I am sure we would all feel more comfortable if all flying machines were equipped with a inexpesive, light, low power traffic alerting system.
Is there any chance we could agree on such a system.
The logical thing would be ADS-B, implemented using the Mode S data channel.
This is what the rest of the universe is currently going for.
You start with a Mode S transponder (which nearly all of us will have to fit eventually
) and you connect it to your existing GPS (if you haven't got a GPS then forget any possibility of a low cost effective anti collision system). The transponder will then continuously radiate your GPS position. Anybody with a Mode S can do this right now - but not legally because such an installation is now
Enhanced Mode S which is an EASA Major Mod etc etc etc. On an N-reg you can do it - in the USA, a GTX330 etc will be radiating anything connected to it and nobody minds (the more the better).
The receiver for this data is very simple and needs just a little ADS-B aerial on the roof. The other plane has also got a GPS, of course, and a simple bit of software compares the two 3D positions. Much cheaper and much more accurate than the existing TCAS systems which for azimuth info use UHF direction finding principles whose azimuth accuracy will never be all that great.
The only issue is that I think ADS-B is meant to use
barometric altitude, which is going to be a lot less accurate (in absolute terms) than GPS altitude. But it would work OK.