Beacon add-on subsystem for collision avoidance system
US4161729A · kind A · utility
Inventor
Key dates
| Filing date | Feb 9, 1978 |
| Grant date | Jul 17, 1979 |
| Priority date | — |
| Expiry date | Feb 9, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/933
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
By adding an indicator control panel to the cockpit and a small receiver-decoder unit between the transponder and the antenna of aircraft having a conventional air traffic control radar beacon system transponder, mid-air collision avoidance capability is obtained. The BACAS (Beacon Add-on Subsystem for Collision Avoidance System) receiver-decoder unit in an aircraft interrogates the associated ATC (Air Traffic Control) transponder to obtain and store the ATCRBS Mode C reply altitude information. The 1090 MHz transponder Mode C reply is given 5 MHz on-off amplitude modulation by the receiver-decoder unit and is radiated into space through the ATC antenna. Identical BASCAS hardware in aircraft within range sense the specially-modulated (5 MHz), Mode C reply and immediately act to trigger their respective ATC transponders into emitting Mode C replies with essentially the same special modulation characteristics except for a different modulation frequency (10 MHz). The replies emitted by other aircraft are sensed by the BASCAS receiver in the initial aircraft, and the Mode C altitude information from each aircraft is compared to the initially stored Mode C data. Any aircraft within a re…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.