The Internet Power Line Adapter - University of Queensland
The Internet Power Line Adapter - University of Queensland
The Internet Power Line Adapter - University of Queensland
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Home Automation, <strong>Power</strong> <strong>Line</strong>s and the <strong>Internet</strong> Quenten Alick<br />
transmit. In this manner, is should be possible to chain transceivers together to<br />
have a single controller controlling more than 16 devices.<br />
2.2.2 X-10 Transmission Protocol<br />
<strong>The</strong> X-10 transmission protocol is concerned only with sending pure digital<br />
data. <strong>The</strong>refore the only two signals which can be sent are a logical one and a<br />
logical zero. This information is transmitted at the zero crossing point <strong>of</strong> the<br />
50Hz power signal. Logic one is represented by the presence <strong>of</strong> a 120kHz PCM<br />
(Pulse Code Modulation) burst 1ms in length at the zero crossing point. Logic<br />
zero is represented by the absence <strong>of</strong> this burst. Bursts are transmitted three<br />
times per AC cycle to allow the receiver to gather the data even if it is located on<br />
a different phase to the transmitter. <strong>The</strong> transmission points are highlighted in<br />
figure 2-1. Of course for this to work coupling between phases is required but<br />
devices that can perform this are commercially available.<br />
Transmission points<br />
Figure 2-1 X-10 transmission signal<br />
1ms 120kHz burst<br />
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