Apparatus and method for encoding and decoding data on tactical air navigation and distance measuring equipment signals

Apparatus for encoding data on a navigation signal, comprising:

• an encoder responsive to an input data bit of either a first or second logic level and repeating at a first BPS rate to generate an output data bit at the same logic level as the input data bit at a second BPS rate, where the second BPS rate exceeds the first BPS rate;
• a first pulse generator for generating a clock pulse, said clock pulse comprising a first pulse of a pulse pair;
• a second pulse generator responsive to the output data bit of said encoder and the clock pulse to generate a second pulse of the pulse pair, the second pulse having a first time delay between the first pulse for an input data bit at the first logic level and a second time delay between the first pulse for an input data bit at the second logic level;
• and
• means for combining the first pulse and the second pulse to produce a pulse pair navigation signal encoded with the input data bit.

Apparatus for encoding data on a navigation signal, comprising:

• a first pulse generator for generating a first pulse of a pulse pair;
• and
• a second pulse generator responsive to an input data bit of either a first logic level or a second logic level for generating a second pulse of the pulse pair, the second pulse having a first time delay between the first pulse for an input data bit at the first logic level and a second time delay between the first pulse for an input data bit at the second logic level;
• and
• means for combining the first pulse and the second pulse to produce a pulse pair navigation signal encoded with the input data bit.

Apparatus for decoding data encoded on a pulse pair of a navigation signal by pulse positioning, comprising:

• means responsive to the first pulse of a pulse pair navigation signal to generate a first logic pulse window occurring a predetermined time after input of the first pulse of the pulse pair and generating a second logic pulse window occurring a second time interval after input of the first pulse of the pulse pair, the second time interval exceeding the first time interval;
• first logic responsive to the pulse pair of the encoded navigation signal and the first logic pulse window to generate a first logic pulse when the time interval between the first pulse and the second pulse of the pulse pair equals a first time delay, the output of said first logic representing a first logic level of a data encoded on the pulse pair;
• second logic responsive to the pulse pair of the encoded navigation signal and the second logic pulse window to generate a second logic pulse when the time interval between the first pulse and the second pulse of the pulse pair equals a second time delay, the output of said second logic representing a second logic level of a data bit encoded on the pulse pair;
• and
• third logic responsive to the output of said first logic and said second logic for generating a signal at a first level for an encoded data bit of a pulse pair having a first logic level and for outputting a pulse at a second level for an encoded data bit of the pulse pair having a second logic level.

A data link system for transmitting and receiving data encoded on a navigation signal, comprising:

• a first pulse generator for generating a first pulse of a pulse pair;
• a second pulse generator responsive to an input data bit of either a first logic level or second logic level for generating a second pulse of the pulse pair, the second pulse having a first time delay between the first pulse for an input data bit at the first logic level and a second time delay between the first pulse for an input data bit at the second logic level;
• means for combining the first pulse and the second pulse to produce a pulse pair navigation signal encoded with the input data bit;
• a transmitter to transmit the encoded pulse pair;
• a receiver to receive the transmitted encoded pulse pair;
• and
• a decoder to decode the received encoded pulse pair to recover the data encoded thereon.