The product got another boost in 1997 when the patent expired and the design became an open standard and many manufactures jumped on the bandwagon with many new products. Technically the X-10 technology is quite straightforward and easy to follow. When the X-10 sends a message it consist of 13 bits. The last or function bit indicates whether the previous 4 bits should be interpreted as a unit code or a function code. The start code uses 3 consecutive 120 kHz burst followed by no burst to differentiate itself from regular data bits.
Every command is sent twice even thought the receiver only needs one.
The second being sent as insurance against noise or other line problems. An extended code was developed to provide additional capability out of the existing technology. With these additions lighting dimming, brightness control, temperature monitoring, switch acknowledgement and security functions are now available. As a side note X-10 also works on 50 Hz systems due to the systems works on the zero crossing points of the sinuate and not on the frequency. I hope this article sheds a little light on the X-10 standard for home automation, and we will cover different components of the systems for your home in the future.