Tham khảo tài liệu 'smart home systems part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Selected Home Automation and Home Security Realizations An Improved Architecture 51 Telephonic Method of Control Landline telephony has been serving as the major communication media used for teleconversation. Although the launching of cellular telephony and the internet based voice communication has reduced its usage landline telephonic network still enjoys its service due to its simplicity and cost effectiveness offered to subscribers. Using landline telephone controls were issued Balasubramanian 2003 by dialing additional digits for switching ON or OFF of the electrical appliances in home. An extension card attached to the home telephone identifies the digit decodes it and controls switching the appliances. Its principle is outlined in . In order to control switching the appliances in home the user dials the digits of home telephone. This gives ring in home telephone. The extension card attached to it counts the ring cycles and actuates a relay to close the cradle contacts despite the handset unmoved from cradle. The closing of contacts extends a gyrator and control bridge across the lines simulating the condition of establishing connection to home set. The additional digit dialed is decoded and the corresponding appliance is switched ON OFF by the relay circuit. Comparison of Remote Control Techniques In order to compare the features of remote control techniques considered here a simple hardware scheme employing these control methods in home automation unit is shown in . It does not however show the intruder detector and fire detector alarm units. Assuming all selected control schemes are available in the flat their features and performances are compared. The final control element of appliances of all control units are delivered from the relay board as commanded by word in relay register. At any instant of issuing the command from remote location the concerned control unit will write the control word into the relay register through the logic .
