The document describes an FM receiver project. It includes the group members, an overview of radio receivers and how they work, classifications of receivers, details on AM and FM receivers, the circuit diagram and components of the FM receiver, and descriptions of the main sections in the block diagram including the RF amplifier, mixer, filter, IF amplifier, limiter, demodulator, AF amplifier, and oscillator.

2. PROJECT NAME.
FM RECEIVER

3. Group Members.
 NASRULLAH KHAN (Group Leader) 13EL 07
 YOUSAF KHAN 13EL 59
 QADEEM KHAN 13EL 72

4. Radio Receiver.
 In radio communications a receiver is an electronic
circuit that receives radio waves and converts the
information carried by them to a useable form.
 It rejects the unwanted signal.
 It demodulate the carrier signal to get back the
original modulating signal.

5. classification of radio receivers
 Radio receivers are classified in to the fallowing
types
1. A.M. broadcast receivers
2. F.M. broadcast receivers

6. AM Receiver.
 AM Receivers is an electronic circuit which receive
Amplitude Modulated signals.
 AM Radio receiver range from 535 KHz to 1705 KHz
 AM Receiver and transmitter are simple but it need
synchronization
 AM Transmitters were first carried out successfully in
the mid of 1870s.

7. FM Receiver.
 FM receiver is the circuit that receive Frequency
Modulated signals.
 Its frequency rages from 88 to 108 Mega Hertz.
 FM Receiver and transmitters are more complex as
compare to AM Receiver.
 FM Receiver was developed in United State in 1930s.

8. CIRCUIT DIAGRAM OF FM RECEIVER

9. Components of FM Receiver.

10. Trimmer capacitor
 Trimmer capacitor is a variable capacitor which is used
to initially set the oscillator frequency value in a
circuit.

11. Transistor BF 494
 It is a medium frequency transistor which is used in
FM, AM receiver for low noise mixer.

12. IC LM 386
 IC LM 386 is an integrated circuit used in FM receivers
as a low voltage audio power amplifier.

13. Telescopic Aerial
 It is an Antenna used in FM, AM and wireless phones
to receive the signals.
 It convert the receiving signal in tiny Alternating
Currents which are applied to receiver and the receiver
extract the desired information.

14. Block Diagram.

15. Sections of Block Diagram of
FM Receiver

16. RF amplifier.
 A radio frequency power amplifier (RF power amplifier) is
a type of electronic amplifier that converts a low-
power radio-frequency signal into a higher power signal.
 Typically, RF power amplifiers drive the antenna of
a transmitter.

17. Mixer.
 In electronics frequency mixer is a nonlinear electrical
circuit that creates new frequencies from two signals
applied to it.
 If two signals at frequencies f1 and f2 are applied to a
mixer, and it produces new signals at the
sum f1 + f2 and difference f1 − f2 of the original
frequencies.
 Mixers are widely used to shift signals from one
frequency range to another, a process known
as heterodyning.

18. Filter.
 Ceramic filters are electronic components used as the
band pass element for Intermediate Frequency (IF)
amplifier stages of an FM radio.
 It reject the unwanted signal received by antenna.

19. IF Amplifier.
 Intermediate Frequency Amplifier is used to amplify
the Intermediate Frequency received from filter.
 IF amplifier is used to strengthen the intermediate
frequency (IF) before forwarded to the limiter block.

20. Limiter.
 The signal received from IF Amplifier is applied to
limiter which remove noise from received signal and
gives a constant amplitude signal.
 Limiter (delimiter): fatherly damping function which
is modulated amplitude waves (the signal sent by the
transmitter) in order to form a pure FM signal.

21. Demodulator.
 A demodulator is an electronic circuit that is used to
recover the information content from the modulated
carrier wave.
 Demodulation is extracting the original information-
bearing signal from a modulated carrier wave.
 FM demodulation or detection involves changing the
frequency variations in a signal into amplitude
variations at baseband, e.g. audio.

22. AF Amplifier.
 In radio equipment Automatic Frequency
Control (AFC), also called Automatic Fine
Tuning (AFT), is a method or circuit to automatically
keep a resonant circuit tuned to the frequency of an
incoming radio signal.
 It is primarily used in radio receivers to keep the
receiver tuned to the frequency of the desired station.

23. Oscillator.
 In electronics a local oscillator (LO) is an electronic
oscillator used with a mixer to change the frequency of
a signal.
 This frequency conversion process also
called heterodyning produces the sum and difference
frequencies from the frequency of the local oscillator
and frequency of the input signal.
 Processing a signal at a fixed frequency gives a radio
receiver improved performance.

24. Model.