Passive and active sensors
What is the difference between passive and active sensors? Professor Richard Mitchell explains more.
© University of Reading
A passive sensor is one which just ‘listens’ to what is happening. Examples include:
- A light sensor which detects if a light is shining on it
- An infra-red sensor which detects the temperature of an object
An active sensor is one which transmits a signal into the environment and then measures the response that comes back.
One example is an ultrasonic system:
- A pulse of ultrasound is emitted
- If an object is in the way, the pulse is reflected back
- The sensor detects it
- The time taken between emission and detection gives an indication of the distance of the object.
Hence an active sensor has an actuator and a sensor. In the next step you can find out more about this in Richard’s demonstration on echo location.
© University of Reading
Reach your personal and professional goals
Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.
Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.
