Sensor is a kind of detection device that can sense the measured information, and can convert the sensed information into electrical signals or other required forms of information output according to certain rules to meet the requirements of information transmission, processing, storage, display, recording and control. This is the first step to realize automatic detection and automatic control.
Both of them are Internet of Things technologies, but the difference is that sensor technology can deal with perceived items, while RFID only has identification, but has no processing ability.
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Question 2: What is the communication protocol between MCU and sensor? Need to read the user manual of the sensor, all kinds of sensors have their own communication methods.
Question 3: What kinds of sensor measurement methods are there? Shenzhen Modern Fang Hao Instrument Technology Co., Ltd. draws the following conclusions through the field measurement of sensors:
In the process of system inspection, various sensors are needed, and the measurement method and performance of sensors are the key factors for the successful completion of inspection tasks.
Direct measurement
Direct measurement means that when a sensing instrument is used for measurement, the reading of the instrument can directly represent the required result without any operation.
Indirect measurement
In some measurement occasions, direct measurement is impossible or inconvenient, which requires that when using sensors to measure, first measure several quantities that have a certain functional relationship with the measured physical quantity, and then substitute the measured values into the functional relationship, and get the required results through calculation. This method is called indirect measurement.
Combined measurement
When measuring with sensing instruments, if the measured physical quantity must be solved by simultaneous equations to get the final result, it is called combined measurement. In combination measurement, it is generally necessary to change the test conditions to obtain the data needed for a set of simultaneous equations.
Question 4: What are the basic classifications of MAC protocols in wireless sensor networks? At present, researchers have not adopted a unified MAC protocol classification method for different wireless sensor network applications, but they are generally divided into three types according to standards. One is contention-based MAC protocol: wireless channel random contention access (CSMA), in which nodes randomly use wireless channels when they need to send data. Typical MAC protocols such as CSMA need to pay attention to the problems of hiding terminals and exposing terminals. One is MAC layer protocol based on fixed allocation: wireless channel time division multiplexing contention-free access (TDMA), which assigns a fixed wireless channel usage period to each node, which can effectively avoid the interference between nodes. There is also a hybrid MAC protocol: TDMA/FDMA/CDMA (Time Division/Frequency Division/Code Division) for wireless channels, which realizes a conflict-free channel allocation strategy between nodes by mixing time division and frequency division or code division.
This is my graduation project. If you have more information, we can continue to communicate.
Question 5: What are the access control protocols for wireless sensor networks? HTTP protocol is required.
Sensor network is used to perceive the objective physical world and obtain the information of the physical world. The physical quantities in the objective world are varied and endless. Different sensor network applications care about different physical quantities, so there are various requirements for sensor application systems.
Wireless sensor network
Different applications have different requirements for sensor networks, and their hardware platforms, software systems and network protocols are inevitably very different. So it is impossible for sensor networks to have a unified communication protocol platform like the Internet. Although there are some problems in different sensor network applications, we are more concerned about the differences of sensor networks when developing sensor network applications. Only by making the system closer to the application can we make the most efficient target system. Studying sensor network technology for each specific application is a remarkable feature that sensor network design is different from traditional networks.
Wireless sensor networks have many different applications. In industry and commerce, it is used to monitor data, but if wired sensors are used, the cost is high and it is difficult to realize. Wireless sensors can be placed in barren areas for a long time to monitor environmental variables without charging and putting them back.
Question 6: What protocol does the wireless sensor network use? ZIGBEE protocol. The most suitable wireless communication technology for sensor networks. The corresponding protocol is ZIGBEE, and the implementation is ZIGBEE protocol stack. In addition, wireless communication technologies include WIFI, Bluetooth, GPRS and so on.
Question 7: What are the main types of inductive sensors, which can be divided into:
1, variable reluctance sensor-self-inductance
2. Differential transformer sensor-mutual inductance sensor
3. Eddy current sensor-Eddy current sensor
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Question: How many kinds of PM2.5 sensors are there? What is the difference? There are three principles for 5 PM2.5 monitoring:
gravimetric method
β -ray method
Light scattering method
For sensors, light scattering method is the real method to measure PM2.5 (other methods are too complicated).
There are two typical light scattering methods: laser and infrared light.
Infrared light: Japan's PPD42NS is nothing more than its originator. As early as 2003, Shen Rong Company registered the invention patent of light scattering method! Later, Sharp Company also invented GP2Y 10 10AU at a low price, and all of them achieved certain results.
Laser: laser is based on infrared light by projecting a stronger beam, that is, laser, plus a unique air duct with a "fan" design. Our model "AS0 1-T" is not difficult to understand the difference between strong beam and weak beam. The stronger the projection, the smaller the counting error. To put it bluntly, the technology has not reached perfection (because of its short life, the advantage of contrast infrared accuracy is not obvious), but it is not obvious in application.
Question 9: What are the basic classifications of routing protocols for wireless sensor networks? I know MODBUS RTU protocol and WSNXL protocol, but I don't know much about others. You can check it in Baidu Encyclopedia.
Question 10: What is the routing protocol of wireless sensor networks (1)? Traditional routing protocols rarely consider the energy consumption of nodes when choosing the optimal path. However, the energy of nodes in wireless sensor networks is limited, and prolonging the lifetime of the whole network has become an important goal in the design of routing protocols for sensor networks, so it is necessary to consider the energy consumption of nodes and the balanced use of network energy. (2) In order to save communication energy, wireless sensor networks based on local topology information usually adopt multi-hop communication mode, and the limited storage and calculation resources of nodes make it impossible for nodes to store a large amount of routing information and perform too complicated routing calculation. How to realize a simple and efficient routing mechanism is a basic problem in wireless sensor networks when nodes can only obtain local topology information and resources are limited. (3) Traditional data-centric routing protocols usually use addresses as the basis for node identification and routing, while a large number of nodes in wireless sensor networks are randomly deployed, which focus on the perceived data of the monitoring area, rather than the information obtained by specific nodes, and do not depend on the unique identification of the whole network. Sensor networks usually contain data streams from multiple sensor nodes to several sink nodes. According to the demand of perceived data, data communication mode and flow direction, a data-centric message forwarding path is formed. (4) The application environment of application-related sensor networks is different, and the data communication mode is also different. No routing mechanism is suitable for all applications, which reflects the application relevance of sensor networks. Designers need to design a specific routing mechanism for each specific application. In view of the above characteristics of routing mechanism in sensor networks, when designing routing mechanism according to specific applications, sensor networks need to meet certain routing mechanisms.