Implementing next generation audio broadcast standards with Ensigma RPUs

In an article published a few months ago, I gave an overview of the new Ensigma Series5 RPUs and talked about the support we offer for customers targeting various global or regional video broadcast standards. In this blog post, I would like to describe how Ensigma RPUs also support for radio broadcast standards.

There are many flavors to audio broadcast

A number of audio broadcast standards exist in the market today. The table below gives a subset of the popular audio broadcast standards.

Audio broadcast standards - DAB FM and AM radio

Ensigma RPU support for audio broadcast standards

The proliferation of audio broadcast standards makes it highly desirable to have a single hardware platform that is flexible to support multiple flavors. The Ensigma RPU provides such a generic architecture that allows support for multiple standards. The figure below shows the layered architecture for a typical DAB/DAB+/DMB radio.


01-DAB DMB software architecture


The blocks implemented as part of the Ensigma RPU include

  • Physical Layer Demod
  • DMA controller (DMAC)
  • ECP Driver
  • PHY Driver
  • Physical Layer
  • PHY API Layer
  • Decoded Data Processing/FIC Handler Layer

DAB and HD Radio

In the following sections, I will discuss some implementation details to support DAB/DAB+ and HD Radio, but most of this functionality is equally applicable to other radio standards as well.

02-DAB software architecture

The DAB Ensemble Decode performs a number of functions such as

  • Signal conditioning of the incoming signal.
  • Autonomous acquisition and tracking of the DAB signal.
  • Control of RF tuner (via API defined RF control function interface).
  • Detection of Transmitter Identification (TII) codes from the appropriate received NULL symbols.
  • Estimation of the signal to noise ratio (SNR) of incoming signal.
  • Demodulation of Fast Information Channel (FIC) and Main Service Channel (MSC) symbols, time and frequency de-interleaving and the Viterbi decoding of the FIC and MSC sub-channels.
  • Enhanced stream mode error protection, including sync byte detection, convolutional de-interleaving and Reed-Solomon decoding.
  • Reed-Solomon decoding for enhanced packet mode error protection.
  • The demodulation capacity and the number of sub-channels that can be supported by the physical layer are configurable, allowing a trade-off between system capabilities and memory footprint to be defined by the stack

The Radio Protocol Stack performs functions such as

  • Band scanning to identify DAB/DMB signals.
  • Interpretation of Fast Information Channel
  • Configures of PHY to decode the required sub-channels
  • Indication of changes in service make-up at service reconfigurations.
  • Packet service component decoding including enhanced packet mode error protection

HD Radio was developed in partnership with DTS (Ibiquity) with the core stack and PHY developed by DTS on the Ensigma RPU. Imagination enhanced the architecture further to add a HD core and peripheral wrappers to support multiple HD channels.

Evaluation platform

The RPU comes with an evaluation platform that enables quick prototyping and testing with standard tuners. Codescape Tools provide consistent tool support across Imagination’s offering.

03-Ensigma bring-up board for DAB

To summarize, Ensigma RPUs are flexibly designed to address the needs of high-speed connectivity, TV demodulation and radio demodulation standards.

Interested in our unique Ensigma communications technology? Then subscribe to our blog and follow us on Twitter for more exciting news on Imagination’s Ensigma RPUs!

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