Importance

Loading Importance Indicators...

Abstract

A system for communicating digital information over wires having a great deal of harmonic distortion, attenuation and noise, such as a power line, employs a transmitter which generates a signal representing a symbol of data. Some form of signal modulation such as Differential Phase Shift Keying (DPSK) or Frequency Shift Keying (FSK) is used to encode the data. The transmitter will continuously transmit or retransmit each data symbol until an acknowledgment is received from a receiving device. At the receiving device, the received signal is sampled and multiple repetitions of the same symbol are averaged to reduce noise. The averaged samples are then analyzed to demodulate the data. Both transmitting and receiving devices are clocked at the same frequency which is derived in both from the fundamental power line frequency. As such, the generation and detection of the data signals is coherent, making it possible to average out the effect of noise over multiple frames thereby ensuring communication even over highly noisy transmission media.

Loading the Abstract Image...

First Claim