TADIL-A/Link 11 is a secure half-duplex TADIL radio link used by NATO that receives or transmits—but not both simultaneously—a sequential data exchange digital link. It exchanges digital information among airborne, land-based, and ship-board tactical data systems. It is the primary means to exchange data such as radar tracking information beyond line of sight. TADIL-A can be used on either high frequency (HF) or ultrahigh frequency (UHF). However, the U.S. Army uses only HF. Link 11 relies on a single platform to report positional information on sensor detections. This positional information can be amplified with additional data to qualify the identity of the detected track.