Power line communication basic way

( Industry news] Power line communication basic way atltech P powerline communication way of local power companies wiring structure of distribution network has a broad, can transmit power, also can be used as a communication media, including the Internet. S in the century ago, ac power cord in addition to the transmission, used only for simple low speed data communication, such as the meter reading, load control, etc. Low-speed data communication application of application is limited to the inside of the low-voltage distribution transformer, distribution transformer should be placed 5 concentrator, transmitted by PSTN, optical fiber, or radio equipment. In Europe, the first distribution transformer a baixin settlement services, and lived in the United States is only a point, and automatic meter reading technology used in Europe at the earliest. With the deregulation of the telecommunications act, the power sector to business communication service, American families share a pole on the transformer can provide the following business: local telephone access, Internet access, electric meter, water meter, gas meter readings, power load management, theft alarm, fire alarm monitoring, etc. Faced with ac power line as communication medium problem is noise the damage to the data communication and signal attenuation, in recent years, these problems have been resolved. With reference to the open systems interconnection reference model, USES the hierarchical design scheme of three layers, with optimization design makes power to overcome the adverse environment. Using highly integrated chipsets can easily realize the simplified three layer architecture, its underlying includes the physical, low-level link protocol, and media access control ( MAC) Sub-layer, can compensate power lines of any critical condition. The second layer to the data link control, at the highest level for the application layer. Communication protocols, powerline physics American FCC allow MHz as powerline communication frequency band. The past of the electric power communication MODEM to KHz carrier frequency, modulation frequency shift chain control ( FSK） Or amplitude shift keying ( 问) 。 When electric insert or pull out the power supply socket, this kind of power line communication MODEM often need to be adjusted, to adjust the attenuation of signal and noise. Generally speaking, spread spectrum system has a good noise attenuation and frequency of the power line noise resistance effects such as the letter and synchronization issues. In the physical layer using a unique spread spectrum technology provides quick synchronization, make power line communication fast, reliable, practical, make the data to continuous sequence of bits transmitted in short frame. Physical level also in fast equalization effect, make the receiving signal of noise attenuation and frequency compensation. China cable net all rights reserved, reprint please indicate the low-level from China cable network, reliable link protocol data link layer has three key features, make the large network, multiple node can run reliably in the power line. First, the link protocol is longer than the packet from the user into shorter frame of power lines. Short for power transmission, the frame is necessary, because the transmission more long the greater the damage. Second, the link protocol provides reliable error correction and error detection, when I received the frame of the data for testing, and determined the retransmission of frames. Third, the link protocol provides adaptive equalization, due to the noise and attenuation in thousands on the power line of the order of magnitude of milli time change, if not timely compensation, signal will be lost. , media access control ( MCA) Sublayer sublayer USES the media access control MAC algorithm, MAC algorithm used in the private line cannot be transferred to the power line. Token passing is suitable for power line. On the power line, it is difficult to distinguish between noise and signal, token passing in the noise environment ensure the reliable transmission of the thirty thousand handshake between nodes without loss of the token. Because the position of each node each are not identical, each node in different noise transmission and attenuation 'hear'. There is this possible, some sites lost a transmission, transmission and other sites is 'hear'. In token passing, node before did not get the token cannot be transmitted, so any other each node node transmission could not be sent. The Caledonian gloria Tony cable co. , LTD. , Shanghai office contact person: ms zou email penny @ caledoniancables. Com company website HTTP / / WWW. caledoniancable。 com（ Chinese) http / / www。 caledoniancables。 es（ Spanish) Sohu blog: HTTP / / caledonianpenny. 博客。 搜狐。 Com [atltech edited]