Design And Construction Of An FM Receiver Using TDA7000

ABSTRACT

Radio receiver design includes the electronic design of different components of a radio receiver which processes the radio frequency signal from an antenna in order to produce usable information such as audio. This project only concentrates on fm receiver design. The complexity of a modern receiver and the possible range of circuitry and methods employed are more generally covered in electronics and communications engineering. The term fm receiver is understood in this project to mean any device which is intended to receive a radio signal in order to generate useful information from the signal. This F.M. receiver is designed using single IC used to receive frequency range of 88 MHz to 108 MHz in F.M. band,  it is built around TDA7000.

The TDA7000 is a monolithic integrated circuit for mono FM portable radios, where a minimum on peripheral components is crucial. The IC TDA 7000 has a Frequency-Locked-Loop system with an intermediate frequency of 70 kHz. The intermediate frequency selectivity is achieved by active RC filters. The only function which needs alignment is the resonant circuit for the oscillator, thus selecting the reception frequency. Spurious reception is avoided by means of a mute circuit, which also eliminates too noisy input signals. Special steps are taken to meet the radiation requirements.

CHAPTER ONE

1.1                                                          INTODUCTION

An fm receiver (commonly also called a radio) is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves (electromagnetic waves) and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.

The information produced by the receiver may be in the form of sound. A radio receiver may be a separate piece of electronic equipment, or an electronic circuit within another device.

In consumer electronics, the terms fm receiver are often used specifically for receivers designed to reproduce the audio (sound) signals transmitted by radio broadcasting stations, historically the first mass-market commercial radio application.

1.2                                             OBJECTIVE OF THE PROJECT

The objective of this work is to design receives radio frequency signal from an antenna in order to produce usable information such as audio. It is designed using single IC used to receive frequency range of 88 MHz to 108 MHz in F.M. band,  it is built around IC TDA7000

1.3                                          SCOPE OF THE OF THE PROJECT

An fm receiver consisting of an antenna, a variable inductor, and filter capacitors. fm receiver radio uses no active parts: it is powered only by the radio signal itself, whose detected power feeds headphones in order to be audible at all. In order to achieve even a minimal sensitivity, a fm receiver is limited to low frequencies using a large antenna (usually a long wire). It relies on detection using some sort of semiconductor diode such as the original discovered long before the development of modern semiconductors.

To operate the radio receiver, potentiometer VR1 must first be advanced slowly (towards the end of the track connected to battery positive) until, at about the half-way point, a sudden slight increase in background noise will be heard, indicating the onset of oscillation. It then should be backed off, very slowly, until oscillation just stops; it then should be possible to tune in some stations.

The correct frequency range of 87 MHz to 108 MHz can be obtained by adjusting VC2 at the high frequency (108 MHz) and slightly stretching or squeezing together the turns of coil L1 at the end (87 MHz).

1.4                                         SIGNIFICANCE OF THE PROJECT

This fm receiver includes simple transistor radios that are typically monoaural and receive the FM. This device is simple, easy-to-make.

Radio is a popular medium for people at home or on the move. Radio remains a strong advertising medium with continued growth in advertising revenue, according to the Radio Advertising Bureau. The Bureau’s membership includes more than 6,000 radio stations in the U.S. offering advertisers a choice of local, regional and national coverage. The availability of radio on mobile devices such as smart phones with Internet connectivity gives advertisers access to a new mobile audience, as well as the traditional audience at home, at work or in cars.

Local

For small businesses, radio represents a powerful local medium. Local radio attracts an audience that wants to keep up with local news, events and personalities. Businesses with a focus on local audiences led the growth in spot radio advertising in the third quarter of 2011, according to the Radio Advertising Bureau. Auto dealers and restaurants took the first two places with entertainment venues and home furnishings figuring in the top six.

Coverage

Radio enables small business to match advertising campaigns with their geographical markets. Local businesses can use local or regional stations to reach local customers, while small businesses targeting national markets can advertise on national radio. Using national radio in conjunction with an e-commerce website means that small businesses do not have to build a network of outlets to reach a national audience.

Special Interests

Radio stations target different audiences with their programming schedules, enabling advertisers to target special interest groups or different age groups with minimal waste. Different music programs, for example, give you the choice of targeting a teenage audience, an older audience with an interest in classical music or cultural events, or a general audience.

Cost

Radio advertising is a low-cost medium compared with rates for reaching similar audiences by press or television advertising. Rates vary by region with higher costs for radio stations that cover densely populated metropolitan areas. Production costs are lower than those of other media. You can create simple radio ads yourself or use a production company to create more complex ads. Some radio stations offer free or low-cost production services to advertisers.

Trust

Radio advertisements reach an audience that trusts the medium for information such as news, weather and sports reports. Radio also plays an important emotional role in listeners’ lives, according to the UK Radio Advertising Bureau. People listen to radio when they are getting ready in the morning, doing household chores or traveling, creating an advertising environment that other media cannot match

Attention

The emotional strength of radio can also be a disadvantage for advertisers. Radio can provide a background sound for people who are working, traveling or carrying out chores, which means they are only paying partial attention to content and may miss advertising messages. Advertisements that use only voice or voice and music can blend in to general program content, minimizing their impact.

1.5                                           LIMITATION OF THE PROJECT

• Insensitive, it needs a strong RF signal and/or a long-wire antenna to operate.
• Poor selectivity since it only has one tuned circuit.
• Low battery can affect the frequency
• The oscillator is adjusted between 87 and108 MHz with C5. Because of the synchronization, the oscillator output will have the same frequency deviation as the received signal from the fm antenna.