Introduction

In the vast landscape of technological advancements, few inventions have had as profound an impact on communication as radio. The ability to transmit and receive information wirelessly has not only revolutionized the way we access news and entertainment but has also played a pivotal role in connecting the world. This blog explores the fascinating history of radio broadcasting, delving into the principles of transmission and reception that have shaped this transformative medium.

A split image shows a modern radio studio mixing console with headphones on the left, and a vintage transistor radio on a wooden table on the right.

Broadcasting is the process of sending radio or TV signals from an antenna to multiple receivers that can pick up the signal simultaneously. In simple terms, broadcasting means “to radiate radio waves from a station into space” or “to send signals in all directions.” Once the waves are sent into space, transmission begins, and all receivers within range can pick up the signal at the same time. This is called reception. While broadcasting and transmission are closely related, they are slightly different processes, and reception is quite different from both. Important components of a typical network are shown below.

Diagram illustrating radio broadcast transmission and reception process. Sound is captured by a microphone, amplified, and modulated. It is transmitted via an antenna as radio waves, received and detected, then output as sound.

1.Broadcasting

Microphone: At the broadcasting station, the person speaks before mike. The mike is a transducer and converts sound energy into electrical energy. The speaker generates a sound of frequency between 20 Hz and 20 kHz (i.e., audio frequency).
Amplifier: The electrical signal obtained from microphone (mike) is weak and the same is amplified through an amplifier(s) to the required strength.
Modulator: Here, the signal undergoes modulation. A local oscillator generates high-frequency waves called the ‘carrier’. The signal modulates the carrier, or you can say the signal is superimposed on the carrier. The resulting waves are called radio waves or modulated waves.
Transmitting antenna: Through the transmitting antenna, the radio waves are propagated into the space.

2. Transmission

After broadcasting, transmission begins. These radio waves, being electromagnetic waves, travel through space at a speed of $\times 10^8$ m/s.

3. Reception

The picking of these radio waves by radio (or T.V.) receiver is called reception. A radio receiver has the following important parts:

Receiving antenna: The radio waves induced an e.m.f. on the antenna.
RF amplifier: The radio waves are of radio frequency (R.F.) range. The e.m.f. induced is amplified through R.F. amplifier(s).
Detector: Now the original signal is detected (separated) from the carrier by the detector circuit.The signal starts its forward journey while the carrier is grounded.
A.F. amplifier: The signal is now passed through the amplifier.Note that now the signal is of audio frequency range. It should have sufficient energy to strike the loudspeaker.
Loudspeaker (L.S.): This is the final stage. The electric signal is again converted into the original sound signal which was produced in the broadcasting station:

Note:

Here ‘Radio’ does not mean radio receiver. The ‘radio’ means wireless.
Radio means ‘radiations for wireless transmission’.The principle of radio broadcasting,transmission and reception described above is same for radio,T.V. signals and also for all such wireless devices.
Radio is the abbreviated form of ‘radio telegraph or radio telephone.
Broadcasting means to ‘send out’ in all directions. It may be:

A.M. radio broadcast band: Its range is 540–1600 kHz. The stations are assigned every 10 Hz in the above band.
F.M. radio broadcast band: Its range is 88–108 MHz. The stations are assigned every 200 Hz in the above band.
T.V. broadcasting band: A T.V. channel is 6 MHz wide to include picture and sound signals for each broadcast station.

5.Analog and digital broadcast signal

Analog form of a broadcast signal is a continuous variation as shown in Fig. 1 (a),
Digital form of broadcast signal is shown in Fig. 1 (b).

Alt text: "Comparison of analog and digital signals. Image (a) shows a smooth, continuous wave representing an analog signal. Image (b) depicts a blocky, step-like pattern with labeled 'High (1)' and 'Low (0),' illustrating a digital signal."

Figure 1

REASONS OF ERRORS IN COMMUNICATION SYSTEM

We say an error has occurred when the received message becomes distorted. The distortion may be a frequency, phase or any other distortion.

There are following reasons which produce errors:

Band Width: Insufficient bandwidth during transmission causes errors. AM transmission gets only 10 kHz of bandwidth, while the human ear needs 15 kHz for full audio satisfaction. As a result, AM transmission lacks fidelity. In contrast, FM transmission uses 200 kHz of bandwidth, allowing it to reproduce the transmitted signal with full audio quality.
Noise: We call unwanted sound "noise," and it is another factor that causes errors. Noise can be external or internal. You can improve the signal-to-noise ratio by adjusting the bandwidth.

TYPES OF COMMUNICATION SYSTEMS

The electronic communication systems according to medium are of following types:

Wire communication: i.e., Wired communication uses physical wires for transmission, such as in cable TV and wire telephony. These wires may consist of galvanised steel (see Fig. 2).
Wireless or carrier communication: i.e., Wireless communication allows transmission without wires. In this system, the setup uses a carrier wave. In other words, the system modulates the carrier, as seen in radio, TV, radar, and telephony. A carrier is a high-frequency wave that carries the signal by having the signal superimposed on it (see Fig. 3).
Optical fibre communication: An optical fibre cable (OFC) has an inner glass core surrounded by glass cladding and a protective covering (Fig. 4). The system transmits digital signals as intensity-modulated light signals trapped within the glass core. A photo device on the other end detects the signal. Engineers use this type of communication at frequencies above $10^{10}$ Hz.
Satellite communication: In this system, a satellite positioned in space transmits and receives the signals..
Wave guide communication: This communication system uses waveguides for signal transmission. Engineers use them for frequencies between $10^{8}$ and $10^{10}$ Hz.
Co-axial cables communications: Engineers use co-axial cables for frequencies between $10^{5}$ and $10^{8}$ Hz.

A diagram shows a telephone pole with three parallel lines labeled "Telephone wire" and an upward-pointing arrow. Black lines on a white background.

Figure 2

Block diagram illustrating signal processing. A signal and carrier input into a modulator, then to a transmitter, with an arrow indicating output.

Figure 3

Diagram of a fiber optic cable showing three layers: the inner glass core, middle glass cladding, and outer protective covering, each labeled.

Figure 4

We can also classify communication as analog and digital. In analog communication, the system modulates and transmits the signal directly.

In digital communication, the system converts the analog signal into a digital signal before transmission. See Fig. 5.

Diagram illustrates signal conversion: "Analog Signal" to "Digital Signal" via sequential steps: Sampling, Quantizing, and Encoding, linked by arrows.

Figure 5

The Birth of Radio Broadcasting:

Firstly, the story of radio begins with Marconi and Tesla. Indeed, Marconi's wireless telegraphy marked radio’s birth. Furthermore, it enabled global communication, consequently inspiring innovation. Therefore, broadcasting evolved, additionally gaining interest. Moreover, it connected communities, thus shaping culture. Meanwhile, in the 1920s, radio grew, since pioneers like De Forest and Armstrong developed audio transmission. Similarly, technology advanced, hence expanding reach, besides enriching society, ultimately transforming communication.

Principles of Transmission

1.Electromagnetic Waves

Therefore, radio transmission utilizes electromagnetic waves. The waves propagate at the speed of light that allows to transmit information for long distances without using wires. Radio frequencies, measured in hertz (Hz), determine the wavelength of a signal and the distance it can travel.

2.Modulation

To modulate is the process through which radio waves transfer audio information. Engineers use two major processes: amplitude modulation (AM) and frequency modulation (FM).In AM, the amplitude of the carrier wave changes to carry the signal. In FM, the frequency of the carrier wave adjusts to carry the signal. FM provides better sound quality, which is why it has overtaken most music and voice communications.

3.Transmitters

Radio transmitters change audio signals into radio waves. Such doing devices, starting from broadcast posts to complete stations significantly boost and transmit signals over a cleanup frequency; all communications share the appropriate target.

Principles of Reception

1.Antennas

The reception of radio signals significantly depends on antennas. This equipment picks up electromagnetic waves and converts them back into electrical signals, which the radio receiver can then process.

2.Radio Receivers

Radio receivers used in radios and car stereos, pick specific frequencies by tuners which users can select. The receiver demodulates the signal to restore the original audio, which you can then reproduce through a speaker or headphones.

3.Demodulation

The demodulation process is reciprocal to the modulation applied in transmission, hence restoring the pristine audio signal. This enables the listeners to listen clearly and in a digital form.

4.Radio's Impact on Society

The invention of radio broadcasting triggered a communication revolution radically changing the way people get and make use of information. In the golden age of radio, with magical dramas performed live by celebrities to current-day podcasts is very popular.

Conclusion

It is imperative that we recognize the significant influence of radio broadcasting on international communication as we navigate the digital era. Firstly, radio remains a dynamic force in media because its principles have indeed withstood time. Furthermore, they have also developed. In fact, radio connects people, consequently enabling global communication, therefore staying relevant. Additionally, it adapts, moreover embracing digital tools, thus remaining current. Meanwhile, as tech evolves, since needs grow, hence radio integrates innovations. Similarly, it aids education, besides entertainment, ultimately reaching many. Nevertheless, challenges arise; however, radio overcomes them. Likewise, it inspires, accordingly shaping culture. Otherwise, voices go unheard. Finally, when you tune in, pause to recognize radio’s marvel and history.

All about Radio (wireless) broadcasting,Transmission and reception