Saturday 3 September 2016

RF Receiver and Transmitter [Simple Steps]

Introduction to RF Receiver and Transmitter 

What is RF?

Radio frequency (RF) is any of the electromagnetic wave frequencies that lie in the range extending from around 3 kHz to 300 GHz, which include those frequencies used for communications or radar signals. RF usually refers to electrical rather than mechanical oscillations. However, mechanical RF systems do exist (see mechanical filter and RF MEMS). more info: Wikipedia 

RF Transmitter:

Rf transmitter is a combination of electronics components (like Resistors ,capacitors, transistor, Oscillator etc.)  assembled on a PCB board.
The basic principle of RF transmitter is to transfer a data to Receiver by "Encoder" after modulation using oscillator and other amplification ICs. The transmission rate of RF is in the range of 1Kbps-10kbps which is sufficient to transfer 8-bit data one at a time.

RF Receiver:

RF receiver module receives the modulated RF signal, and convert the information in usable form. It receives signals through antenna it receives all the wave in the receiving range(ie. kHz to 300 GHz).
The antenna intercepts radio waves and converts them to tiny alternating current which are applied to the receiver, and the receiver extracts the desired information. After receiving the signal the electronic filters to separate desirable radio waves. Now it is turn of "Decoder" to decode the signals.

Flow diagram for communication between RF Receiver and Transmitter:


Encoder IC:

An encoder is a device, circuit, converts information from one format or code to another, for the purposes of standardization, speed or compression.
Encoder IC send a data with a particular address or in encrypted from which is only decoded by IC which is set on same the address.
HT12E Encoder IC is commonly used for Radio Applications. It can transfer 12-bits of parallel data in which 8 Address bits and 4 data bits.

Decoder IC:

decoder is a used to decode the signal with is coming from encoder though any type of medium. It decode serial data to digital output like "1001" by using some logic gates(like AND ,OR,XOR etc.).It contains very complex combination of these gates which is difficult to understand.Bye the way, this is not our concern :)

Now we know basics about Rf and Decoders and Encodes Let's start some practical....

Direct communication between Decoder and Encoder: 

Here  we will see how to communication between Encoder an Decoder via connecting wire between Input and output pin of Encoder an Decoder so are you ready to start making simple circuit as given blow.

Circuit Diagram 

There is no need to connect connect A0-A7 because there pins are use to set address that we use in RF transmission.

Now when you start pressing switch the corresponding LED will blink and LED which is connected to pin 17 is shows whether signal coming or not. When it blinks it means one of the switch is pressed

Note: The ratio of resistors in Encoder to Decoder is in the range of 5 to 7 and values of there resistors should be the order of 100k ohm(ex. 660k ohm for Encoder and 100k ohm for Decoder).

Let's go to the next step....

Communication using RF receiver and transmitter:

Here  we will see how to communication  between Encoder an Decoder RF receiver and transmitter through radio waves between Input and output pin of Encoder an Decoder so are you ready to start making simple circuit as given blow.

Circuit Diagram 

Here you can set you address as you want so that no other signal will interfere with your signal.

Why it is necessary to set address ? 
Let't take an example..
You are in a contest of robotics where many participants come with there bots than it might be possible that your robot will distract with other's radio signals but one you set your unique address than it will not take any unwanted signal surrounded it.

Note: The address pins of decoder and encoder will be switch on in same manner like Encoder set to "10000101" than Decoder should also be "10000101". (here "1" denote ON and "0" for OFF for each pin).

Now you are able to do experiments with this because you have a 4-bit data signal. You can use it in you Remote Control Bot and Home automation and other many things. now it is depend on you that how you use it.

If you make something new using RF than write in comment box.
We meet in next article which is RF control BOT(Car).

I hope you have enjoyed this :)
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For any suggestion and query please write in comment box.


  1. Very good tutorial. Carry on the good work. Great going. :)