To avoid disruption of communication due to deviation of transmission and reception timing by correcting the deviation of transmission and reception timing with a communication partner.
A master unit 100 comprises: a piezoelectric element section 109 for detecting or generating an ultrasonic wave; a communication section 101 for communicating with the use of the ultrasonic wave; a storage section 105 for storing a table where slots having a certain time length are allocated in a time sequence and which is common with a slave unit 200; a distance acquisition section 112 for acquiring distance information about a distance with the slave unit 200; a distance calculation section 113 for calculating a distance from required time from time when the slave unit transmits a signal to time when the communication section 101 receives the signal; a slot timing monitoring section 108 for calculating the deviation of synchronous time between the master unit 100 and the slave unit 200 based on the acquired distance information and the calculated distance information; and a slot timing correction instructing section 110 for instructing correction of the deviated time.
Osamu Suzawa
Kazuhiko Miyasaka