ABSTRACT
The early radio transmitters were so large and unwieldy that they took up a lot of room. The valves that are used in the circuits are typically large in size.
Electronic equipment is getting miniaturized as a result of the introduction of semiconductor materials such as transistors, resulting in small transmitters that are convenient and compact.
As a result, we decided to design a comprehensive radio broadcasting system that is both tiny and uses semiconductor materials.
The system units are divided into two groups: A condenser microphone is used to process and mix musicals on an audio console. The center frequency is provided by the transmitter unit. All of these were created to be tiny and portable. This project aims to serve a community with a small and compact radio broadcasting equipment with a power watt of 1 watt. A community of 1 kilometer in radius should be comfortably served, and the audio production should be very clear, unlike the typical noisy FM microphone project.
INTRODUCTION
The goal of this project is to develop and build a comprehensive radio broadcasting system that is tiny and downsized. It has a power output of 1 watt and is capable of covering a distance of 400 meters, or 200 meters depending on obstructions.
The frequency of the transmitted signal remains constant and fluctuates in response to the amplitude variations of the audio input. When the amplitude of the input signal increases (i.e. during the positive half cycle), the carrier frequency increases as well; on the other hand, when the amplitude of the input signal declines (negative half-cycle or no signal), the carrier frequency lowers.
CHAPTER ONE
MODULATION TYPES AND FUNDAMENTALS OF TRANSMITTERS
THE ESSENTIALS OF A TRANSMITTER
Because the AM transmitter generates such a large amount of power, efficiency is a must. Amplitude modulation can be generated at any point after the radio frequency source; in fact, a crystal oscillator might be amplitude modulated if the frequency stability of the crystal oscillator was not compromised. When a transmitter’s output stage is plate modulated, the system is referred to as high-level modulation.
A stable RF source and buffer amplifier are followed by an RF power amplifier in an AM transmitter, which can be low level or high level modulated. The audio voltage is treated or filtered to fill the appropriate bandwidth and compressed to minimize the maximum ration.
The primary requirement of an FM system in an IM transmitter is a changeable output frequency that varies proportionally to the instantaneous amplitude or modulation voltage.
The power and auxiliary stages of an FM transmitter are similar to those of an AM transmitter, with the exception that because FM is a constant amplitude modulation system, all of the power amplifiers can be run in class c, which saves energy.