JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III BASICS OF SENSORS TECHNOLOGY Previous Question Paper (February/March - 2022 - R18)

A measurement system acts as an interface between the physical quantity (measurand) and the observer. The general input-output configuration consists of three primary stages: the detector-transducer stage, the signal conditioning stage, and the output display or data presentation stage.

The detector-transducer stage senses the physical variable and converts it into a usable electrical signal. The signal conditioning stage modifies this signal through processes such as amplification, filtering, or analog-to-digital conversion to make it suitable for processing. Finally, the output stage presents the data through indicators, recorders, or computer interfaces for interpretation.

Block diagram flow: Physical Input (Measurand) -> Detector-Transducer -> Signal Conditioning -> Data Presentation -> Output/Observer.

A sensor is a device that detects changes in physical, chemical, or biological quantities and produces an output, typically in the form of an electrical signal, that represents the measured quantity.

Sensors are classified based on the following criteria:

• Active vs. Passive: Active sensors require an external power source (e.g., LVDT), while passive sensors generate their own electrical signal from the stimulus (e.g., Thermocouple).
• Analog vs. Digital: Analog sensors produce a continuous signal (e.g., Potentiometer), whereas digital sensors produce discrete output signals (e.g., Digital Encoder).
• Contact vs. Non-contact: Contact sensors require physical contact with the measurand (e.g., RTD), while non-contact sensors operate remotely (e.g., Infrared sensor).

Applications include: Temperature sensors in industrial process control, Proximity sensors in automation and robotics, Pressure sensors in automotive systems, and Optical sensors in consumer electronics and communication systems.