Modern communication technology is moving towards the core technology of network packetization and narrowband access technology wireless. In the field of wireless access, early adopters were circuit-based transmission methods and packet transmission technologies. Recently, Bluetooth special interest group SIG, consisting of five companies including Ericsson, Intel, Nokia, Toshiba, and IBM, has jointly launched the Bluetooth initiative (Bluetooth). Bluetooth is becoming a rookie in the data transmission field because of its small size, low cost, and strong penetrability. In the automatic fire alarm system, Bluetooth technology is used for wireless transmission, which has advantages that other technologies cannot match.
A brief introduction of Bluetooth technology
"Bluetooth" technology is an open standard for a universal wireless signal transmission interface and its control software, and is a technical specification for a short-range wireless connection device having a low form factor. Its purpose is to make the network ubiquitous, that is, to use wireless technology to replace the existing network connection, so that the hardware produced by different manufacturers can have the possibility of interactive information and cross-operation in a close range in the case of wireless connection. It is based on a low-cost, short-range wireless connection that provides a common interface for existing digital networks and peripherals to form a special connected device group for a long-distance fixed network, and uses radio waves to transmit between two electronic devices. Data or other digital content.
The Bluetooth system consists of four functional units: wireless unit, link control unit, link management, and software function. The core technology of the Bluetooth system consists of a microchip set consisting of basebands and RF chips that are both 9mm x 9mm in size. The baseband chip uses a built-in wireless communication protocol to perform simple digital information processing, allowing different Bluetooth products to exchange data; RF chips are responsible for transmitting signals. Bluetooth technology emphasizes small size, low power and low price, and supports point-to-point and point-to-multipoint connections. We usually call all devices connected together via Bluetooth as a piconet. Several piconets can be connected together. Each piconet is identified by the frequency hopping sequence. All users of the same piconet synchronize with this hopping sequence. The topology can be described as a "multiple piconet" architecture in which the full-duplex data rate can exceed 6 Mb/s with 10 fully loaded independent piconets.
Modern communication technology is moving towards the core technology of network packetization and narrowband access technology wireless. In the field of wireless access, early adopters were circuit-based transmission methods and packet transmission technologies. Recently, Bluetooth special interest group SIG, consisting of five companies including Ericsson, Intel, Nokia, Toshiba, and IBM, has jointly launched the Bluetooth initiative (Bluetooth). Bluetooth is becoming a rookie in the data transmission field because of its small size, low cost, and strong penetrability. In the automatic fire alarm system, Bluetooth technology is used for wireless transmission, which has advantages that other technologies cannot match.
Other Bluetooth features:
1. Bluetooth works in the internationally open 2.4 GHz ISM (industrial, scientific, medical) frequency band. In this frequency band, users do not need to apply for the use of frequency to a special management agency.
2. Adopt frequency hopping spread spectrum technology to divide 79 frequency points from 2.4 GHz to 2.4835 GHz. The frequency hopping determined by the master unit of piconet is a random sequence of 1600 hops per second, making the wireless link itself possess Higher security and anti-jamming capability
3, transmission distance. The current working distance is within 10 meters and can reach 100 meters after increasing RF power. This range of work enables Bluetooth to guarantee a high data transmission rate while reducing the interference of other electronic products and radio technologies, which is beneficial to the security of the system.
4. The modulation method adopts GFSK, BT=0.5, positive frequency deviation means 1 and negative frequency deviation means 0;
5, using time division multiplexing multiple access technology, each Bluetooth device in its own time slot in the form of data packets to send data in time slots, can effectively avoid the wireless communication "collide" and "hidden terminal" and other issues;
6, support for synchronous directional connection (SCO) and asynchronous connectionless (ACL) two connection types, both connection types use TDD (time division duplex transmission scheme) to achieve full-duplex transmission;
7. The baseband controller uses three types of error correction schemes to achieve error-free data transmission;
8. The air interface is based on an antenna level of 0 dBm and complies with the FCC (United States Federal Communications Commission) standards relating to the 0 dBm ISM band;
9, in line with Bluetooth 1.0b version of the specification: software version is re. 1.08, hardware version is DIG8043390.
A brief introduction of Bluetooth technology
"Bluetooth" technology is an open standard for a universal wireless signal transmission interface and its control software, and is a technical specification for a short-range wireless connection device having a low form factor. Its purpose is to make the network ubiquitous, that is, to use wireless technology to replace the existing network connection, so that the hardware produced by different manufacturers can have the possibility of interactive information and cross-operation in a close range in the case of wireless connection. It is based on a low-cost, short-range wireless connection that provides a common interface for existing digital networks and peripherals to form a special connected device group for a long-distance fixed network, and uses radio waves to transmit between two electronic devices. Data or other digital content.
The Bluetooth system consists of four functional units: wireless unit, link control unit, link management, and software function. The core technology of the Bluetooth system consists of a microchip set consisting of basebands and RF chips that are both 9mm x 9mm in size. The baseband chip uses a built-in wireless communication protocol to perform simple digital information processing, allowing different Bluetooth products to exchange data; RF chips are responsible for transmitting signals. Bluetooth technology emphasizes small size, low power and low price, and supports point-to-point and point-to-multipoint connections. We usually call all devices connected together via Bluetooth as a piconet. Several piconets can be connected together. Each piconet is identified by the frequency hopping sequence. All users of the same piconet synchronize with this hopping sequence. The topology can be described as a "multiple piconet" architecture in which the full-duplex data rate can exceed 6 Mb/s with 10 fully loaded independent piconets.
Modern communication technology is moving towards the core technology of network packetization and narrowband access technology wireless. In the field of wireless access, early adopters were circuit-based transmission methods and packet transmission technologies. Recently, Bluetooth special interest group SIG, consisting of five companies including Ericsson, Intel, Nokia, Toshiba, and IBM, has jointly launched the Bluetooth initiative (Bluetooth). Bluetooth is becoming a rookie in the data transmission field because of its small size, low cost, and strong penetrability. In the automatic fire alarm system, Bluetooth technology is used for wireless transmission, which has advantages that other technologies cannot match.
Other Bluetooth features:
1. Bluetooth works in the internationally open 2.4 GHz ISM (industrial, scientific, medical) frequency band. In this frequency band, users do not need to apply for the use of frequency to a special management agency.
2. Adopt frequency hopping spread spectrum technology to divide 79 frequency points from 2.4 GHz to 2.4835 GHz. The frequency hopping determined by the master unit of piconet is a random sequence of 1600 hops per second, making the wireless link itself possess Higher security and anti-jamming capability
3, transmission distance. The current working distance is within 10 meters and can reach 100 meters after increasing RF power. This range of work enables Bluetooth to guarantee a high data transmission rate while reducing the interference of other electronic products and radio technologies, which is beneficial to the security of the system.
4. The modulation method adopts GFSK, BT=0.5, positive frequency deviation means 1 and negative frequency deviation means 0;
5, using time division multiplexing multiple access technology, each Bluetooth device in its own time slot in the form of data packets to send data in time slots, can effectively avoid the wireless communication "collide" and "hidden terminal" and other issues;
6, support for synchronous directional connection (SCO) and asynchronous connectionless (ACL) two connection types, both connection types use TDD (time division duplex transmission scheme) to achieve full-duplex transmission;
7. The baseband controller uses three types of error correction schemes to achieve error-free data transmission;
8. The air interface is based on an antenna level of 0 dBm and complies with the FCC (United States Federal Communications Commission) standards relating to the 0 dBm ISM band;
9, in line with Bluetooth 1.0b version of the specification: software version is re. 1.08, hardware version is DIG8043390.
Carbon and its compounds A wide variety of carbons can also be alloyed with iron, the most common being carbon steel; graphite and clay can be used to make pencil cores for writing and painting, and graphite can also be used as a lubricant and pigment as a glass. Molding materials for electrodes and electroplating, electroforming, electric motor brushes, and neutron deceleration materials in nuclear reactors; coke can be used in barbecue, drawing materials and ironmaking industries; gem-quality diamonds can be used as jewelry, industrial Diamond is used for drilling, cutting and polishing, as well as tools for machining stones and metals.
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