Background and Principles of Tacan Data Link

The integration of Tacan with very-high-frequency omnidirectional range (VOR) to provide one common air-navigation and air-traffic-control system requires, for full usefulness, a method of automatic air-surface communication. Such a method, called the Tacan data link, has been devised, and is being flight-tested. Using this data link, messages can be received and sent to each of 120 aircraft every 2.67 seconds. Such messages would consist of navigational, aircraft-status, and traffic-control information. The data link employs the Tacan Surface Beacon to carry both analog and digitallycoded messages, interpolating the coded pulse bursts, which last approximately 3 msec, 45 times every second. No additional transmitters or receivers are needed.