For the Home Technology Enthusiast

Home Automation Basics



What is Home Automation?

Traditionally home automation has dealt with the electronic control of lighting, appliances and audio/video systems in the home. More recently, home automation has expanded to address and integrate home security functions as well. Unlike home networking, home automation has been less aggressive about standardization. Majority of home automation systems remain proprietary implementations. At best, the technologies have been licensed for use by others and only a few are completely open to the public.


Home automation in its current state is both a blessing and a curse. Because standardization had not been a big thrust, the consumer is left with numerous technologies and products to choose from. Some of these have become de facto standards owing to their popular usage in some corner of the world. One such de facto standard technology is X-10. A number of resources are available on the Internet that discuss this technology. Check out website for information on X-10. 


Here are some highlights of the technology:

  • Primarily intended to control lighting and appliances within a home

  • Simple to implement

  • Limited - very limited when compared to other networking technologies - in scope. Can do only a few things such as turning ON, turning OFF, increasing/decreasing brightness, etc.

  • Uses existing power cables within home or RF signals for communication between controllers and modules

A X-10 based home automation system generally consists of a controller and a set of modules and sensors. The controller is the 'brains' of the system that sends commands out to the modules and/or receives signals from the sensors. A variety of controllers are available too - from simple manually operated ON/OFF controllers to units that can be programmed via a computer to control a variety of X-10 modules in an autonomous manner. Figure below illustrates a X-10 based automation network.



Check out for more information on x-10 compatible modules, sensors, and a host of other products. 


Implementing a home automation project starts with determining what entities need to be controlled and in what manner. Control can be done manually, or by timers, or by sensors, or by any combination of the above. For instance, a front porch light can be controlled by a timer to turn ON at a certain time and turn OFF at a certain time. Whereas, a driveway light can be turned ON by a motion sensor on the driveway and turned OFF by a timer. And so on.

Controllers are available in the market that can be operated remotely through a touch-tone telephone also, allowing for remote control of your home automation network.


X-10 based home automation can be implemented in an incremental manner. Modules and sensors can be added to the network - up to a limit of 256 entities in total - as the need arises.


Important issues to watch for when implementing a X-10 based home automation system:

  • The technology is not reliable when operating across different phases of power. Meaning, a typical house in the US has two phases (or circuits) of power. X-10 signals do not bridge the phases and so a controller connected to one phase cannot control or communicate with a module connected to the other phase. Special 'signal bridges' are available to solve this problem. But before installing signal bridges, one could consider the use of two separate controllers - one for each phase.

  • Each X-10 module is identified uniquely in the network by a House code and a Unit Code combination. It is this unique identification that allows a controller to control a specific module. Since X-10 uses existing power cables, the signals that the controller transmits also goes to neighboring homes that are connected to the same street transformer. This could cause interference between controllers and modules that have the same house code and unit code. The only way to solve this problem is for homes connected to the same street transformer not to use the same house code.

  • X10 signals are susceptible to interference by a noisy appliance - an appliance that generates extraneous electrical signals on the power cables can prevent  reliable operation of your network. In such instances, it is necessary to connect the appliance to its power outlet through a noise filter.

Audio/Video Systems

Control of audio and video systems is typically done manually through a remote control that uses Infrared technology. Electronic devices are available in the market that extend the use of remote controls to a user's convenience such as being able to control the audio system physically located in one room from another room, etc. Such devices often use RF technology. 


RadioShack is a major dealer of such products. Check out for more information and products.


Major players in Home Automation technology (not dealers)

  • x10 (

  • Leviton (

  • Honeywell (


Given the variety of automation technologies and systems available in the market, a home user would be best served with a customized solution that above all meets the desired level of automation at the desired overall cost.