Our Objectives

keeping track of recent developments in the high tech industry
contributing our knowledge to further developments
introducing students in practical courses to the basics of softwaredesign

The Hardware

We are using a DAB-PCI-card by Technotrend GmbH. The actual DAB receiver is a plugin module called DFIRE (Digital audio Broadcasting Fully Integrated Receiver Engine) by Bosch Multimedia Systems GmbH. The DAB-Module itself receives the HF-Signal on VHF und SHF Bands and decodes it down to the demultiplexed streams. An integrated MPEG1-Layer2 audio decoder allows the direct output of digital Audio, which simply has to be converted into analog signals by any usual I2S-compatible D/A converter.
The DAB card is designed as a PCI board with a PCI bridge capable of busmastering for sending the decoded DAB datastreams to the host computer. This streams are multiplexed again according to the RDI (Receiver Data Interface) standard.
To control the DAB module some more I/O lines of the PCI bridge are used. For example it is possible to read and write status information, tune to another frequency or select the desired datastreams for the RD-Interface.

Fig 2: DFIRE-Module

Fig 1: DAB-PCI Card

Our latest development is a DAB-USB-Interface which can be attached to any computer with a USB port.

Technical data of the DAB-USB-Interface:

Operating System: Linux, Windows 98 or Windows 2000 (Mac OS support coming soon)
Port: USB (Universal Serial Bus) for RDI und decoded Audio (I2S)
Receiver: Bosch DFIRE-1, (DFIRE-2 from 02/2000)
Analog audio outputs: 1 fixed volume (line output), 1 variable volume (headphones output)

Fig 3: DAB-USB Kit

The Device Driver

The Device driver is currently designed for the operating system Linux. We decided to use Linux because of its open standards and its stability. The device driver is able to work with any number of DAB-PCI cards at one time. Its task is to abstract the functions of the hardware by providing a standardized interface to the user.
So a userlevel application is able to

control the on board hardware (PCI-bridge, DAC, GPIO)
control the communication between the DAB module and any application (reading status- and writing control-information)
capture and buffer the RDI stream for asynchronous processing by the application.

Fig 3: DAB-Driver Structure

DAB-Applications

The DAB server's communication protocol is based on HTTP and supports these features:

Web-based and authenticated configuration of server parameters, like tuned frequency etc.
User accessible statistic page of tuned ensemble.
Simple HTTP-based API to retrieve FIGs,
Streamserver support for MPEG- and Packet-data-streams.
Playlist support for all common MPEG players like winamp, xmms etc.

The Data-Decoder is a client-application that supports these features:

Decodes all known packet types of PAD and NPAD streams (MOT, Dynamic label, XPAD)
All decoded data can be displayed using any web browser.
All dataservices of an ensemble are decoded simultaneously.
Dynamic labels are kept in a history list.

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