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What are the characteristics of ZigBee compared with existing digital radio stations?
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A: The advantages are as follows:
(1) High reliability: Since the integration of ZigBee modules is much higher than that of general digital radio stations, there are fewer separate components, so the reliability is higher;
(2) Easy to use and safe: Because of the high integration, the ZigBee receiving module can be made smaller than the general digital radio, and the power consumption is low. The maximum emission current is much smaller than that of a CDMA mobile phone. Easy to integrate or directly placed in the device, not only easy to use, but also not easily damaged when carried outdoors.
(3) Strong anti-interference ability, good confidentiality and low bit error rate: ZigBee transceiver module uses 2.4G direct sequence spread spectrum technology, which is better than general FSK, ASK and frequency hopping digital radio. Anti-interference ability, and longer transmission distance;
(4) Free frequency band: ZigBee uses the free frequency band, and many frequency bands used by digital radio stations not only need to apply, but also need to pay a considerable frequency usage fee to the national committee every year;
(5) Low price: The price of the ZigBee digital transmission module is only a fraction of that of a digital radio station with similar functions.
10. What kind of wireless data transmission network does ZigBee have?
A: Simply put, ZigBee is a highly reliable wireless data transmission network similar to CDMA and GSM networks. The ZigBee data transmission module is similar to a mobile network base station. The communication distance is from standard 75 meters to several hundred meters, several kilometers, and supports wireless expansion.
ZigBee is a wireless data transmission network platform consisting of up to 65,000 wireless data transmission modules. It is very similar to the existing mobile communication CDMA network or GSM network. Each ZigBee network data transmission module is similar to a mobile network base station. Within the entire network, they can communicate with each other; the distance between each network node can range from the standard 75 meters to hundreds of meters or even kilometers. Different from the CDMA network or GSM network of mobile communication, the ZigBee network is mainly established for industrial field automation control data transmission. Therefore, it must be simple, easy to use, reliable in operation and low in price. The mobile communication network is mainly established for voice communication. The value of each base station is generally more than one million yuan, and each ZigBee "base station" is less than 1,000 yuan. Each ZigBee network node can not only be used as a monitoring object, for example, the sensors connected to it directly collect data and monitor data, and can also automatically transfer data data transmitted by other network nodes. In addition, each ZigBee network node (FFD) can also be wirelessly connected to multiple isolated child nodes (RFDs) that do not undertake network information relay tasks within the scope of their own signal coverage.
Each ZigBee network node (FFD and RFD) can support up to 31 sensors and controlled devices, and each sensor and controlled device can have 8 different interfaces. Digital and analog quantities can be acquired and transmitted.
11. What is the self-organizing network used by ZigBee?
A: A simple example can illustrate this problem. When a team of paratroopers airborne, each person holds a ZigBee network module terminal, and when they land on the ground, as long as they are within the communication range of the network module, they automatically pass each other. Looking for, you can quickly form an interconnected ZigBee network. They can't judge who is raining in advance, and because of the movement of people, the contact between them will change. Therefore, the module can also refresh the original network by re-finding the communication objects, determining the contact with each other. This is the self-organizing network.
12. Why does ZigBee technology use a self-organizing network to communicate?
A: Mesh network communication is actually multi-channel communication. In actual industrial sites, for various reasons, it is often impossible to ensure that every wireless channel can always be unblocked, just like a city street, possibly because of a car accident, road maintenance, etc. The traffic on a certain road is temporarily interrupted. At this time, because we have multiple channels, the vehicle (equivalent to our control data) can still reach the destination through other roads. This is very important for industrial site control.
13. Why do self-organizing networks use dynamic routing?
A: The so-called dynamic routing means that the path of data transmission in the network is not preset. Before the data is transmitted, all the paths available at the time of the network are searched, their positional relationship and distance are analyzed, and then the selected ones are selected. One path for data transfer. In our network management software, the path is selected using the "gradient method", that is, the channel closest to the path is selected for transmission. If it is not transmitted, another path is transmitted a little further, and so on. Until the data is delivered to the destination. At the actual industrial site, the predetermined transmission path may change at any time, or the path may be interrupted for various reasons, or it may be too busy to transmit in time. Dynamic routing combined with the mesh topology can solve this problem well, thus ensuring reliable data transmission.
14. What are the characteristics of ZigBee and existing communication mobile networks (GPRS, CDMA-1X)?
A: Its characteristics are:
(1) No network usage fee: The use of mobile network requires long-term payment of network usage fee, and is calculated according to the number of node terminals, and ZigBee does not have this fee;
(2) Low equipment investment: mobile terminal equipment needs to be purchased when using mobile network. The price of each terminal is about 1000 yuan. With ZigBee network, not only the ZigBee network node module (equivalent to base station) costs less than 1,000 yuan per renminbi. And, the main use of network sub-nodes (equivalent to mobile phones) is much lower;
(3) Communication is more reliable: Since the existing mobile network is mainly designed for mobile phone communication, although CDMA-1X and GPRS can perform data communication, it is found that not only the communication rate is much lower than the design rate, but also the data communication is reliable. Letters and continuity are not guaranteed in many cases. The ZigBee network is designed to control the transmission of data, so the control data transmission is quite guaranteed;
(4) High flexibility and low cost: Firstly, a ZigBee local automation control network is established by using ZigBee network nodes with different coverage distances, different functions, and low-cost wireless transceiver modules of other non-ZigBee systems. The Internet or mobile network is connected to a remote computer to achieve a low-cost, high-efficiency industrial automation telemetry remote control;
(5) Compared to the existing mobile communication network, although ZigBee is only a local area network, it can expand its coverage "infinitely" by providing sufficient data exports, and can be used with existing mobile networks, the Internet and Other communication networks are connected. And through these networks, many ZigBee LANs are connected to each other as a whole. Effectively solve the blind spot coverage problem of mobile networks: We know that existing mobile networks have blind spots in many places, especially in the wild, such as railways, highways, oil fields, mines, etc. The cost of adding a mobile base station or repeater is considerable. At this point, using ZigBee network for blind zone coverage is not only cost effective, but is often the only viable means.
15. How does ZigBee realize long-distance telemetry remote control?
A: The ZigBee network can also be connected to the Internet, GPRS network, CDMA1x network and other communication system lines through interface cards and other methods to achieve remote control. You can also connect two or more local ZigBee networks together over other networks.
16. What application areas does ZigBee technology have?
A: The goal of ZigBee technology is to target industrial, home automation, telemetry and remote control, such as lighting automation control, wireless data acquisition and monitoring of sensors, oilfield, power, mining and logistics management applications.
17. What industrial sites do ZigBee require for wireless data transmission?
A: Low power consumption, low data volume (250KPS), low cost, free ISM band (2.4G), high anti-interference performance, direct sequence spread spectrum communication (DSSS), high confidentiality (64-bit factory Numbering and support for AES-128 encryption), high integration and high reliability; automatic dynamic networking between node modules, using a topology including mesh network, using collision avoidance mechanism, information in The entire ZigBee network is transmitted by means of automatic routing, thereby ensuring the reliability of information transmission.
18. In what ways can ZigBee expand its application?
A: ZigBee applications: A wide range of applications for industrial automation, home automation, telemetry and remote control, automotive automation, agricultural automation and medical care, oilfield, power, mining and logistics management. Practical examples are as follows: lighting control, environmental control, automatic meter reading system, various curtain control, smoke sensor, medical monitoring system, large air conditioning system, built-in home control set-top box and universal remote control, heating control, home security, industrial and Building automation. In addition, it can also locate moving targets in a local area, such as vehicles in a city.
19. What are the conditions for short-range communication that can be considered for ZigBee technology?
A: Generally, ZigBee can be considered for short-range communication that meets one of the following conditions:
(1) There are many outlets that need data collection or monitoring;
(2) The amount of data required to be transmitted is not large, but the equipment cost is required to be low;
(3) Requires high reliability and high security of data transmission;
(4) The equipment is required to be small in size, and it is inconvenient to place a large rechargeable battery or power module;
(5) can be powered by battery;
(6) The terrain is complex, there are many monitoring points, and a large network coverage is required;
(7) Covering blind areas of existing mobile networks;
(8) A telemetry remote control system that has used an existing mobile network for low data transmission.
20. What is the application of ZigBee technology in China?
A: Although many people in China have begun to pay attention to the new technology of ZigBee, and many companies have begun to get involved in the development of ZigBee technology, however, considering that ZigBee itself is a new system integration technology, the development of application software must use the network. Transmission, RF technology and the underlying hardware and software control technology are combined, so it has certain technical difficulties for the initial development of enterprises. Due to various constraints, the large-scale commercial application of ZigBee technology will take time. However, it has already demonstrated extraordinary application value. It is believed that with the development and advancement of related technologies, it will definitely get more applications. However, we should also clearly understand that the wireless network based on ZigBee technology has just begun to develop, and its technology and application are still far from mature. Domestic enterprises should seize business opportunities, increase investment, and promote the whole industry. development of.
21. What is the mission of the ZigBee Alliance?
A: The ZigBee Alliance is a fast-growing, non-profit industry organization that includes internationally renowned semiconductor manufacturers, technology providers, technology integrators, and end users. The Alliance has developed a network application specification based on IEEE802.15.4 with high reliability, high cost performance and low power consumption.
22. What is the goal of the ZigBee Alliance?
A: The main goal of the ZigBee Alliance is to provide consumers with more flexible and easier-to-use electronic products by joining wireless network functions. ZigBee technology can be integrated into a wide range of electronic products for a wide range of applications in the civil, commercial, utility and industrial markets. It allows affiliates to use ZigBee, a standardized wireless network platform, to design products that are simple, reliable, inexpensive, and power-saving.
23. What is the focus of the ZigBee Alliance?
A: The focus is on developing the network, security and application software layers; providing different product coordination and interoperability test specifications; promoting the ZigBee brand around the world and striving for market attention; management technology development.
24. What is the work done by the ZigBee Alliance on the standard?
A: The development of the ZigBee standard: the physical layer, MAC layer and data link layer of IEEE802.15.4, the standard was released in May 2003. The development of the ZigBee network layer, encryption layer and application description layer has also made great progress. The V1.0 version has been released. Other application areas and related device descriptions will also be released. Since ZigBee is not only synonymous with 802.15.4, but the IEEE only deals with low-level MAC layers and physical layer protocols, the ZigBee Alliance standardizes its network layer protocols and APIs. The full protocol is used for 4K bytes of a base node that can be directly connected to one device or 32K bytes as a coordinator of a Hub or router. Each coordinator can connect up to 255 nodes, while several coordinators can form a network, and there is no limit to the number of route transfers. The ZigBee Alliance has also developed a security layer to ensure that such portable devices do not accidentally leak their identity, and that such long-distance transmissions over the network are not available to other nodes.
The ZigBee Alliance emphasizes device interoperability: Many ZigBee modules embedded in ZIRBee modules have ZigBee capabilities, and many products have reserved ZigBee interfaces for future upgrades. The development of various gateway products has also been further developed. The gateway products support the interconnection of existing facilities such as ZigBee system with home control network, intelligent building network and commercial network.
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