The day was proclaimed by UNESCO in 2011 and later adopted by the United Nations General Assembly in 2012 (A/RES/67/124.
Radio remains a powerful medium, celebrating humanity in all its diversity while serving as a platform for democratic discourse.
It continues to be the most widely consumed medium globally, making it an essential tool for reaching diverse audiences, amplifying voices, and fostering inclusion.
But, what are AM, FM, Shortwave and Digital Radio?
AM Radio
AM, short for
Amplitude Modulation, refers to the way audio signals are encoded onto a
carrier frequency.
In many countries, AM radio stations are known as mediumwave stations. They were the first to broadcast public radio signals, earning them the title "standard broadcast stations."
AM radio transmits audio information by varying the amplitude (strength) of a signal while keeping its frequency constant. Imagine a steady signal at 1,000 kHz—until modulated with voice or music, it produces only static. The modulation process causes the amplitude to fluctuate in proportion to the sound being transmitted.
AM radio operates on a range of frequencies that vary by
country and region. These frequencies are known as carrier frequencies, which
deliver signals from broadcast antennas to radio receivers.
Advantages and Limitations of AM Radio
Long-distance transmission: AM waves can travel vast distances by bouncing off the ionosphere, allowing signals to be received hundreds or even thousands of miles away.
Simple and cost-effective: AM radio receivers require less complex circuitry than FM receivers, making them more affordable and accessible.
Prone to interference: AM signals are highly susceptible to noise from electrical sources, thunderstorms, and other disruptions, which can cause static and distortion.
Lower sound quality: Compared to FM, AM radio has lower
fidelity, making it less ideal for music broadcasting.
FM Radio
FM, short for Frequency Modulation, encodes audio information by varying the frequency of the carrier wave while keeping the amplitude constant.
When an FM signal is modulated, its frequency shifts between high and low, transmitting music or voice with greater clarity.
FM operates in a higher frequency range than AM, typically
providing stereo broadcasts with significantly better sound quality.
However, FM signals are limited in range, usually covering less than 100 miles, and can be obstructed by physical barriers like buildings and hills.
Advantages and Limitations of FM Radio
Higher sound quality: FM signals produce clearer, high-fidelity sound, making them ideal for music and speech.
Less susceptible to interference: Unlike AM, FM is less affected by electrical noise or weather conditions.
Limited range: FM signals travel in straight lines,
requiring more transmission stations to extend coverage.
The Evolution of Radio: AM and FM in the Digital Age
In recent years, AM and FM radio have faced increasing competition from satellite radio, streaming services, and digital platforms.
Many traditional stations have struggled to retain listeners and generate revenue.
Despite this, AM radio remains a vital medium in rural areas where other forms of communication may be less accessible.
As technology evolves, new opportunities may arise for AM and FM stations to adapt and thrive in the digital era.
The Concept of Modulation
Modulation is the process of encoding information onto a radio wave to create a meaningful transmission.
Without modulation, a radio
signal would be nothing more than random noise.
There are two main types of modulation used in broadcasting: AM (Amplitude Modulation): Alters the strength of the wave. FM (Frequency Modulation): Alters the frequency of the wave.
Shortwave Radio
Shortwave radio operates within the high-frequency (HF)
band, typically between 3 to 30 MHz. Unlike AM and FM signals, shortwave
signals can bounce off the ionosphere, allowing them to reach distances far
beyond the visual horizon—a process known as skywave or "skip"
propagation.
Because of this, shortwave radio has historically been crucial for international broadcasting, emergency communication, and connecting remote areas.
However, its significance has diminished with the rise of satellite radio, internet streaming, and other modern technologies.
What is Digital
Radio?
Digital radio converts audio into binary code (digits) before transmission. Unlike analogue signals, which can suffer from distortion, digital signals offer clearer reception and higher sound quality.
Benefits of Digital Radio:
Better sound quality: FM digital radio delivers CD-quality sound, while AM digital radio rivals standard FM.
Additional audio channels: A single digital frequency can carry multiple programs.
Enhanced data services: Digital radios can display information like song titles, artist names, weather updates, and news alerts.
Simultaneous analogue-digital broadcasts: Many broadcasters offer both analogue and digital signals, making the transition to digital seamless.
How Digital Radio Works
Encoding: The transmitter converts sound into digital fragments (digits).
Transmission: The fragments are sent multiple times to improve reception reliability.
Reception & Assembly: The receiver collects and reconstructs the fragments to produce a continuous audio signal.
Unlike analogue signals, digital radio uses a much wider frequency band—about 1,500 times broader—which reduces interference and allows for multiplexing (simultaneously broadcasting multiple programs on a single frequency).
