Loran signal receiver

Abstract

A received signal containing a loran-C signal is periodically sampled. The sampled data values in two successive periods of the loran-C signal are stored in corresponding first and second period areas of a memory. The sampled data values for the next successive pair of periods of the loran-C signal are added to corresponding sampled data values stored in the memory. Such adding operation is repeated for a plurality of subsequent first and second periods of the loran-C signal. First and second groups each including a fixed number of totalled values are read from the first and second period areas, respectively, of the memory. The fixed number matches the number of pulses in each loran pulse group. The totalled values are read from memory addresses separated in coincidence with the separation of pulses in each loran pulse group. Each of the first and second groups of read values are processed in accordance with the known phase coding of each group of loran pulses. These processed values of the first and second groups are added and stored in corresponding memory address. The reading, processing, adding and storing steps are repeated until every possible combination of totalled values satisfying the separation criterion has been processed. Each of the loran pulse groups within each pair of successive loran-C signal periods is located according to which groups of values exactly match the known phase coding of each loran-C pulse group.