DRM, DAB, or HDRadio: Which Digital Standard for Brazil?
- Ricardo Gurgel
- 26 de abr.
- 6 min de leitura
Atualizado: 11 de mai.
Comparing Digital Radio Systems for Brazil
The major digital radio systems worldwide are DAB, HD Radio, and DRM. Experiments are taking place across the globe, aiming either to select one standard or to adopt a composition of standards divided by frequency bands. Choosing a standard impacts an entire industry that moves billions of dollars, with fierce competition among major players in the leading markets.
Related post: Brazilian Engineer Ricardo Gurgel: In Brazil, digital radio will start on AM https://www.blogdorg.com.br/post/brazilian-engineer-ricardo-gurgel-in-brazil-digital-radio-will-start-on-am
What's at stake?
Imagine tuning into radio stations with pristine audio quality — pure excellence for the ears — along with visual information on the screen, emergency alerts, and various other services integrated into a digital broadcast. Digital audio is vastly superior — addictive even — and essential for equipping radio broadcasters already competing with digital platforms on the internet.
Let’s move on to the comparisons.
Standard | DRM |
Operating Bands | AM, VHF (FM), and bands above 30 MHz |
Standard | HDRADIO |
Operating Bands | AM and FM |
Standard | DAB |
Operating Bands | Primarily Band III (VHF) and L-Band |
Regarding operating bands, DRM is the most comprehensive, being the only standard that also covers shortwave bands.
Related post: Is India Eyeing Brazil to Implement Digital AM through DRM? https://www.blogdorg.com.br/post/ricardo-gurgel-is-india-eyeing-brazil-to-implement-digital-am-via-drm
Standard | DRM |
Transmission Modes | Digital or hybrid |
Standard | HDRADIO |
Transmission Modes | Digital or hybrid |
Standard | DAB |
Transmission Modes | Digital-only |
Alert:
While hybrid transmission (analog + digital on the same channel) might seem advantageous, history shows that the more analog consumption is preserved, the more issues arise: greater interference, increased technical complexity, and higher costs — all leading to a slower adoption rate.
Without a doubt, the best strategy for broadcasters is to maintain analog transmissions on one frequency and digital transmissions on another, free from power and bitrate limitations.
Standard | DRM |
Data Rates and Spectral Efficiency | Data Rate: 4.5 to 186 kbps (depending on band and mode)Spectral Efficiency: High (adjustable based on bandwidth) |
Standard | HDRADIO |
Data Rates and Spectral Efficiency | Up to ~150 kbps on FMSpectral Efficiency: Medium (dependent on analog channel constraints) |
Standard | DAB |
Data Rates and Spectral Efficiency | ~64 to 256 kbps (per service/program)Spectral Efficiency: High (multiple channels multiplexed) |
Data rate simply translates to the potential quality of the broadcast: the higher the bitrate, the better the audio quality and the more services can be integrated.
DAB stands out with extremely high audio quality and excellent frequency utilization, allowing more stations and simultaneous programs with great flexibility.
DRM is excellent for revitalizing underserved bands, such as shortwave and AM.
DAB is also ideal for the "signal chaos" found in large cities, where competition among broadcasters and demand for superior audio quality are extremely high.
Standard | DRM |
Coverage Comparison | Better than analog AM/FM, but variable depending on conditions |
Standard | HDRADIO |
Coverage Comparison | Similar to analog |
Standard | DAB |
Coverage Comparison | Excellent for urban and suburban areas |
Coverage Comparison
Standard: DRM (Digital Radio Mondiale)Coverage: Better than analog AM/FM, but variable depending on conditions
Standard: HD RadioCoverage: Similar to analog
Standard: DAB (Digital Audio Broadcasting)Coverage: Excellent for urban and suburban areas
I see no obstacles to adopting DRM (Digital Radio Mondiale) as a solution for modernizing various shortwave and AM bands that are currently underserved. Likewise, DAB (Digital Audio Broadcasting) is ideal for large cities plagued by signal congestion due to high station density and competition for the best audio quality. I do, however, have reservations about HD Radio, especially because of its hybrid nature, which faces challenges with interference from signal sharing on the same channel. Therefore, I advocate that both HD Radio and DRM, if applied to the AM band, should operate exclusively in fully digital mode.
Multiprogramming Capabilities
Standard: DRM (Digital Radio Mondiale)Multiprogramming: Flexible (1 to several programs)
Standard: HD RadioMultiprogramming: Limited (2–4 streams)
Standard: DAB (Digital Audio Broadcasting)Multiprogramming: High (multiple programs per multiplex)
Imagine a significant increase in the number of radio stations available via DAB, or a single broadcaster transmitting multiple distinct and simultaneous programs — this is a major advantage offered by DAB. DRM also offers some flexibility in this regard, while HD Radio supports multiprogramming but is the most limited among the three systems.
Global Popularity
Standard: DRM (Digital Radio Mondiale)Global Reach: India, parts of Europe, Russia
Standard: HD RadioGlobal Reach: United States and Mexico
Standard: DAB (Digital Audio Broadcasting)Global Reach: Europe (United Kingdom, Norway, Switzerland)
Audio Quality Summary
DRM (up to 186 kbps) and DAB+ (up to 256 kbps) provide better audio quality than HD Radio.
DAB+ (the latest version of DAB) transmits audio using HE-AAC v2, delivering CD-like or superior quality at lower bitrates (~64–128 kbps per channel).
DRM also offers excellent audio quality (up to CD level) and is very flexible, allowing configuration for either higher quality or greater coverage.
HD Radio provides good FM quality (similar to CD, though compression artifacts can sometimes be noticeable), and significant improvements for AM (bringing it close to FM analog quality), but it still relies on a hybrid structure that limits its full potential.
Digital Radio Aims to Reduce Signal Failures and Improve Reception in Cities.
THE MULTIPATH EFFECT: In analog FM (our current system), this effect can result in sound distortions, such as hiss, crackling, or even momentary signal loss, especially in densely populated urban areas or mountainous regions. |
In analog FM (our current system), this effect can result in sound distortions, such as hiss, crackling, or even momentary signal loss, especially in densely populated urban areas or mountainous regions.
It is an interference phenomenon caused by the reception of a radio signal via multiple paths. This happens when the signal transmitted by a station reaches the receiver (such as a radio) through different trajectories due to reflections off obstacles like buildings, mountains, trees, or other surfaces.
How it works:
Multiple paths: The radio signal can travel directly from the transmitting antenna to the receiver (direct path) or be reflected by surfaces, creating indirect paths.
Delay and phase: Reflected signals arrive at the receiver with slight delays and may be out of phase with the direct signal. This causes interference, as the signals may combine (constructive interference) or cancel each other out (destructive interference).
DAB has a solution:
In DAB (Digital Audio Broadcasting), the multipath effect not only causes less disruption, but it was anticipated in the system’s design. In fact, DAB was developed to perform exceptionally well in environments with multipath, such as urban centers filled with buildings, mountains, tunnels, etc.
In simple terms:
DAB uses a technique called OFDM (Orthogonal Frequency Division Multiplexing), which splits the signal into multiple small, spread-out carriers.
When multipath occurs (signal reflected via multiple paths), these carriers can intelligently recombine at the receiver, automatically correcting what would be errors in analog systems or other digital formats.
This transforms multipath, which would be a significant issue in analog FM (hiss, ghosting, fading), into an advantage, as the reflected signal helps reinforce the total captured signal.
In summary, with DAB, the multipath effect does not hinder performance; it is tolerated and even leveraged to improve reception. This makes DAB ideal for densely populated urban areas.
DRM does too:
DRM was designed with technologies that minimize the disadvantages of the multipath effect, such as COFDM modulation, guard intervals, and robust coding. These features make it a far more effective solution than analog FM in environments prone to reflections, such as urban areas or mountainous regions.
As for HD Radio...
HD Radio offers protection against the multipath effect through COFDM, guard intervals, and error coding, but its effectiveness is limited, particularly in hybrid mode, due to interference between analog and digital signals and less flexibility compared to systems like DRM. In environments with intense multipath, HD Radio may face more challenges, and its performance heavily depends on the quality of the receiver and the transmission setup.
This video was released on YouTube in February 2021 from the Antenna Man channel, titled "HD Radio - Extra Digital AM/FM Radio Stations in Your Area." It discusses how HD Radio was nearing its 20th anniversary at the time, now approaching 25 years, and its relatively low penetration in the US. Even Americans are critical of the system, which is expensive for broadcasters to adopt and costly for consumers to purchase compatible, limited equipment.
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