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9 - A Carrier-current System for domestIc Remote Control
tion. They are synchronized to the zero crossing point of the AC power line. They must be
transmitted as close to the zero crossing point as possible, but certainly within 200 microsec-
ondsofthezerocrossingpoint.
A Binary 1 is represented by a 1 millisecond burst of 120 kHz at the zero crossing point, and
a Binary 0 by the absence of 120 kHz. These 1 millisecond bursts should equally be trans-
mitted three times to coincide with the zero crossing point of all three phases in a three phase
distribution system.
The figure below shows the timing relationship of these bursts relative to zero crossing.
09-timing
A complete code transmission encompasses eleven cycles of the power line. The first two cy-
cles represent a Start Code, as follows:
09-xst
Transmission windows
T : 20ms (50Hz)
T/6
T/3
X-10 Technology : Start code
1110
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