MOBILE TERMINAL, WEARABLE TERMINAL, SOUND WAVE RANGING SYSTEM, AND SOUND WAVE RANGING METHOD

摘要

PROBLEM TO BE SOLVED: To solve the problem that in the case of sound wave ranging using two mobile terminals, clock synchronization and calibration are necessary, which takes time and labor.SOLUTION: A reproducing unit 130 reproduces a first ranging signal. A recording unit 140 records the first ranging signal and a second ranging signal output from another mobile terminal. A time difference measuring unit 170 measures first difference between record starting time of the first ranging signal and record starting time of the second ranging signal. A communication unit 180 receives second difference between record starting time of the first ranging signal and record starting time of the second ranging signal measured by the other mobile terminal from the other mobile terminal. A distance calculation unit 190 calculates distance to the other mobile terminal by multiplying a subtraction result between the first difference and the second difference by sound speed.SELECTED DRAWING: Figure 5