1.1 Introduction
Frequency Modulation (FM) is that type of modulation in which the frequency is varied in linearly with a message or baseband signal about a modulated carrier frequency. Broadcast band frequency modulation (FM) receiver came into existence as a substitute and alternate to amplitude modulation (AM) broadcast band which has the problems of noise and fidelity. The modulated signal is received through the receiving antenna from the medium and then applied to the FM receiver where the signal frequency is demodulated. Then the original electrical signal is inverse transduced by the output transducer like amplifier box, speakers etc. which converts the electrical signal into sound or it can be further processed (Moumita and Rumpa, 2015).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Receiver is generally an electronic equipment that accepts, transforms and outputs an enveloped signal into a form that could be noticeable and meaningful to human senses. A radio receiver is therefore the one that will output an audible sound signal for human usage. A radio receiver must perform a number of functions. First, it must radio signals. It will then amplify the wanted signal to a usable level. Finally, the receiver must recover the information signal from the radio carrier and pass it on to the user via a speaker. Hence an FM receiver is a receiver that decodes a required frequency modulated (FM) radio signal from among group of signal.
The essential process involve in FM receiver operation is demodulation or detection of an already frequency modulated signal. FM receiver employ a special detector for FM signals and exhibit a phenomenon called capture effect, where the tuner is able to clear and receive the stronger of two stations being broadcast on the same frequency. As a common problem, frequency drift or lack of selectivity may cause one station or signal to be suddenly overtaken by another on adjacent channel selectivity.
Compared to AM receiver, FM receiver has some advantages. The signal-to-noise ratio can be increased without increasing transmitted power rather at the expense of an increase in frequency bandwidth required; interference are more easily suppressed and modulation process can take place at low –level power stage in the transmitter, thus avoiding the need for large amounts of modulating power.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to Design and Construct a Frequency Modulation (FM) Receiver.
1.3 Statement of Problems
Investigation reveals that FM receivers are however a complex equipment demanding high power supply, high voltage system design, critical maintenance and exorbitant price. These problems of the FM receiver constitute major impediments to institutions and individuals that may wish to adopt radio broadcast as means of electronic media.
These problems of the FM receiver constitute major impediments to individual and institution that may wish to adopt radio broadcast as means of electronic media. The private individual and organizations lack resources to purchase and maintain complex transmitting plant whose price is exorbitant and requires critical maintenance.
1.4 Aim and Objectives of Study
The aim of the study is to Design and Construct a Frequency Modulation (FM) Receiver. In achieving this aim, the following specific objectives were laid out as follows:
- To understand the underlying principle of FM demodulation.
- To design and construct an FM radio receiver.
- To provide adequate knowledge of signal reception which is an important process in telecommunication.
- To put into practice, the practical and theoretical skill acquired in circuit and components designed and analysis.
1.5 Significance of Study
This study will be of immense benefit to engineering students and other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The scope of the research is focused on the Design and Construction of Frequency Modulation (FM) Receiver.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.8 Definition of Terms
Modulation: This is the process of combining an audio frequency (AF) signal or the modulating wave with a radio frequency (RF) carrier wave. The resultant wave produced is called modulated wave.
