1, common wireless fsk There are analog optical terminal machine and digital optical terminal machine Wireless fsk, is the solutionTen or even hundreds of kilometers of TV monitoring transmission Wireless fsk Wireless fsk, by converting and controlling signals into laser signals in optical fiber transmission. Its advantages are wireless charging fsk : long transmission distance, small attenuation, good anti-interference performance, suitable for long-distance transmission.
2, there are many ways of radio communication, including: broadcast communication: This is the most common way of radio communication. Radio stations transmit audio through modulationThe signals are converted into radio frequency signals, and then transmitted into the air through the antenna, the radio receives these signals and then demodulated back into audio signals for people to listen to. Television communications: Similar to broadcast communications, television communications also transmit video and audio signals via radio waves.
3, radio broadcast communication Radio broadcast communication is an important way of radio communication, it uses radio waves to transmit sound, images and other information to the vast audience's radio or television. This method is widely used in the communication of news, music, weather forecast and other fields. Mobile communication Mobile communication is one of radio communicationA kind of important application, mainly including mobile phone communication, wireless LAN and so on.
4, [crosstalk] in a channel, due to the influence of other channel signal energy generated by the useless signal. Any electrical disturbance in a transmission path or device other than a useful signal. [Signal-to-noise ratio] The ratio of the average signal power to the average noise power is called the signal-to-noise ratio, referred to as the signal-to-noise ratio or signal-to-noise ratio.
5, continuous wave telegraph communication (continuous wave) Continuous wave telegraph communication (continuous wave) referred to as CW mode. It controls the hair by a keyThe machine generates short signals. (dot) and long signals. (dash), and uses different combinations of them to represent different characters to form words and sentences. CW requires the simplest equipment, occupies a very narrow frequency band and has high transmission efficiency, and the communication distance is longer under the same conditions.
ZigBee technology: ZigBee technology is a wireless LAN technology based on the IEEE 8014 standard. It is mainly used for communication between low-power devices, such as sensor networks, smart homes, etc. ZigBee technology has the characteristics of low power consumption, low cost, flexibility and scalability. Bluetooth technology: Bluetooth technology is a short-range wireless communication technology, mainly usedConnect mobile devices, headphones, stereos, etc.
China's common wireless wide area communication network mainly includes CDMA, GPRS, CDPD three types of network standards. CDMA network system, CDMA (CodeDivisionMultipleAccess), also known as code division multiple access, is used on wireless communication technology, CDMA allows all users at the same time using band, is China unicom CDMA network operation of the network, then introduce CDMA1X network system, a more stable.
Screen bright line, bright band or dark line this problem is generally the fault of the LCD screen. The bright line fault is generally a problem with the line connecting the LCD body or the driver IC of a row or column is damaged. The dark line is generally the body of the screen has leakage, or the TAB flexible plate connection is open. The above two problems are basically a death sentence for the machine, there is no maintenance value, because of a screenThe price is too high.
At present, there are four wireless technologies in the smart home field: WiFi, Zigbee, Zwave and Bluetooth, each of which has its advantages and disadvantages. Smart home WiFi, Zigbee, Zwave and Bluetooth technology introduction WiFi technology transmission speed, low product cost, and the most popular in life, based on WiFi technology smart home products accounted for the highest market share, its disadvantages are low security, weak stability, large power consumption, limited connected devices.
Hello, I am very pleased to explain to you the wireless transmission technology in the field of smart homeThere are the following: Power line carrier technology: mainly including X-10 and PLCBUS, in China's complex power grid environment, the grid clutter interference is serious environment, the operation state is difficult to ensure stability, especially in office buildings, commercial buildings and other places are very susceptible to high-power electrical interference; Not suitable for large-scale applications.
Compared with the bus smart home system, the advantages of wireless are plug and play, no wiring, etc. But the mainstream Wi-Fi, ZigBee, Bluetooth in the home environment have their own shortcomings. There are many introductions on the Internet about the technology, I will not analyze the technology in detail, from the applicationCome up here and talk. Wi-Fi is a communication protocol based on IEEE8011, which is widely used in smart products and smart home appliances.
The application of WiFi technology in smart home is mature, with the advantage of low cost, but the device power consumption is large, the number of access is limited, and the networking ability is weak. WiFi solutions are suitable for applications that require little power consumption and a small number of devices, such as smart rice cookers, air conditioners and lamps. 8011ac technology may improve some of the shortcomings of WiFi solutions, but adoption will take time.
Lora is also a very hot wireless communication technology recently,