Method and apparatus for noise control in ultrasonic sensors

A method of operating an active ultrasonic occupancy sensor comprising the steps of:

• providing an ultrasonic occupancy sensor comprising:
• an ultrasonic transmitter;
• an ultrasonic receiver;
• a power supply operably connected to the ultrasonic transmitter that includes a main power supply and produces a main output power and an adjustable voltage regulator that produces regulated, controlled output power, the power supply also includes a fixed voltage regulator which receives the main output power, transforms the main power into intermediate power and applies the intermediate power to the adjustable voltage regulator;
• and
• a controller operably connected to the ultrasonic transmitter, the ultrasonic receiver and the power supply;
• processing a received ultrasonic signal to generate a first signal representing an ultrasonic voltage envelope;
• processing the first signal to generate an ultrasonic peak noise signal;
• and
• controlling the regulated controlled output power of the adjustable voltage regulator according to sensitivity input of the sensor and an ultrasonic peak noise signal.