Digital Radio Mondiale (DRM) is a digital broadcasting standard designed to replace traditional analog AM and FM radio with improved audio quality, efficient spectrum use, and enhanced data services. Developed to work across a wide range of frequencies, DRM is particularly effective for both long-distance and local broadcasting.
Technical Features of DRM
- Modes of Operation:
- DRM30: Operates on frequencies below 30 MHz (AM, longwave, shortwave) and is ideal for long-range broadcasting. This mode is particularly useful for reaching remote areas and ensuring global coverage.
- DRM+: Functions on frequencies above 30 MHz (FM band), providing high-quality, local digital broadcasts with near-CD audio quality.
- Spectrum Efficiency:
- DRM uses advanced modulation schemes like COFDM (Coded Orthogonal Frequency Division Multiplexing) and hierarchical modulation to pack more channels into the same bandwidth. This allows multiple stations to broadcast simultaneously on the same frequency.
- Audio Quality:
- DRM offers significant improvements over analog, with AM broadcasts achieving near-FM quality and FM broadcasts reaching CD-like sound quality. The use of AAC+ codecs ensures high fidelity even at lower bitrates.
- Data Services:
- DRM supports additional services such as Journaline (text), Slideshow (images), and EWF (Emergency Warning Functionality). These can be broadcast alongside the audio, providing listeners with real-time information and multimedia content.
- Energy Efficiency:
- DRM transmitters are more power-efficient than analog transmitters, reducing operational costs. This is particularly beneficial for broadcasters looking to modernize their infrastructure while maintaining or expanding coverage.
Cons of DRM:
- Adoption and Market Penetration: DRM has lower adoption rates compared to DAB (Digital Audio Broadcasting), especially in urban markets dominated by FM and DAB.
- Receiver Availability: Fewer consumer devices support DRM, limiting its accessibility.
- Infrastructure Requirements: Transitioning to DRM requires investment in compatible transmitters and receivers.
CML Micro has embraced DRM technology by building the DRM1000 broadcast receiver module that offers a ‘antenna-to-audio’ solution, tailored for integration by broadcast receiver manufacturers. It comes with complete software support, enabling top-tier reception of AM, FM, and DRM (both DRM30 and DRM+) broadcasts globally across MF, HF, and VHF (Bands I and II). The module’s software is designed to work with a straightforward user interface, using an affordable, small display and push-buttons.
The DRM1000 paired with CML Micros demonstration kit DE9180-2 allows the functionality of the DRM1000 AM/FM Broadcast Receiver Module to be easily demonstrated. The DRM1000 module is supplied soldered directly to the PCB, as it would be in an end-product.
The DE9180 offers an array of inputs, outputs, and controls to fully evaluate the performance of the DRM1000. It features an external power supply connector, a headphone jack, ports for connecting external HF/VHF and MF antennas, a built-in loudspeaker, a battery compartment, and a 16x2-character OLED display. Additionally, it comes equipped with a 12-button keypad, allowing users to adjust volume (up and down), select stations, switch frequency bands, access four preset station memory buttons, initiate frequency scans, and manage other user functions.
Summary
DRM offers a technically robust solution for modernizing radio broadcasting, especially in regions where long-distance coverage is essential. While it faces challenges in adoption compared to DAB, DRM’s ability to operate across multiple frequency bands, coupled with its efficient use of spectrum and energy, makes it a compelling choice for broadcasters looking to future-proof their services.