TCAS IV
Wrongthong,
The azimuth 'issue' is only an issue when pilots try to do what they're expressly advised not to; i.e. manoeuvre in azimuth by interpreting the TCAS II display. TCAS II does not require to know where the other a/c is, only its altitude, distance from your aircraft and rate of change of that distance.
There will be no TCAS III.
My understanding is that TCAS IV will incorporate an air-to-air data link of the aircraft GPS position, so enabling much greater accuracy of azimuth presentation.
I'm a bit out of touch, having retired from flying 2 years ago, but I'm sure Collins or Honeywell would be happy to assist with your research.
rts