Design Of Long-Distance Remote Control Implement Based On Urban Network

Remote control technology is an technology for remote control of the controlled object which has been applied in life, all aspects of national defense without distance limitations, which has become an important science and technologyThis paper is to achieve telephone remote control which is an another function of telephone with software and hardware. The phone can be used to control electrical appliances such as electric lights, air conditioning, TV,etc. anywhere.The core technology is the DTMF coding theory and the MT8870 coding principles. Telephone remote control is compared to other remote control technology which does not take resources, without distance limitations, without electromagnetic radiation and special wiring is not needed With the popularity of the telephone, the technology goes into people's daily life which makes life more personalized so that people can feel convenience, freedom and comfortable in life which is brought by technology. It is a strong application, convenience, and benefit for people. The design of the system is separately designed and divided from the the various functional modules of system of the hardware and software. The system consists of several components such as automatically hook and hanging system, the ring system, the decoding system, microcontroller, voice circuit.When the telephone lines's loop current suddenly increases about 30mA, the Program-controlled telephone switches will respond to the telephone's off-hook. While the telephone switching system checks the increasing of loop current to determine the telephone off-hooks or not.We use a microcontroller unit to control a 300Ωresistor which connects at both sides of telephone line to make simple automatic pick hook circuit to simulate the hook and hang up, but the effect is not very good.So we design a constant flow source off-hook to connect with the lines to simulate the process-hook. We use the circuit to simulate the off-hook and the transistor constant flow source to maintain the state of off-hook.Constant folw source can be designed to ensure the circuit has smaller 300ΩDC resistance and larger 600ΩAC impedance which makes the circuit has good characteristics of sending and receiving yards.Because the local telephone network remote control is connected to a telephone line for remote control and is based on the dual tone multi-frequency DTMF signals for communication, in which we use dual tone multi-frequency DTMF to input the password,to control the choice of channel and the information. So the dual tone multi-frequency DTMF is an important part.The stability of the system depends entirely on the quality of its design.Telephone Remote Controller is to complete the exchange between the user and the system with voice prompts. First, the circuit will be pre-stored several sections of system voice prompts and then the central processing unit circuit to judge the DTMF signals sent by the user and then addressing, play as the corresponding reminder ring.The users can do the next step by the reminder ring.Long-distance remote control of local network is a uses multi-channel remote controller which uses AT89C51 single chip and DTMF decoding IC MT8870 as its'core and controled through the telephone lines.Users can do the operation of electrical equipment for remote control by phone which has a set of voice prompts and other functions.The system consists of 51 MCU main control unit, ringing detection unit, automatically off-hook, DTMF decoder circuit, the voice prompts circuit, watchdog and EEPROM and other structural components. This paper will introduce the function of various units and the principles of design in details, including the principle of DTMF,encoding and decoding MT8870 and the standards of ringing signal.Long-distance remote control of urban network can control the states of being controlled object remotely and can automatically pick or hang up, self-control phone on and off. The central processing unit in this system can decode and collect the DTMF signal sent by the remote port to complete a series of remote control operation.