Loran-C signal phase tracking apparatus

DETAILED DESCRIPTION With the above-described problems in mind, it is an object of the present invention to provide a phase tracking apparatus for a Loran-C signal which can track the phase of the received signal with great accuracy even when the S/N ratio of the reception signal is low and can improve the phase tracking accuracy when the S/N ratio is high.
This can be achieved by providing a phase tracking apparatus for a Loran-C signal comprising, as shown in FIG.
7, (a) first means for comparing the phase of the Loran-C pulse received from each transmitting station with that of a comparison signal; (b) second means for generating the comparison signal at a given integral multiple of the repetition rate of the Loran-C signal; (c) third means for measuring the signal-to-noise ratio of the received signal; (d) fourth means for correcting the timing at which the comparison signal is generated toward coincidence with the phase of the received Loran-C pulse when a given number of phase comparisons by the first means produce results of the same polarity; and (e) fifth means for adjusting at least one of the given integral multiple and the given number according to the measured signal-to-noise ratio.