System Architecture

This is pretty simple, we buy some OTS solution

Which OTS Solution? Idk….there’s some considerations we have to make:

Architecture considerations

Some things to consider:

1. Transmission frequency: 1.3GHz, 2.4GHz, 5.8 GHz

1.2/1.3GHz is probably the best when it comes to penetration and distance. Very cost prohibitive and should only be explored if we need to. Can be used with 900MHz crossfire/dragonlink as long as we use notch filters appropriately. Could impact GPS → need to mount antenna properly. Antennas are larger but this isn’t an issue if our drone is larger or equal to the size of vanny.

2.4GHz probably the most common? (also a controller freq tho).

5.8GHz more and more popular now (esp on digital). Can get a few km’s of range line-of-sight, but even a small tree/bush can kill the video…

2. Digital v Analog transmission

Digital tends to be higher quality but also higher latency. Digital systems tend to gain more noticeable latency as range increases, but less loss of signal quality. Analog systems tend to be more cross-compatible, while digital systems are a little bit more locked in.

3. FPV Goggles v Monitor

we use a monitor because that means changing from FPV to LOS is a lot simpler and safer. It also means multiple people can view the monitor, or we can split the output signal to multiple people (lot easier with monitors than fpv goggles).

We may end up using a receiver meant for goggles but plugged into a monitor. We will see.

4. Antenna tracking

Cheap ready-to-go- antenna tracking is available. GPS data is injected alongside video data and then decoded on the groundstation. Would use a seperate GPS from what we have, and could be OTS or we could make our own?

https://www.flyingtech.co.uk/fpv-camera-gimbals/arkbird-aat-auto-antenna-tracker-fpv-ground-station

5. Other Notes

• mounting of rx needs to be seperated from rc-link (two poles as far away as possible).

• Mounting of TX needs to be seperated from RC-Link

  • if we really wanted to, we could do some very basic antenna tracking with TX (same with the RC-Link I * guess * )

 Options

We consider 5 key components: camera, VTX module, Antennas, VRX module, and monitor. Not sure what the easiest way to pair them together would be…. Would it be better to just get the 1.3GHz setup? Or would we want to try 2.4/5.8 first? DJI Digital systems seem to be literally the best, if we can ever find them in stock and somehow get an hdmi output from them….

I think these are the viable tests that we would want to conduct:

• ground to ground LOS (walk from one end of an empty road to another).

  • Try this with both rx and tx ground level

  • Try this with RX / TX taped to the top of a broomstick or pole or smth (just a few metres off the ground)

• Air to ground LOS (TX on a balcony somewhere up high) - as high as we can get it, but consistent heights

  • walk (bike?) the RX away and see how bad latency might be?

• Air to ground with obstruction

  • Same task but this time try walking behind another building so it’s no longer LOS. Have walkie talkies or be on a phone call so you can evaluate what is happening.

 Action Items

Options

Uhhhhh Hopefully this is still understandable in about a week.

But also there’s a hell of a lot of antenna options available

1.2/1.3 GHz

2.4Ghz

• nvm couldn’t rly find anything it seems to be phased out now.

5.8

Digital Systems: THER ARE ONLY TWO

HDZero; https://www.getfpv.com/fpv/hd-fpv/hdzero-digital-hd-fpv-system/fat-shark-shark-byte-digital-hd-video-system.html

• https://www.getfpv.com/fpv/hd-fpv/hdzero-digital-hd-fpv-system/hdzero-vrx4-digital-hd-receiver-module.html

• https://www.getfpv.com/fpv/hd-fpv/hdzero-digital-hd-fpv-system/foxeer-digisight-v3-micro-digital-fpv-camera-starlight.html

• https://www.getfpv.com/fpv/hd-fpv/hdzero-digital-hd-fpv-system/hdzero-freestyle-digital-hd-video-transmitter.html

DJI System, uses goggles.

 References and documentation

• https://oscarliang.com/1-2ghz-fpv-guide/

• https://oscarliang.com/fpv-frequency/

• https://youtu.be/gNXeswKjmmQ

• https://oscarliang.com/make-diy-cloverleaf-antenna/

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