Race V3 (R): https://www.hd-zero.com/product-page/hdzero-race-v3-vtx

https://caddxfpv.com/products/walksnail-avatar-vrx?variant=43697052418350

Already own all necessary hardware

Description

Is a software that uses wifi adapters to transmit data. Can be used on Raspberry Pi

Full commercial product designed for use with their own product lines (FPV goggles)

Known to produce lots of heat

HDZero is a brand, has many products available

Product comes in various combination of bundles

Using LTE to connect to the internet on the drone, then communicate via the internet with ZeroTier to create a local network.

Range

Higher is better

Depends on wifi adapter:

~3km for low power adapters, 75km record with 30dbi antenna

10km

7km (4-5 km is pretty clear, 7km gets a lot of static)

4km

Depends on strength of mobile signal

Size (WxLxH) [air]

Lower is better

Depends on wifi adapter

VTX: 32.5×30.5×14.5 mm

antenna: 85 mm

25.5 x 25.5mm M1.6 mounting

W: 32.4 x 32.5 x 4 mm (29x29mm inner) (25.5 x 25.5mm M2 mounting)

R: 32mm x 28mm x 5mm (20mm x 20mm M4 mounting)

33 x 33 x 9.5 mm

25.5 x 25.5 mm mounting

0 (already included on drone)

Mass [air]

Lower is better

Depends on wifi adapter

28g (transmitter) + 3g (antenna) = 31g

W: 4.5g (without shield)

R: 5.5g (without shield)

16g

0 (already included on drone)

Latency

Lower is better

On a Raspberry Pi, >100ms “glass to glass”

30ms @1080p/100fps

40ms @1080p/60fps

W: unknown

R: 14ms @540p/90fps

22ms average

Depends on server

ZeroTier Miami server (their closest one) from Waterloo campus: ~80ms

Transmitter (VTX) [air]

8812AU or 8812BU WiFi Card on a raspberry pi

Cannot purchase separately

W and R

https://caddxfpv.com/collections/walksnail-avatar-system/products/walksnail-avatar-hd-vtx-only

$100 on its own

Depends

Receiver (VRX) [ground]

8812AU or 8812BU WiFi Card and a laptop that boots into some specific OpenHD image.

DJI goggles 2, FPV goggles V2

Others are unknown

https://www.hd-zero.com/product-page/hdzero-vrx

Note: need to buy SMA antennas

Others are unknown

$220 on its own

Has a MicroSD card slot for DVR (supports up to 256GB micro SD cards)

Laptop is fine

Camera support

https://openhd.gitbook.io/open-hd/hardware/cameras

Should support a lot of them

Comes with a camera

Other camera support unknown

Does come with a camera if choose to buy a bundle (like $30 more)

Other camera support unknown

Does come with a camera if choose to buy a bundle

Other camera support unknown

Any should be fine

Operating frequency

all 2.4 and 5.8 GHz bands

2.400-2.4835 GHz (RX only)
5.725-5.850 GHz (RX and TX)

W: 5.8 GHz

R: 5.8 GHz

5.725-5.850 GHz

LTE (0.4-5.9 GHz)

Output

  • With DJI Goggles 2:
    4K@30/50/60/100/120fps
    2.7K@30/50/60/100/120fps
    1080p@30/50/60/100/120fps

  • With DJI FPV Goggles V2:
    4K@30/50/60/100/120fps
    2.7K@30/50/60/100/120fps
    1080p@30/50/60/100/120fps

H.265 Video format @ 50Mbps

W: 720p@60 fps

R: 540p@90fps, 720p@60fps, and 1080p@30fps

The VRX outputs HDMI video up to 720p@60fps

1080p@60fps, 720p@120fps, 720p@60fps

Transmitter uses H.265 Video format

VRX outputs HDMI video as well

Depends on the data transfer speed limit (10Mbps in Waterloo).

(But if 50Mbps can work for 4k@120fps on the DJI, 10Mbps should be enough, for ~1080p@96fps. This assumes using the same compression algorithm.)

On-board video capture

No

Yes

  • 20GB bulit-in storage in the air

  • microSD (up to 256 GB) in the air

No

Yes

  • microSD (up to 256 GB) on the ground

  • 8GB built-in storage in the air

No

Software Development effort

Lower is better

Medium:

A nice example with raspberry pi as ground: https://github.com/KenLagoni/OpenHD-LTE/blob/main/README.md

But if we really need less latency, a laptop is suggested:

Boot laptop into OpenHD image (pretty sure it’s Linux). We would want a fast USB stick since that’s the hard drive, and everything is saved on there.

Flash air raspberry pi with their OpenHD image (need to download the “ImageWriter”)

Then, the app displays the video whenever the air raspberry pi is on. Now, screen record this with OBS (pre-installed on the image). Start the OBS virtual camera, which should have the live stream now on it. Then, can use OpenCV on the OBS virtual camera.

*Note: this does require us to install all our software onto the “new OS”

*High:

Need to research how to get the video feed

*Note: the only way to get the video from what I’ve seen is through the goggles, which is very expensive. Even then, I don’t think it’s possible to get the video feed to process. It seems like it’s just for use with the goggles? They have a mobile app that can stream the video though

Low:

Can use video capture card which takes in HDMI and outputs it as USB, then OpenCV can read that in Python

(I think we do have an Elgato?)

Low:

Can use video capture card which takes in HDMI and outputs it as USB, then OpenCV can read that in Python

High

A pretty comprehensive tutorial: https://www.youtube.com/watch?v=EoB20ooWPJw

A little summary of what they do (I didn’t actually watch the video yet):

Compress the video before sending it, and then decompressing it, before finally processing it. Otherwise 10Mbps is only going to give 1080p@5fps.

Use Gstreamer to be able to send video packets and receive them.

Create a RTSP or UDP or HTTP stream server to send live video over ZeroTier

Cost (USD)

Lower is better

Depends on wifi adapters. Need one for air and one for ground.

Claimed to be <$100

$230 (No VRX/goggles)

W: $55

H: $70

VRX: $220 + antenna cost

Total: $275 - $290 without antenna

VRX: $220

$240-310 with everything included

$0, no cost, already own all hardware

Other Sources:

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