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RF TRANSMITTER AND RECEIVER

BY

HEMANT RAJ KUMAR

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HISTORY OF RF MODULE

The first primitive radio transmitters (calledHertzian oscillators) were built by German

physist Heinrich Hertz in 1887 during his

pioneering investigations of radio waves. These generated radio waves by a high voltage

spark between two conductors.

These spark-gap transmitters were used duringthe first three decades of radio (1887-1917),

called the wireless telegraphy era.

http://en.wikipedia.org/wiki/Heinrich_Hertzhttp://en.wikipedia.org/wiki/Electric_sparkhttp://en.wikipedia.org/wiki/Spark-gap_transmitterhttp://en.wikipedia.org/wiki/Wireless_telegraphyhttp://en.wikipedia.org/wiki/Wireless_telegraphyhttp://en.wikipedia.org/wiki/Spark-gap_transmitterhttp://en.wikipedia.org/wiki/Spark-gap_transmitterhttp://en.wikipedia.org/wiki/Spark-gap_transmitterhttp://en.wikipedia.org/wiki/Electric_sparkhttp://en.wikipedia.org/wiki/Heinrich_Hertz

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Contu.

Earlier technologies were replaced by vacuum

tube transmitters in the 1920s, because they

were inexpensive and produced continuous

waves, which could be modulated to transmit

audio (sound) using amplitude modulation

(AM) and frequency modulation (FM).

http://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Continuous_wavehttp://en.wikipedia.org/wiki/Continuous_wavehttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Frequency_modulationhttp://en.wikipedia.org/wiki/Frequency_modulationhttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Continuous_wavehttp://en.wikipedia.org/wiki/Continuous_wavehttp://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Vacuum_tube

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RF MODULE

The RF module, as the name suggests,

operates at Radio Frequency.

The corresponding frequency range varies

between 30 kHz & 300 GHz.

In this RF system, the digital data is

represented as variations in the amplitude of

carrier wave. This kind of modulation is known

as Amplitude Shift Keying (ASK).

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RF TRANSMITTER RECEIVER MODULE

This RF module comprises of an RF Transmitter and anRF Receiver.

The transmitter/receiver (Tx/Rx) pair operates at afrequency of434 MHz. An RF transmitter receivesserial data and transmits it wirelessly through RFthrough its antenna connected at pin4.

The transmission occurs at the rate of 1Kbps - 10Kbps.

The transmitted data is received by an RF receiveroperating at the same frequency as that of thetransmitter

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CONTU.

The RF module is often used alongwith a pair

of encoder/decoder.

The encoder is used for encoding parallel data

for transmission feed while reception is

decoded by a decoder.

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PIN CONFIGURATION

http://creativentechno.files.wordpress.com/2012/01/rf-module-connections_0.png

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PIN FUNCTION OF TX/RX

Pin No Function Name

1 Ground (0V) Ground

2 Serial data input pin Data

3

Supply voltage; 5V

Vcc

4 Antenna output pin ANT

Pin No Function Name

1 Ground (0V) Ground

2 Serial data output pin Data

3 Linear output pin; not connected NC

4 Supply voltage; 5V Vcc

5 Supply voltage; 5V Vcc

6 Ground (0V) Ground

7 Ground (0V) Ground

8 Antenna input pin ANT

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RF MODULE KIT

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WORKING

An RF transmitter generates radio frequency waves in itscircuits, and to this 'carrier signal', it adds the information partbymodulating the carrier signal.

This composite signal (carrier plus information) is then fed to an

antenna (aerial).The aerial induces a corresponding signal into theatmosphere, by altering the Electric and Magnetic fields at(obviously) the same frequency.

The impedance of 'free space' is few tens of Ohms to a few

hundreds of Ohms.

The power emitted by the transmitter can vary from a megawatt orso (for VLF signals) to a few watts for handheld devices.

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CONTU..

An Rf receiver receives the signal from the atmosphere, from its ownaerial.

The receiver aerial is often quite simple, and the signal level is typically ofa few microvolts.This it tunes in (gets rid of unwanted signals andamplifies only the wanted ones).

The receiver circuits then strip the information part of the signal from thecarrier part, and amplify this to a useful level for audio or video.

The actual signal into the loudspeaker will be a few tens of volts. In spite of

the inefficiency of loudspeakers, (often only a few %) the signal eventuallyappears at a level that may be heard. A background radio will be a fewmilliwatts of power.

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FUTURE OF RF MODULES

Alpha Transmitter / Receiver Modules Paired FM Transmitter and FM Receiver

Modules

Data Rate up to 115Kbps Range up to 300 metres

FM Frequencies available: 433, 868 and

915MHz

Wide operating voltage 2.2V- 5.4V

http://www.rfsolutions.co.uk/acatalog/Alpha_Transmitter___Receiver_Modules.htmlhttp://www.rfsolutions.co.uk/acatalog/Alpha_Transmitter___Receiver_Modules.htmlhttp://www.rfsolutions.co.uk/acatalog/Alpha_Transmitter___Receiver_Modules.html

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THANK YOU