Obstacle detection sensor

A distance measurement device comprising:

• an oscillator configured to oscillate a carrier wave;
• a pulse generator configured to output a unique code as a pulse signal;
• a modulator configured to modulate the carrier wave and output a modulated wave corresponding to the pulse signal;
• a piezoelectric element configured to oscillate and receive an ultrasonic wave corresponding to the modulated wave;
• and
• a controller configured to calculate a distance based on the code obtained by demodulating a reflected wave of the ultrasonic wave received by the piezoelectric element,
• wherein the modulator modulates the carrier wave using a plurality of modulation schemes at the same time.

A distance measurement device comprising:

• an oscillator configured to oscillate a carrier wave;
• a modulator configured to output a modulated wave obtained by adding an identification signal to the carrier wave by a predetermined scheme;
• an oscillation element configured to oscillate an ultrasonic wave corresponding to the modulated wave;
• a receiving element configured to receive the ultrasonic wave;
• a demodulation unit configured to demodulate the ultrasonic wave received by the receiving element;
• and
• a controller configured to determine a scheme of the demodulated ultrasonic wave,
• wherein the controller causes the receiving element to receive the ultrasonic wave beforehand when the modulator outputs the modulated wave, causes the demodulation unit to demodulate the received ultrasonic wave to acquire a demodulated signal, and determines a scheme of the demodulated signal to output information about the scheme to the modulator, and
• the modulator adds the identification signal to the carrier wave by a scheme different from the scheme of the demodulated signal based on the information and outputs the modulated wave.