Abstract: A method and apparatus for transmitting a message, in digital form, to or from a remote location. In a transmitter, a sequence of predetermined multiple-bit phase codes corresponding to the individual characters in the message phase modulate a carrier wave which also shifts frequency. At a receiving station, the various modulated carrier waves propagated through a dispersive medium constitute incoming signals with both frequency and range diversity. The receiver transforms the incoming signals into a sequence of quadrature component signals which it correlates with the multiple-bit phase code sequences to yield the digital representation of a transmitted message character at the receiving station.
Type:
Grant
Filed:
June 13, 1975
Date of Patent:
June 14, 1977
Assignee:
Lowell Technological Institute Research Foundation