DAB baseband decoder
Fraunhofer Institute for Integrated Circuits
DAB baseband decoder
The Idea
Modern radio receivers for car and home entertainment contain more and more software. This enables radio maker to support different radio standards on the same hardware platform.
Also updates or extensions become possible even in a very last stage of the development process and even in the field this remains feasible. With state of the art signal processors (DSPs) it is also possible to perform the baseband processing of the DAB signal on such a radio platform.
The Solution
The development of a DAB receiver software started with a reference model on a PC. Most of the DSPs, which are used in radio systems, are still fixed point DSPs. This requires the translation of the reference software into a fixed point library, which reduces the computational effort to a reasonable clock frequency of the DSP. This fixed point library is called Code Development Kit (CDK) and is based on pure C-code, which can be ported to an arbitrary processor.
The processor can be a standard high performance DSP like the C64 family from TI or Blackfin from Analog Devices or even an embedded core like ARM, MIPS, Tensilica. A third development step is then to optimize the C-code for a dedicated processor. This step makes use of the device-specific architecture like memory subsystem, special instruction and the optimal usage of internal pipeline structures. The complete DAB receiver including baseband processing, channel selection, audio and data decoding and several internal an external interfaces has to be tested.
For that purpose a test bed has been defined and installed in the lab. It consists of a signal source, which relies on a commercially available DAB signal generator, the DAB receiver itself including a frontend solution and a signal sink to record and post-process output data. The DAB receiver is controlled by a standard UART interface connected to a PC.
The Result
With this development program a fully validated DAB/DAB+/T-DMB solution is available for customers in the automotive and consumer market.
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