Control link
The channel between the operator and the aircraft. It is present for most of a flight and has a recognisable structure in frequency and time.
Technology
A receiver,
not a radar.
Almost every small drone in operation talks to something. Those transmissions are what Falkonis listens for — and they are the one thing an operator cannot switch off without giving up control of the aircraft.
What there is to hear
A drone is a radio transmitter that happens to fly. Detection does not require seeing the airframe at all.
Video downlink
Usually wider, usually louder, and usually running whenever the operator is flying by camera. Often the easiest thing to hear first.
Telemetry and beacons
Short, regular transmissions that many airframes emit whether or not anyone is looking at them.
Deciding on the node
Receiving is the easy half. The work is in telling a control link apart from everything else on a crowded band — Wi-Fi, a neighbour's camera, a passing car — well enough that an alert is worth acting on. An early-warning system that cries wolf gets switched off within a week.
That processing happens on the node itself. Only a short alert leaves the device, which keeps the cellular data requirement small enough for the cheapest plan available and keeps the system useful where bandwidth is poor.
Why emitting is a liability
An active radar can be detected, located and targeted from well outside its own detection range. Its transmission is a beacon, and switching it on is a decision with consequences. A passive receiver has no such trade-off: there is nothing on the air for hostile radio reconnaissance to find, so the node can stay on permanently.
The same reasoning shapes the enclosure. A nest box on a tree is not worth a second look.
What passive does not solve
Being straight about the limits is part of the design. A drone flying a pre-programmed route with its radios off emits nothing to hear — that is the case the planned acoustic module exists for. Dense urban radio environments are harder than open country. And a single node gives you presence and rough proximity, not a track; direction comes from several nodes reporting together.
None of this is a reason to wait. Most of what is flying today is talking, and a few minutes of notice is worth more than a perfect picture that arrives too late.
See it in the product
Falkonis Nest is where all of this lands — the node, the power budget, the enclosure.