TCAS version 7

[Bandit60]

Can someone tell me the difference between version 7 on tcas (which is required for DRVSM) and the version previous to it.

Thanks for your responses

 

[CLCAP]

I think it's something about making the envelope for RA's and TA's a little bit smaller (i.e. so that you won't get the "traffic traffic" callout when someone is 900 feet above or below you above FL 290)

 

[Weasil]

http://www.arinc.com/tcas/

Several operational improvements have been made:

the logic will give far fewer Traffic Advisories in Reduced Vertical Separation Minimum (RVSM) airspace, and should virtually eliminate the problem of repeated TAs with a single aircraft that is currently experienced over the north atlantic track system.
A horizontal miss distance filter will reduce the number of occasions when an RA is triggered even though the aircraft will miss each other by a large horizontal distance. I.e. there will be fewer false alerts
The thresholds for triggering an RA in the case of level off manoeuvres (where the majority of spurious RAs occur) have been changed, and the associated manoeuvres changed to diminish the probability of making the aircraft cross in altitude when they don't need to.
Built in detection of suppression bus failure will reduce the number of times RAs are issued falsely with no other aircraft flying nearby.
The deviations required by the logic are less, thus diminishing the disturbance to ATC.
New aural alarms should avoid confusion by pilots
Improved vertical tracking to handle tracking of high performance aircraft (especially military).
These operational improvements are based on numerous technical improvements. In addition, there are new interference limiting algorithms that reduce the effect of TCAS II on the electromagnetic environment

 

[Lindy]

This the is the information I received at recurrent, courtesy of FSI.

TA Threshold: 850'
Corrective RA Threshold: 600'
Preventive RA Threshold: 700'

There is also the caveat that operations w/in 5 nm and 2000' of other a/c to climb and descend at 1000fpm.