Wireless communication mainly includes microwave communication and satellite communication. Microwave is a kind of radio wave, and the distance it transmits is generally only several tens of kilometers. However, the frequency band of the microwave is wide and the communication capacity is large. Microwave communication should build a microwave relay station every few tens of kilometers. Satellite communication is the use of communication satellites as relay stations to establish microwave communication links between two or more earth stations on the ground or between mobile bodies.
Language is the most important communication tool for human beings and the main expression for people to communicate. In the age of the Internet of Things, when machines need to communicate, they also need to be in a language that they can understand each other. Today, we will take a look at the wireless short-range communication languages ​​and technologies that are commonly used in the Internet of Things--Huawei Hilink protocol, WiFi (IEEE 802.11 protocol), Mesh, Bluetooth, ZigBee, Thread, Z-Wave, NFC, UWB, LiFi.
TOP1 LiFi, a photo-fidelity technology, is a new wireless transmission technology that uses visible light spectrum (such as light from a light bulb) for data transmission. It was invented by Professor HaraldHass of the University of Edinburgh in the United Kingdom.
The visible light communication technology uses a high-speed light and dark flashing signal that is invisible to the naked eye, such as a fluorescent lamp or a light-emitting diode, to transmit information. The high-speed Internet wire device is connected to the lighting device, and the power plug can be inserted.
LiFi is equivalent to Wi-Fi's visible light wireless communication (VLC) technology, which can transmit light and light through the light of a light-emitting diode (LED) light bulb. It can provide both lighting and wireless networking without electromagnetic interference, which can help alleviate the current network traffic. Increased problem.
TOP2 Hilink protocol: Huawei's self-developed smart home "three-piece" - Hilink protocol, Huawei-LiteOS system and IOT chip.
The HiLink protocol is a "mandarin" between smart devices. It can be quickly accessed, easy to use, safe and reliable, compatible with multiple protocols, and open to SDK. It is another historic breakthrough after Huawei HiSilicon chip. The Hilink connection agreement and Huawei's previously launched Liteos IoT operating system will become two core capabilities shared by Huawei and its partners.
TOP3 WiFi: Usually WiFi technology uses 2.4GHz and 5GHz surrounding frequency bands, and a wired router can connect a wired router to a WiFi signal. In 2016, the WiFi Alliance recently announced the 802.11ah WiFi standard—WiFi HaLow, which enables WiFi. Applied to more places.
Wi-Fi is a brand of wireless network communication technology designed to improve interoperability between wireless network products based on the IEEE 802.11 standard. At present, people generally confuse Wi-Fi with IEEE 802.11. Even equating Wi-Fi with the wireless internet. There are many types of Wi-Fi styles, there are wireless cards, and computers are connected. In September 2015, the wifi signal data collected by Skyhook and Mapbox showed that the global wifi signal was as much as 900 million.
The TOP4 wireless Mesh network, known as the cheap "Last Mile" broadband access solution, utilizes a multi-hop wireless mesh structure to provide broadband access to mobile users.
Mesh is a combination of WLAN and mobile Ad Hoc (peer-to-peer) networks. Compared with the WLAN, each network terminal can communicate directly with each other, and no longer needs to be forwarded by the AP (base station), and the coverage is larger. Compared with Ad Hoc, due to the fixed and power-filled backbone router, there is no need to consider too much in terms of mobility and power consumption.
TOP5 ZigBee/802.15.4 protocol. Zigbee was officially proposed in 2003. It appeared to compensate for the high complexity of the Bluetooth communication protocol, large power consumption, close distance, and small network size. The name is taken from the bee. The bee is a "dance" that flies the wings by flying and "zig" to communicate the position information of the pollen with the companion. By this way, the communication network in the group is formed.
ZigBee uses self-organizing network to communicate, and is also the most famous wireless communication protocol in the field of wireless sensor networks. In a wireless sensor network, when a message of a sensor cannot be smoothly transmitted from a certain communication path, the dynamic router can quickly find another channel transmission data at a close distance, thereby ensuring reliable transmission of information.
TOP6 Thread / IEEE 802.15.4 protocol. Thread and ZigBee belong to the same 802.15.4, but have made great improvements for 802.15.4.
Thread is a protocol based on IPv6, which is a great optimization in both transmission security and system reliability. It can carry Qualcomm Haier dozens of enterprise group Internet of Things Alliance AllSeen, but also Apple's Homekit smart home platform. Google's Nest has set Thread as the only communication protocol for the home Internet of Things. Then Nest launched the industry alliance, and the alliance members jointly promoted the Thread protocol. Thread short-range communication is also promising.
TOP7 Z-Wave protocol. The Z-Wave wireless networking specification was introduced in 2004 and is led by Danish chip and software developer Zensys, which promotes its application.
Z-Wave operates at 908.22 MHz in the US and 868.42 MHz in Europe. It uses wireless mesh network technology, so any node can communicate directly or indirectly with other neighboring nodes within the communication range. The data rate includes 9.6 kbps and 40 kbps, and the effective coverage of the signal is 30 m indoors and over 100 m outdoors. Z-Wave is an emerging RF-based, low-cost, low-power, high-reliability, short-range, narrow-bandwidth application. Z-Wave focuses on home automation, is popular in Europe and the United States, enters the Chinese market later than Zigbee, and its market share is far less than Zigbee. Due to the frequency band division, although it can develop in China, it is also cautious.
TOP8 Bluetooth / IEEE 802.15.1 protocol.
Bluetooth technology first began in 1994 and was developed by Swedish Ericsson. It uses Frequency-hopping Spread Spectrum and the communication band is 2.402G Hz-2.480GHz. Up to now, nine versions have been updated, namely Bluetooth 1.0/1.1/1.2/2.0/2.1/3.0/4.0/4.1/4.2, and the communication radius extends from a few meters to several hundred meters.
TOP9 NFC, Near Field Communication, developed jointly by Philips Semiconductors, Nokia and Sony in 2002. In 2004, the NFC Forum was established to standardize and promote near-field communication technology, which was evolved from the integration of RFID and interconnection technologies.
NFC is a short-range high-frequency radio technology with an operating frequency of 13.56 MHz and a distance of 20 cm. The transmission speed is 106 Kb/s, 212 Kb/s or 424 Kb/s. Data reading and exchange are performed through three business modes: card, card reader and peer-to-peer. NFC and Bluetooth technology functions similarly, but the transmission rate and transmission distance are not as fast and far as Bluetooth, while the power consumption and cost are low, and the confidentiality is good. These advantages make it the darling of mobile payment and consumer electronics. Recently, Apple pay and Samsung pay have made a big splash in the field of mobile payment. The importance of NFC technology in the future mobile Internet world is self-evident.
TOP10 UWB, ultra-wideband, a carrierless communication technology that uses n-second to picosecond non-sinusoidal narrow-pulse transmission data to achieve hundreds of Mb/s to several Gb/s data transmission in the range of 10m or so. rate.
UWB has many advantages such as strong anti-interference performance, high transmission rate, wide bandwidth, low power consumption, small transmission power, etc. It is mainly used in indoor communication, high-speed wireless LAN, home network, cordless telephone, security detection, position measurement, radar, etc. field. More interestingly, the standardization of UWB has been controversial, which indirectly slowed down its promotion. Compared with wireless communication such as Bluetooth, 802.11b, 802.15, UWB can provide faster, farther, and wider transmission rates, and more and more researchers are investing in the UWB field.
Francis turbines are the most common Water Turbine in use today. They operate in a water head from 40 to 600 m (130 to 2,000 ft) and are used primarily for electrical power production. The electric generators that most often use this type of turbine have a power output that generally ranges from just a few kilowatts up to 800 MW, though mini-hydro installations may be lower. Penstock (input pipes) diameters are between 3 and 33 ft (0.91 and 10 m). The speed range of the turbine is from 75 to 1000 rpm. A wicket gate around the outside of the turbine's rotating runner controls the rate of water flow through the turbine for different power production rates. Francis turbines are almost always mounted with the shaft vertical so as to isolate water from the generator. This also facilitates installation and maintenance.
Francis Turbine,Stainless Steel Francis Turbine,Francis Turbine Radial Flow,Stainless Steel Francis Turbine Runner
Shenyang Zhicheng Heavy Machinery Manufacturing Co., Ltd. , https://www.zhichengmachinery.com