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RF Based Wireless Remote Control System

It is often required to switch electrical appliances from a distance without being a direct line of sight between the transmitter and receiver. As you may well know, an RF based wireless remote control system (RF Transmitter & RF Receiver) can be used to control an output load from a remote place. RF transmitter, as the name suggests, uses radio frequency to send the signals at a particular frequency and a baud rate.

The RF receiver can receive these signals only if it is configured for the pre-defined signal/data pattern. An ideal solution for this application is provided by compact transmitter and receiver modules, which operate at a frequency of 434 MHz and are available ready-made. Here, the radio frequency (RF) transmission system employs Amplitude Shift Keying (ASK) with transmitter (and receiver) operating at 434 MHz. The use of the ready-made RF module simplifies the construction of a wireless remote control system and also makes it more reliable.

RF Transmitter

This simple RF transmitter, consisting of a 434MHz license-exempt Transmitter module and an encoder IC, was designed to remotely switch simple appliances on and off. The RF part consists of a standard 434MHz transmitter module, which works at a frequency of 433.92 MHz and has a range of about 400m according to the manufacture. The transmitter module has four pins. Apart from “Data” and the “Vcc” pin, there is a common ground (GND) for data and supply. Last is the RF output (ANT) pin.

Pin Assignment of the 434MHz Transmitter module

Note that, for the transmission of a unique signal, an encoder is crucial. For this, I have used the renowned encoder IC HT12E from Holtek. HT12E is capable of encoding information which consists of N address bits and 12N data bits. Each address/ data input can be set to one of the two logic states. The programmed addresses/data are transmitted...