Low Cost Hyperbolic Airport Surveillance System

As multilateration systems have proved to be reliable and cost efficient alternatives to radar tracking, the authors attempted to design a multilateration surveillance solution for Aurel Vlaicu International Airport Bucharest, capable of accurate tracking of both aircraft and ground vehicles. Although the airport is not large, the number of ground vehicles is significant, and in order to be received by a classic multilateration receiver network, they need to be fitted with Mode S transponders. Also, the receiver network requires rather expensive digital clocks, for an adequate measurement of phase. In the stage of value engineering of the project, the authors managed to change significantly the system, as to become a truly low cost one. The idea keeps the hyperbolic positioning method, but based on frequency drift (similar to radar altimeter technology), and not on phase, as in a classic multilateration system. The ground vehicles require an inexpensive low-power transceiver, which is active regardless of the status of the vehicle: in use, turned off, parked etc. This feature (provided by an autonomous battery) is useful as a safety net against the risk of vehicle driver error or misconduct. Whereas pilots are generally trained and reliable, vehicle drivers need a tracking system out of their possibility of intervention. As for the position of the aircraft, the authors propose the use of an inexpensive ADS/B receiver. For the moment, this technology is not yet mature (some aircraft are not fitted with ADS/B, some are transmitting the position taken from the IRS as the only source, indicating inaccurate positions). In the future though, one can expect consistent progress of ADS/B technology, thus improving the practical value of this system. The system provides a simulated radar image on any PC, being easily accessible not only to the TWR and GND air traffic services, but also to the airport management, airport service providers, airport security, operators and other authorized parties. The authors trust that a low cost hyperbolic airport surveillance system could be an interesting alternative for many not so large airports, with occurrences of low visibility, with a modest investment budget.