Receiving device and receiving method, and transmitting/receiving system

A receiving method comprising:

• a reception step of receiving a signal including a plurality of PPM symbols;
• a clock generation step of generating a clock for sampling with respect to the signal received in the reception step;
• an A/D conversion step of digital-converting the received signal on a basis of the sampling;
• a reference position detection step of detecting a leading position of the PPM symbols on a basis of data obtained in the A/D conversion step;
• and
• a clock error detection step of detecting a clock error,
• wherein the clock error detection step includes:
• a pulse position detection step of detecting a pulse position in the PPM symbols on a basis of data obtained in the reference position detection step and the A/D conversion step;
• a pulse position error calculation step of calculating a deviation of the pulse position on a basis of data obtained in the reference position detection step, the A/D conversion step, and the pulse position detection step;
• and
• a clock error calculation step of calculating the clock error on a basis of data obtained in the pulse position error calculation step, and
• wherein the receiving method varies a frequency of the clock generated in the clock generation step, on a basis of data obtained in the clock error calculation step.

A transmitting/receiving system comprising:

• a transmitter that transmits a signal including a plurality of PPM symbols;
• a receiver that receives the signal transmitted from the transmitter;
• a clock generator that generates a clock for sampling with respect to the signal received by the receiver;
• an A/D converter that digital-converts the received signal on a basis of the sampling;
• a reference position detector that detects a leading position of the PPM symbols on a basis of data from the A/D converter;
• a clock error detector that detects a clock error;
• a demodulator that, after the detection of the leading position of the PPM symbols, demodulates the PPM symbols on a basis of data from the reference position detector;
• an image display controller that controls a display image on a basis of data from the demodulator;
• and
• a display that displays the display image,
• wherein the clock error detector includes:
• a pulse position detector that detects a pulse position in the PPM symbols on a basis of data from the reference position detector and the A/D converter;
• a pulse position error calculator that calculates a deviation of the pulse position on a basis of data from the reference position detector, the A/D converter, and the pulse position detector;
• and
• a clock error calculator that calculates the clock error on a basis of data from the pulse position error calculator, and
• wherein the transmitting/receiving system varies a frequency of the clock generated by the clock generator, on a basis of data from the clock error calculator.