Automatic Independent Surveillance-Privacy

Automatic Independent Surveillance - Privacy (AIS-P) is a data packet protocol for the [http://www.collisionavoidance.org TailLight] system of aircraft Traffic Collision Avoidance, wherein a single Mode S 64 microsecond message is transmitted by an aircraft ATCRBS or Mode S transponder, and received by aircraft and Air Traffic Control on the ground. This is an [http://www.collisionavoidance.org/aispkit.jpgaugmentation] to aircraft transponders which states aircraft position and velocity in such a way as to minimize interference with any other avionics system, maximize the possible number of participating aircraft, while not relying on any equipment on the ground, and protecting aircraft from potential [http://www.airsport-corp.com/adsb2.htm attack] . AIS-P and ADS-B are competing protocols for aircraft based surveillance of traffic, a replacement technology for Mode S radar and TCAS.

AIS-P as an alternative to ADS-B

[http://www.collisionavoidance.org TailLight] implemented as a free addition inside General Aviation ATCRBS transponders, such as the [http://www.gtwn.net/~keith.peshak/BrochureT.pdf AT-155] , utilizes the AIS-P protocol to achieve all intended ADS-B advertised collision avoidance benefits in the terminal and en route airspace, but yet also has properties which no other aircraft collision avoidance system alternative provides: TailLight does not interfere with any other avionic systems, TailLight produces the maximum system capacity (up to 335,000 aircraft within line-of-sight of each other), and TailLight provides total interoperability with the other collision avoidance systems. TailLight provides these features without exposing the aircraft to potential [http://www.airsport-corp.com/adsb2.htm attack] , which is an important contemporary issue. TailLight doesn't cost the governments who allow its use any investment for infrastructure.

The AIS-P protocol is an alternative to the ADS-B and Mode S based TCAS protocols, and solves the problems of frequency congestion and increased danger. The AIS-P protocol does this by eliminating a requirement for multiple packet messages, or new longer packet definitions for ADS-B not established by international treaty, and by eliminating the 24 bit overhead for named identity in each packet of the message (required to tie multiple packets together into a message). Only one packet encodes latitude and longitude and altitude and direction and speed (full position and velocity), handles error detection and recovery, along with channel use arbitration, in the AIS-P protocol. This provides an unmatched capacity in comparison to all other collision avoidance alternatives, because of the elimination of verbosity unnecessary to collision avoidance purposes.

All technologies have limitations in addition to advantages. There are identified deficiencies to the AIS-P protocol - it is worthless for purposes of billing and targeting. AIS-P does not consider those requirements as necessary for collision avoidance, and does not sacrifice capacity to offer them. Additionally, one of the requirements satisfied by the AIS-P protocol is that a missile with an ADS-B type target homer aimed at the unnamed aircraft alone in the sky would miss.

References

ADS-B