| 摘要 |
In a power line data communications system, high-bit-rate digital data is transmitted through a communications media, having high harmonic noise content, by use of a frequency-modulated chirp waveform. The chirp waveform instantaneous frequency is at a predetermined center frequency at the start, midpoint and end of each bit time interval, and makes substantially linear frequency changes to a maximum frequency and a minimum frequency at selected ones of the one-quarter and three-quarter bit-time-interval times. A binary-one data bit is transmitted by increasing the instantaneous frequency to reach the maximum frequency at the one-quarter interval time, then decreasing the frequency to reach a minimum frequency at the three-quarter interval time, and reducing the instantaneous frequency thereafter to reach the center frequency at the end of the bit time interval. A binary-zero data bit is transmitted by initially decreasing the instantaneous frequency to reach the minimum frequency at the one-quarter interval time, then increasing the instantaneous frequency to reach the maximum frequency at the three-quarter interval time, and reducing the instantaneous frequency thereafter to reach the center frequency at the end of the bit time interval. One presently preferred embodiment of apparatus for transmitting the chirp frequency-modulation signal, and one presently preferred embodiment of apparatus for receiving the chirp frequency-modulated waveform for recovering the data modulated thereon, and associate timing information, are disclosed.
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