The Zaon PCAS portable collision avoidance system is a very simple box which is considered as carry on – therefore requires no certification. Aircraft carry transponders which are interrogated by ground based radar and respond with a signal which may include height information. This is used to plot the aircraft on an ATC screen.
The Zaon device listens to the responses from nearby aircraft and estimates their distance from you based on signal strength. If the aircraft is transmitting height it will also show you that and if it is climbing or descending.
It prioritises the received aircraft and gives you a warning. It does not tell you in which direction it is – but its enough to add a level of safety.
The main PCB is split into 3 distinct parts. On the left there is the power supply, its a buck-boost circuit which provides 3.3 from batteries that may below 3v. An external connector uses the same power supply and can operate up to 28V.
On the right there is a radio front end which operates on 1090Mhz, with basic decoding of mode C signals.
In the middle there is a microcontroller that does all of the processing and drives the display. My guess from the label P16F877 is that its probably a Microchip Pic 16F177 controller. I’m familiar with these from my past, they are a 40 pin controller with USB connectivity – you can see it does have 40 pins. These are still in production in 2022.
The only other point worthy of note is the display which is insanely bright. A broadcom device found here.
Sadly, Zaon no longer seems to exist but Garmin make an XRX version which gives quadrant directional information. But to be honest you can achieve the same today with a Raspberry PI and a software defined radio – which also allows you to decode ADSB.