Digital range computer systems for air navigation systems such as tacan

DETAILED DESCRIPTION What is claimed is: 1.
A computer system for calculating the range between two stations which are in radio communication with each other, said system comprising: a.
calculation means for producing an output having a value corresponding to the elapsed time between the transmission of a signal from a first of said stations to a second of said stations and the reception of a signal transmitted from said second station to said first station in reply to said first station transmitted signal, b.
control means for supplying information to said calculation means respecting time of the occurrence of said first station transmitted signal and the time of reception of said reply signal, and c.
means operated by said calculation means when said calculation means output equals an expected value for operating said control means to supply information simulating the information respecting the reception of reply signals to said claculation means whereby to maintain the operation of said calculation means on a continuing basis notwithstanding that said reply signals are missing.
2.
A computer system for calculating the range between two stations which are in radio communication with each other, a first of said stations transmitting successive signals to each of which the second of said stations transmits a reply signal, said system comprising a.
calculation means at said first station for producing an output having a value corresponding to the elapsed time between the transmission of a signal from said first station and the reception of said reply signal, b.
control means for supplying information to said claculation means respecting the times of the occurrence of each said successive first station transmitted signal and the reception of each said reply signal in response thereto, c.
means operated by said calculation means when said calculation means output corresponds in value to the elapsed time between a preceding signal from said first station and the reception of a reply signal in response thereto for supplying information to said control means respecting the time of occurrence of said last-named output, and d