| 摘要 |
Invention herewith described refers to a PLC modem for communication over power line based on digital signal processing, according to the invetnion, represents a completely new conceptual solution of the construction being represented in the drawings, and which carries out transmitting the user data according to the procedure wherein the PLC modem receives user data over a digital interface (1), a microcomputer (2) processes the data through several layers of communication protocol (application layer, MAC layer and other used layers) all up to the physical layer whereon the signal is formed, further on, the microcomputer (2) generates digital sequence DS with a constant amplitude and zero autocorrelation or a digital sequence with similar properties, and enters user data into digital sequence DS (coding), and then microcomputer (2) sends DS sequence to a D/A converter (3), and this one produces an analogous signal which leads to a modulator (4) which translates spectrum of DS sequence into a frequency band wherein signals are transmitted on an electromagnetic net.PLC modem according to the invention, receives user data according to the processing wherein signal from electroenergetic network misfires the signal through a coupling circuit (8) which filters voltage of 50Hz/60Hz, and protects, protecting circuit (7) which limits the redundant currents and voltages coming from the net due to the interferences, and then transmits the outgoing signal from the output point of the protecting circuit (7) to the entry of the circuits for automatic regulation of amplifying AGC circuit (12) which provides constant level of a signal under different conditions of transmission through electromagnetic network where, thereupon, the signal from the output of the AGC circuit 12 passes through a filter (11) and is taken to the input of a demodulator (10) which translates the received signal into the main band, if there is a need, and then the signal is further taken to the input A/D of a converter (9) which digitalizes the analogous signal and transmits the data to the microcomputer (2) which decodes the data received so that it generates one or more relevant DS sequences and carries out decoding by using correlating techniques, where, thereupon, the microcomputer (2) further sends decoded data to higher levels of protocol which separate user data and send them to the digital interface (1).
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