Loran receiver-navigator

Apparatus for producing navigation information from the coded signals of existing network of radio transmitting stations each of which transmits a navigation signal in the form of a pulse group distinctively coded in accordance with the identity of that transmitting station, said apparatus comprising:

• receiver means for receiving said transmitted coded navigation signals,
• measuring means having search, settle, and track modes connected to said receiver means for making measurements at selected points on the waveform of each of said received coded signals and producing output signals representing the signal in-phase and quadrature amplitudes at said selected points on said signal waveform,
• said search mode involving the use of said measurements of said waveform to identify a group of said transmitting stations,
• said settle mode involving the use of said measurements of said waveform to locate a track point on the waveform for the received signal from each transmitting station of said station group,
• said track mode involving adjustment of the location of said track point on the waveform of said received signal from each transmitting station of said station group, to maintain said track point coincident with the point at which said quadrature amplitude is measured, only if said in-phase amplitude remains within a preselected tolerance between successive pulses of a pulse group,
• control means responsive to said output signals from said measuring means for selectively switching said measuring means to its search, settle, and track modes, and
• means rendered effective when said measuring means is in its track mode for generating from the output signals from said measuring means data demarcating the times of arrival of said coded signals for navigation purposes.

Apparatus for producing navigation information from the coded signals of an existing network of master and slave Loran transmitting stations each of which transmits a navigation signal in the form of a pulse group distinctively phase coded in accordance with the identity of that transmitting station, said apparatus comprising:

• receiver means for receiving said transmitted coded navigation signals,
• measuring means having search, settle, and track modes connected to said receiver means for making measurements at selected points on the waveform of each of said received coded signals and producing output signals representing the signal amplitude at said selected points on said signal waveform,
• said search mode involving the use of said measurements of said waveform to identify a group of Loran transmitting stations,
• said settle mode involving the use of said measurements of said waveform to locate a track point on the waveform of the received signal from each Loran transmitting station of said station group,
• said track mode involving the use of said measurements to adjust the location of said track point on the waveform of said received signal from each Loran transmitting station of said station group, to maintain said track point coincident with a preselected point on said waveform provided the signal magnitude at said preselected point remains within a predetermined tolerance,
• control means responsive to said output signals from said measuring means for selectively switching said measuring means to its search, settle, and track modes,
• means rendered effective when said measuring means is in its track mode for generating from the output signals from said measuring means data demarcating the times for navigation purposes,
• means responsive to the times of arrival demarcating output data from said generating means for establishing a station identity file listing in chronological order commencing with a selected reference Loran transmitting station the identity of the Loran transmitting stations from which coded signal have been received and tracked, and
• means for selecting any pair of Loran stations from said station identity file for generating data indicating the difference in times of arrival of said coded signals from said selected pair of Loran stations relative to the coded signals from said selected reference Loran station.