System for high speed digital transmission in repetitive noise environment
First Claim
1. A transceiver system for high speed digital, low bit-error rate digital communication on an a.c. power line in a repetitive noise environment comprising:
- a microprocessor having a memory and a system clock;
zero-crossing means coupled to an a.c. power line to detect the beginning and end of each cycle of alternating current;
counter means connected to said zero crossing means and to said system clock wherein said counter means is activated by said zero crossing means at the start of an a.c. cycle and deactivated by said zero crossing means at the end of an a.c. cycle and wherein said counter means counts cycles of said system clock during each a.c. cycle;
impulse detection means coupled to said a.c. power line to detect impulse noise having an amplitude greater than a present threshold;
means to latch the count in said counter means at the start of a detected impulse noise;
means to latch the count in said counter means at the end of said detected impulse noise;
means to interrupt said microprocessor and write said latched counts in its memory;
means in said microprocessor to compare recorded impulse times in one a.c. cycle with recorded times in a second a.c. cycle, to determine periodicity of impulse noises in a plurality of said a.c. cycles, thereby predicting the times at which said periodic impulse noises will occur in subsequent a.c. cycles;
a modem having transmit and receive sections connected to said microprocessor and couples to said a.c. power line;
control means in said microprocesor to block said modem from transmitting or receiving during the predicted times of said impulse noises in each subsequent a.c. cycle.
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Accused Products
Abstract
A transceiver system for high speed, low bit-error rate data communications over a.c. power lines in the presence of repetitive impulse noise includes an a.c. power line coupling network, a power line communications modem, and a microprocessor with a memory and a programmed avoidance algorithm. The a.c. line coupling network includes a zero crossing circuit to detect the start of each a.c. cycle; a transient-voltage limiting front end to detect impluse noises above a threshold and minimize ringing, and a timing circuit to determine the time and duration of each impulse in each sampled a.c. cycle. The microprocessor records the start and stop times of impulses, repetitively scans several a.c. cycles and determines whether or not the impulses are periodic. For periodic impulses, the microprocessor blocks communication on the modem during the impulses, enabling the transceiver to transmit and receive between impulses.
112 Citations
11 Claims
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1. A transceiver system for high speed digital, low bit-error rate digital communication on an a.c. power line in a repetitive noise environment comprising:
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a microprocessor having a memory and a system clock; zero-crossing means coupled to an a.c. power line to detect the beginning and end of each cycle of alternating current; counter means connected to said zero crossing means and to said system clock wherein said counter means is activated by said zero crossing means at the start of an a.c. cycle and deactivated by said zero crossing means at the end of an a.c. cycle and wherein said counter means counts cycles of said system clock during each a.c. cycle; impulse detection means coupled to said a.c. power line to detect impulse noise having an amplitude greater than a present threshold; means to latch the count in said counter means at the start of a detected impulse noise; means to latch the count in said counter means at the end of said detected impulse noise; means to interrupt said microprocessor and write said latched counts in its memory; means in said microprocessor to compare recorded impulse times in one a.c. cycle with recorded times in a second a.c. cycle, to determine periodicity of impulse noises in a plurality of said a.c. cycles, thereby predicting the times at which said periodic impulse noises will occur in subsequent a.c. cycles; a modem having transmit and receive sections connected to said microprocessor and couples to said a.c. power line; control means in said microprocesor to block said modem from transmitting or receiving during the predicted times of said impulse noises in each subsequent a.c. cycle. - View Dependent Claims (2, 3)
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4. A transceiver system for high speed digital data communication over an a.c. power line comprising:
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an a.c. line coupling network; an a.c. power line communications modem coupled to said a.c. power line; a microprocesor having inputs from said a.c. line coupling network and controlling said modem by its outputs; said line coupling network comprising; means to determine the start/end of each cycle of said a.c. power line by detecting zero-crossings; means to detect the occurrence of impulse noise(s) during a cycle interval; means to count the time after a zero crossing at which each impulse noise occurs in an interval; means to latch said count; said microprocessor comprising; means to read and store said latched count(s) for said interval; means to determine repetitive patterns of impulse noise times in a plurality of cycles; and means to block communication by said modem during times in each a.c. cycle when repetitive impulses occur. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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Specification