RF Module

A tiny electronic device that facilitates transmission of a signal between two devices can be termed as RF Module. Here RF stands for radiofrequency. It uses radio frequency to transmit signals. RF module is preferred over other similar techniques because it does not require the two devices to be in the line of sight of each other. It is generally seen that RF CMOS technology is employed to manufacture RF modules. If a system desires to establish wireless communication with the other devices then the RF module can definitely serve the purpose.
Components of the RF module
• Antenna
• Transmitter
• Receiver
• Printed Circuit Board
• Serial Interface

Types of RF Modules

Transmitter Module: It is capable of transmitting and modulating a radio wave. Generally, a microcontroller associated with it provides the data to be transmitted.

Receiver Module: These modules are responsible for demodulating the received modulated signals. One of their types is super regenerative module. Whereas the receiver modules that provide good stability and high accuracy for a quite large range of voltage and temperature are called as superheterodyne modules.

Transceiver Module: If an RF Module consists of receiver as well as transmitter then it can be termed as transceiver module. It mostly uses half duplex mode of transmission.

The transmitter is provided with a 3v-6v voltage supply. And the output power required for the transmitter is near about 4v-12v. The frequency range for the transmitter is around 433.92MHz. Whereas the frequency range of the receiver is 433MHz. The current supply to the receiver is 3.5mA. And the power required by the receiver to operate is 5v. Serial data transmission occurs between the transmitter and the receiver. In order to achieve efficient data transfer, the transmitter and receiver should be interfaced with the microcontrollers.

The radio wave can be modulated by varying either of its three components;
Namely amplitude, frequency and phase. Based on these components the techniques of modulation are
ASK(Amplitude Shift Keying)-All the available parameters of the information signal being sent are kept constant except the amplitude. Here the amplitude of the signal being transmitted is varied.
FSK(Frequency Shift Keying)-It involves the coherent or noncoherent shifting of frequencies. The digits 0 and 1 are represented using two distinct frequencies.
PSK(Phase Shift Keying) – All the available parameters of the information signal being sent are kept constant except the phase. Here the phase of the signal being transmitted is varied. The reference phase used for digit 0 is 0 degree whereas that for digit 1 is 180 degrees.

Protocol Standards governing RF Communication

Zigbee-It follows IEEE.802.15.4 standard and was developed by ZigBee Alliance. Its range varies between 10m-20m. It is a personal area network that consumes less power and less data rate. It uses a mesh network for transmitting data at farther distances.

Bluetooth Low Energy-It was developed by Bluetooth Special Interest Group. It also requires less power consumption and is also inexpensive. It uses 40 channels of 2MHz.And Gaussian Frequency Shift Modulation technique is employed for data transmission. It uses frequency hopping to deal with narrowband interference problems.

Wi-Fi-It is a cable elimination technology that follows the IEEE 802.11 family of standards. It is well suited for the objects that are in the line of sight. It mainly operates at 2.4GHz frequency and sometimes at 5GHz frequency.

Applications of RF Module

 Wireless Home Automation Systems
 Telemetry
 Digital video transmission
 Digital Audio Transmission
 Wireless Alarms
 Robotics
 Monitoring of vehicles
 Smart sensor applications
 Industrial remote controls