A Streamlined Approach to DRM Receiver Design An Article

Software Defined Radio (SDR) turns the hardwired, task-specific and very elaborate chip development of the past into a flexible software-based design running on a generic, efficient and mass-produced hardware platform. It is not a new concept, but it is becoming a reality in more and more technical systems. Digital radio receivers are one major example for SDR technology, because modern processor platforms offer enough computing power to build almost the complete radio functionality in software.

ADVANTAGES

This approach offers great advantages for both the radio architecture itself and the companies developing and using the radio receiver technologies. The software development becomes widely decoupled of the hardware development. The selection of software vendors is independent of the providers of the underlying hardware platform.

In some cases, it makes sense to optimize the software for processor families to reduce the overall system power and extend battery lifetime. Still, the well-tested and field-proven software that encapsulates all digital radio functionality can easily be ported to the next generation of hardware. Existing products can be enhanced to support future functional upgrades or even completely new radio standards.

Especially in the production chain of car radio systems, the selection of the final software components, which are typically dependent on the target market and required feature set, can be carried out at the end of the production line. This prevents the time-consuming need to swap hardware components, or the costs involved with provisioning multiple hardware options. Even after the shipment of a car to the customer, the radio system can be upgraded with latest features over the vehicle’s extensive lifetime.

In consumer radios, the SDR technology offers the possibility to implement multiple radio standards on the same hardware. This allows for a low-cost hardware production on a mass scale, even if the devices need to support different radio standards in different markets. Likewise, the addition of DRM functionality to existing hardware platforms has proven that the extra effort — and thus cost to support DRM on those products — is drastically reduced compared with new developments from scratch.

In the current world of mobile phones, analog FM reception is a feature in several markets. It grants users access to latest information without the need for expensive data plans or mobile network coverage typically only found in big cities.

AN APPLICATION

This is particularly true for emerging markets in Asia, Africa and South America, which are of high interest to the industry due to their growth potential. For those markets, the addition of DRM reception in the FM band can easily be designed into upcoming phones as no hardware changes are required. Even DRM networks for large-area coverage in the AM bands are supported through USB plugins.

A screenshot of the Fraunhofer MultimediaPlayer radio app under Android, combining baseband decoding for DRM (AM and VHF bands), DAB(+), and analog AM and FM with a full-featured service layer decoder. 

Thanks to DRM’s SDR approach, digital radio reception effectively becomes an application — but one that is independent of IP traffic and mobile network infrastructure. This presents a major USP to mobile phone manufacturers, for whom it has become increasingly difficult to compete on other relevant features due to the uniformly deployed Android platform.

In future, customers will quickly demand DRM digital radio support when selecting new phones the same way they demand analog FM support today. This is thanks to DRM’s free-to-air services with all their added-value features, such as Journaline advanced text services, EWF Emergency Warning Functionality, and increased diversity of program offerings at a significantly improved quality.

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Finally, professional equipment, such as monitoring receivers, measurement systems or head-ends for in-house radio distribution, benefit greatly from SDR implementations, as they can constantly be upgraded to follow the latest standard upgrades and continuous feature enhancements.

In summary, the SDR approach for digital radio reception helps bring down cost and at the same time speeds up the development of versatile and feature-rich radio receivers. Its benefits apply to all classes of receivers — from professional equipment to low-cost kitchen radios and mobile solutions. It enables manufacturers with flexibility and constantly growing maturity, which is hard to achieve with a traditional, hardware-centric radio architecture. The SDR approach is a key component for the availability of affordable and complete DRM radio sets and receiver solutions.

BY ALEXANDER ZINK AND MARTIN SPEITEL