In the era of digital technology and streaming audio, many believe that terrestrial radio broadcasting has sunk into oblivion, giving way to streaming services. However radio waves have not disappeared anywhere, they have simply transformed and continue to be the main source of operational information for millions of drivers and residents of remote areas. The question of which wave is used in modern radio is no longer unambiguous, since today several signal transmission standards coexist.
It is important for a driver or technician to understand the difference between analog and digital bands in order to properly configure the receiving equipment in a car or home receiver. Frequency range determines not only the sound quality, but also the signal propagation range, as well as resistance to interference. In this article, we will examine in detail the physical principles of operation of different waves, their advantages and disadvantages in the modern communications landscape.
Despite the active introduction of digital standards, the good old frequencies have not gone away. Moreover, in emergency situations, it is the protozoa AM/FM receivers often remain the only working means of communication. Understanding how these waves work will help you make the right equipment choices and set them up for ideal reception anywhere along your route.
Analog Legacy: AM and FM Bands
Traditional radio broadcasting is based on two main types of modulation: amplitude modulation (AM) and frequency modulation (FM). Amplitude modulation, operating in the long (LW), medium (MW) and short wave (SW) bands, has historically become the first mass-produced sound transmission technology. A signal in this range bends around the earth's surface and is reflected from the ionosphere, which allows it to spread over thousands of kilometers, especially at night.
On the other hand, ultrashort waves (VHF), known to us as the FM band (87.5–108 MHz), provide significantly higher sound quality. However, the physics of the propagation of these waves is such that they practically do not bend around obstacles and act within the line of sight. This is why covering one area requires many repeaters operating at different frequencies to avoid interference.
When setting up a car antenna, make sure that the signal booster is activated in the radio menu if you are in an area with poor FM signal reception.
It is important to note that the quality of FM radio reception is highly dependent on the terrain and the presence of high-rise buildings. While an AM signal may make it through a tunnel or over-the-horizon area, an FM wave will simply disappear, replaced by static noise. This fundamental difference dictates the choice of equipment: for long trips on highways, receivers with support medium waves.
Digital revolution: DAB+ standard and its features
Modern radio is not only analog, but also an active transition to digital. Standard DAB+ (Digital Audio Broadcasting) is a technology for transmitting audio signals in digital form. Unlike FM, where each station is allocated a separate frequency, digital broadcasting uses the principle of multiplexing: a package of several radio stations is transmitted simultaneously in one frequency channel.
The main advantage of DAB+ is the absence of characteristic noise and hiss that accompany a weak analog signal. A digital receiver either receives the signal perfectly cleanly or does not receive it at all - there is no “smooth fading” effect here. A codec is used to encode audio AAC+, which at a low bitrate provides better quality than traditional FM broadcasting.
Why does digital radio end in "silence"?
Unlike an analog signal, which gradually turns into noise as it moves away from the transmitter, the DAB+ digital stream has a threshold value. If the signal level drops below a critical minimum, the decoder stops restoring data and the sound simply disappears. Engineers call this phenomenon a “digital cliff.”
However, the implementation of this standard faces the need to replace the receiver fleet. Old radios, even those released 5-7 years ago, may not support the DAB+ format, requiring the installation of an external tuner or replacement of the head unit. However, spectral efficiency digital broadcasting makes it the future of radio communications in developed countries.
Internet radio: wave without borders
When we talk about the wavelength of modern radio, we cannot ignore the fastest growing segment - Internet broadcasting. Here the physical radio wave gives way to packet data transmission through networks 3G/4G/5G or Wi-Fi. In fact, the “wave” becomes a stream of bits passing through the provider’s servers, which removes any geographical restrictions.
The user can listen to the radio station from any corner of the planet, having only a network connection. The sound quality in this case is limited only by the channel bandwidth and can reach studio standards without compression. Modern automotive systems with support Android Auto and Apple CarPlay They actually turn your smartphone into a powerful Internet radio receiver.
- 🌍 Global coverage: access tens of thousands of stations from all over the world without switching frequencies.
- 🎵 High bitrate: the ability to transmit HD audio without compression artifacts.
- 📉 Dependency on traffic: consumption of mobile traffic and the need for network coverage by the operator.
- ⏳ Signal delay: latency during Internet broadcasting can reach 30-60 seconds compared to broadcasting.
Despite the obvious advantages, Internet radio has a critical drawback for motorists - dependence on cellular network coverage. In remote areas, where the good old FM receiver can reliably pick up, the smartphone may show “No network”. Therefore hybrid solutions, combining an over-the-air tuner and an Internet module, are becoming the gold standard in the auto industry.
Comparison table of radio wave characteristics
To systematize information about different types of broadcasting, let's consider their key parameters in comparison. This will help to understand why omnivorous tuners that support multiples standards are often installed in a modern car or home system.
| Parameter | FM (VHF) | AM (NE/LW) | DAB+ (Digital) | Internet |
|---|---|---|---|---|
| Frequency range | 87.5 - 108 MHz | 0.5 - 30 MHz | 174 - 240 MHz | Not applicable |
| Sound quality | Average/Good | Low (mono) | High (stereo) | Excellent (HD) |
| Reception range | Up to 100 km | Up to 1000+ km | Up to 100 km | Globally |
| Interference immunity | Average | Low | High | Network dependent |
As can be seen from the table, each method has its own niche. Analog signal wins in simplicity and range (for AM), digital – in the quality and quantity of channels, and the Internet – in content. The choice of the “best wave” depends solely on the user’s tasks and listening geography.
Physics of propagation: why the signal disappears
Understanding the physics of the process helps explain why radio reception is excellent in one place, but interference begins a hundred meters later. Wavelength directly affects its ability to avoid obstacles. Long and medium waves (AM) range from tens to hundreds of meters in length, allowing them to easily wrap around hills and buildings, acting like water flowing around a rock.
Short FM waves (about 3 meters) behave differently - they are more like light. If an obstacle appears in the path of the wave (mountain, dense buildings, tunnel), a “radio shadow” is formed. That is why in cities with high-rise buildings, areas often arise where reception is impossible even with a powerful transmitter nearby.
⚠️ Attention: Metal structures of bridges and tunnels completely shield the FM signal. Unlike AM waves, which can partially penetrate such barriers, the VHF range is tightly blocked.
In addition, the quality of reception is affected by the weather, although to a lesser extent than for shortwave communications. Heavy rainfall can attenuate (weaken) the signal, especially in the upper frequencies of the range. Modern receivers use systems RDS (Radio Data System), which allow you to automatically switch to a frequency with a stronger signal of the same station, minimizing discomfort for the listener.
Practical setup and selection of equipment
When choosing a modern radio or head unit for a car, you should pay attention to support for current standards. If you often travel around the country, having a high-quality FM tuner with RDS remains mandatory. For urban use, the DAB+ module is becoming increasingly relevant, which requires the installation of a special active antenna.
The setup process for digital reception is different from analogue. Instead of searching for frequencies manually, the device performs scanning multiplexes. The user needs to start searching for channels, and the tuner itself will save the available stations into memory. It is important to ensure good contact of the antenna cable, since the digital signal is more critical to path losses.
☑️ Digital radio readiness check
Hybrid options should not be discounted either. Many modern systems allow you to broadcast sound from your phone (Bluetooth/AUX) simultaneously with the radio. This makes it possible to listen to your favorite FM station, and when leaving the coverage area, automatically switch to a streaming service, maintaining continuity of broadcasting.
The ideal car audio system today is a hybrid that supports FM, DAB+ and internet streaming, ensuring access to content in any environment.
The future of radio broadcasting: development prospects
Technologies do not stand still, and the next generation broadcast systems are already being tested. IP-based radio is becoming a dominant trend, where the broadcast network is used only as a backup channel or for transmitting critical messages (for example, storm warnings), which are duplicated in the digital package.
The concept of “hybrid radio” is developing, where the receiver itself decides which signal source to use at a given moment to ensure the best quality. If you are driving on the highway, the over-the-air tuner works. We drove into a city with good 5G - the device, unnoticed by the user, switched to a high-definition Internet stream.
However, there are no plans to completely switch off analogue broadcasting in the coming years. FM remains the most reliable means of communication in emergency situations when cellular networks may be overloaded or damaged. Therefore, the question “which wave” remains relevant: we need all waves at once.
Do I need to buy a new antenna for DAB+?
Yes, a regular telescopic or standard car FM antenna will not work to receive a DAB+ digital signal. You will need a special active antenna tuned to band III (174-240 MHz). Often such antennas have a combined output (FM+DAB), which allows you to use one cable.
Why does my car radio wheeze when driving under a bridge?
This is a classic example of the formation of “radio shadow”. VHF waves (FM) travel in a straight line and do not bend around massive concrete obstacles. The signal is reflected or absorbed and the receiver loses the carrier frequency. With digital radio (DAB+), you would either hear clear sound or there would be complete silence.
Can a magnetic field move a radio?
Yes, your vehicle's ignition system and alternator create electromagnetic interference, which is especially noticeable on the AM band. Modern receivers have noise reduction filters, but if spark plugs or high-voltage wires are faulty, background crackling can become audible even at FM frequencies.