Sensor output signal and processing circuit problems2021

A sensor is a detection device that can feel the information being measured, and can transform the sensed information into electrical signals or other required forms of information output according to a certain rule, so as to satisfy the transmission, processing, storage, and display of information , Recording and control requirements.

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The output signal of the sensor is generally weak (mV, uV level), sometimes mixed with other signals (interference or carrier). Therefore, during the transmission process, the sensor output signal needs to be processed according to the specific characteristics of the sensor output signal and the requirements of the back-end system. Various forms of processing, such as impedance conversion, level conversion, shielding isolation, amplification, filtering, modulation, demodulation, A/D and D/A, etc., while also considering possible interference effects during transmission, such as Noise, temperature, humidity, magnetic field, etc., take certain measures, and the content of the sensor signal processing circuit should be determined according to the characteristics of the measured object and environmental conditions.

The main issues to be considered in the selection of the content of the sensor signal processing circuit include:

1. The output signal form of the sensor, whether it is an analog signal or a digital signal, voltage or current.

2. The sensor output circuit form, is it single-ended output or differential output

3. The output capacity of the sensor circuit, whether it is voltage or power, and the output impedance.

4. The characteristics of the sensor, such as linearity, signal-to-noise ratio, and resolution.

With the development of electronic technology and the application of micro-processing technology, many sensors have been equipped with some processing circuits (or equipped with special processing circuits), which greatly simplifies the technical difficulty of design and maintenance personnel. For example, the logic control circuit is integrated in the reflective photoelectric switch sensor; the output of the pressure sensor can be directly sent to the A/D after connecting to the dedicated interface processing circuit; the output of the photoelectric encoder sensor is a 5V pulse signal, which can be directly sent to the computer.