Timing detection method, communication system and receiving apparatus

1 . A timing detection method comprising:

intermittently transmitting, by a transmission apparatus, a physical frame of a transmitted signal;

calculating, by a receiving apparatus, a correlation between a received signal and each of correlation sequences subjected to Doppler shift of a plurality of types of shift amounts; and

determining, by the receiving apparatus, that the physical frame has been received in a case where any one of calculation results exceeds a threshold,

wherein each of the plurality of types of shift amounts is any value obtained by multiplying a reciprocal of a product of a sequence length of a correlation sequence and a symbol rate of the physical frame by an integer.

2 . A timing detection method comprising:

calculating a correlation between a received signal having been transmitted from a transmission apparatus that intermittently transmits a physical frame of a transmitted signal and each of correlation sequences subjected to Doppler shift of a plurality of types of shift amounts; and

determining that the physical frame has been received in a case where any one of calculation results exceeds a threshold,

wherein each of the plurality of types of shift amounts is any value obtained by multiplying a reciprocal of a product of a sequence length of a correlation sequence and a symbol rate of the physical frame by an integer.

3 . A communication system comprising a transmission apparatus and a receiving apparatus,

wherein the transmission apparatus intermittently transmits a physical frame of transmitted signal, and

the receiving apparatus includes:

a correlation calculation circuitry that calculates a correlation between a received signal and each of correlation sequences subjected to Doppler shift of a plurality of types of shift amounts; and

a determination circuitry that determines that the physical frame has been received in a case where any one of calculation results obtained by the correlation calculation circuitry exceeds a threshold,

wherein each of the plurality of types of shift amounts is any value obtained by multiplying a reciprocal of a product of a sequence length of a correlation sequence and a symbol rate of the physical frame by an integer.

4 . A receiving apparatus comprising:

a correlation calculation circuitry that calculates a correlation between a received signal having been transmitted from a transmission apparatus that intermittently transmits a physical frame of a transmitted signal and each of correlation sequences subjected to Doppler shift of a plurality of types of shift amounts; and

a determination circuitry that determines that the physical frame has been received in a case where any one of calculation results obtained by the correlation calculation circuitry exceeds a threshold,

wherein each of the plurality of types of shift amounts is any value obtained by multiplying a reciprocal of a product of a sequence length of a correlation sequence and a symbol rate of the physical frame by an integer.

5 . The receiving apparatus according to claim 4 ,

wherein the plurality of types of shift amounts are values shifted by a predetermined Doppler frequency, and

a ratio of signal power and noise power of a received signal calculated using a correlation sequence of the predetermined Doppler frequency matches a ratio of signal power and noise power of a received signal at a detection threshold calculated using a correlation sequence of a reference shift amount in a case where one of the plurality of types of shift amounts is regarded as the reference shift amount.

6 . The receiving apparatus according to claim 4 ,

wherein the received signal has been transmitted underwater.