I am intending to build some UAV handheld controller like this one:
Test videos https://www.youtube.com/watch?v=HmxJ5Nw64z8 - in this video the user did not show antenna system but we can assume that they was using the directional one.
By looking at internal photos, I discovered that, look like it is using wifi router https://fccid.io/2AZBB-MK15TX/User-Manual/User-Manual-5485572
There are many of these kind of handheld controller in the market with incredible working distnace:
There are a lot of videos proving that the controllers are working correctly according to the advertising information. The controllers are widely used by UAV commnunity too. They are all similar at the common point of using module that similar to wife router (I checked by FCCID pages)
I wonder if we can pick the similar system combining with tuning software (openwrt) to reach that far?
That boards have some kind of Android OS. And they have audio-video.
On OpenWrt you mostly use device without audio/video because it's for embedded systems.
You are right, some of them are intergrated the RF and Android part. I still do not know how it can reach that far.
Just omnidirectional antenna: https://www.youtube.com/watch?v=r5LNfFYE7uA
Probably they're used some kind of radio amplifier?
If the distance is measured in KM, that is a radio transmitter, not wifi. Wifi cannot go at very long distances without a large directional antenna and an external power supply
Different wavelenght and transmission equipment.
Consumer drones use wifi for video feed, because they can add wifi for a few dollars, and if the whole drone costs like 200$ or less, you can't use expensive parts.
All serious RC and FBV drones use radio transmitters for both command signals and video signals.
Radio transmitters that can send video feed have long range, but are much more expensive than wifi.
This is a company that has Qualcomm chips working with OpenWrt https://doodlelabs.com/products/smart-radio/embedded-oem/
This is the origin where I believe in some ways, the long range wifi should be reasonable.
It may and may not have. I am not so sure at this point but there are a case that uses 5.8Ghz with <= 100mW radiation reaching up to 3Km!