The Development Of Spread Spectrum Digital Transmission System On 10KV Power Line

The higher the power system automatic level, the more telemetering and remote controlling information need to be transmit accurately. Traditional \ rer line carrier communication has some shortcomings on communication quality, which let it doesn't adapt to the demand of the power developing. The channel-lacking problem is more apparent in the power system communication. Although many new communications means, such as microwave, optical fiber, etc, perform satisfactorily, the investment is tremendous and the construction period is long. If we can apply the spread spectrum technique on power line, improve the quality of the power line carrier communication, make the better use of the existing power line resource, then we can resolve the channel-lacking problem and bring direct and considerable social economic benefit. This scientific research project bases on this starting point, develops the spread spectrum digital transmission system which can accomplish the digital transmission on 1OKV power line.The design select the chirp as the spread spectrum technology, which resolve the problem of the signal transmission in such adverse communication circumstances as 10KV power line; select Advanced Multi-Band Excitation (AMBE) compressive coding as the voice compressive coding technology, which can realize the digital compression of the voice signal with high quality and low rate, utilize the bandwidtheffectively; select the general multiplication D/A converter to achieve automatic gain control function, thus overcome the attenuation characteristic of the power line high frequency passageway which effects the received signal.The paper firstly analyses the fundamental principles of the chirp technique, the Multi-Band Excitation (MBE) compress coding technique and the automatic gain control technique. Secondly, the hardware design and the software development are thoroughly discussed. The hardware design includes SSC P485 power line node, voice circuit and automatic gain control circuit. The software development comprises the compile of the microcontroller's assembly program and the compile of the communication program between the computer and the microcontroller. At last, the 10KV spread spectrum digital transmission system has made. The debugging and the performance analysis are conducted. The results of the laboratory and on-the-spot experiments show this digital transmission system performs superiority, pays cheaply. It can be used on the occasion of data transmission rate moderate, communication reliability demand high, such as power network automation, distribution network automation and remote automatic metering system and so on.