| 摘要 |
PURPOSE:To improve the accuracy of time difference measurement by utilizing sampling outputs of 3rd-5th cycles for one loran C signal when the S/N ratio of the loran C signal decreases. CONSTITUTION:The loran C signal received by a receiving antenna 1 is led to a sample circuit 3 and an S/N measuring means 5 through a receiving amplifier 2. The circuit 3 samples the 3rd cycle or 3rd-5th cycles of the loran C signal with a single pulse according to whether or not the S/N ratio of the loran C signal is sufficiently good or decreases and sends its output to a time difference display circuit 4 under the control of a sample control circuit 6. A circuit 5, on the other hand, measures the S/N ratio and sends it to the control circuit 6. The circuit 6 controls the circuit so as to sample the 3rd cycle or 3rd-5th cycles according to the S/N value. The circuit 4 measures and displays the time difference of the loran C signal between a main station and a slave station.
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