Research Of Ultra-narrow Bandwidth Technology’s Application In Power Line Communication

Power line communication makes use of distribution network low line to transmit high speed data, voice, image and other multimedia signal, without wiring, wide coverage, convenient connection, however, the high speed data communication’s requirements make the single channel bandwidth consumption increases rapidly, the existing modulation method can not fundamentally solve the problem. In order to improve the utilization rate of frequency band, the paper applys the ultra-narrow bandwidth technology to the power line communication.This paper explains the controversial issues in the ultra-narrow bandwidth technology in detail, focusing on sine-like VMSK technology of ultra-narrow bandwidth. It also explains the influence of the power spectrum based on its unique characteristics on the control parameters for modulation of VMSK modulation signal when the sine zero, amplitude, signal correlation. On signal demodulation, the sine-like VMSK modulation signal with different control parameters detecting the amplitude and zero crossing detection for simulation, analysis, and then draws the related conclusion. On the basis of relevant demodulation, this paper proposes a new kind of sine VMSK signal demodulation method and gives the conclusion that the correlation coefficient calculation has a good demodulation performance.Transmission circuit on the signal of ultra-narrow bandwidth modulation must have very narrow bandwidth of noise characteristics, and keep the mutations phase information at the narrow band in intact. The key of the ultra-narrow bandwidth is to realize zero group delay. In this paper, the zero group delay filter is simulated and analyzed, and leads to multiple window function. With the control parameter increasing, the power spectrum of signal of Sine-like VMSK modulation is increasingly concentrated. When it is close to the"1" has a very narrow bandwidth, at the same time, the line spectrum and continuous spectrum is also more and more compact, the main part is focused to a small area. Based on the analysis of window function characteristics, its multiple bandpass characteristics and zero group delay characteristics is corresponding to the characteristics of sine-like VMSK modulation. This paper presents a parallel ultra-narrow bandwidth transmission scheme to make full use of ultra-narrow bandwidth characteristics.The ultra-narrow bandwidth technology applied to power system communication presented in this paper provides an effective means to improve the utilization rate of the power line communication.