Dream DRM Receiver
Dream logo
Open-Source Software Implementation of a DRM Receiver
under the GNU General Public License (GPL)
Introduction - Source code - Auxiliaries - Software overview - Disclaimers - Forums

Introduction
DRM logo Digital Radio Mondiale (DRM) is a new digital radio standard for the long-, medium- and short-wave ranges. The standard was formed by a consortium in co-operation with the International Telecommunication Union (ITU). The new system offers the radio stations and new service providers access to the multimedia age with small bit rates for large target areas and long distances. For more information visit www.drm.org.

The bandwidth of a DRM bandpass signal is less than 20 kHz and the number of carriers used in the OFDM-modulation is relatively small (max. 460). These features motivate a real-time software implementation of a DRM-receiver on a conventional personal computer (PC) using the sound card as the input and output device. A long, medium and short wave front-end with an intermediate frequency (IF) between 5 kHz and 15 kHz is used to receive the DRM signal. Any commercial front-end with an IF of 455 kHz should be usable by adding a 455 kHz to 12 kHz adaptor (assumed the receiver bandwidth is sufficient for a DRM signal). Documentation of receiver modifications for DRM reception can be found at www.drmrx.org.

With this software project we intend to implement a working software receiver with, at least, the basic features. Since this project is created at a university and the fundamental idea of such an institution is to teach and stimulate the creativity, this source-code is free under the GNU-General Public License (GPL). Dream is a development project which uses the open source model to improve DRM technology. The main aim of this project is to implement and test new research results on an existing system, whereby the synchronization and channel estimation is of special interest.

The programming-language is C++. The code runs under Microsoft Windows and Linux. Start of the project was June 2001.

Although this software is going to be distributed as free software under the terms of the GPL this does not mean that its use is free of rights of others. The use may infringe third party IP and thus may not be legal in some countries.

The intended audience of the Dream software are people who are interested in how to decode a DRM stream and want to learn from the algorithms used in this software and people who want to help us improving the performance of the receiver and the source code.

If you just want to get the experience of DRM digital sound quality and expect a very stable and optimized receiver performance, we recommend to buy the commercial DRM Software Radio.

For the latest news click here.

Source Code
SourceForge Logo The source code is hosted at Sourceforge.net. Binary files of the software are not provided, since parts of the software may be subject to patent royalties in some countries. If you want to provide pre-compiled binaries based on this source, please consider this issue. We do not warrant for nor indemnify you in any way for patent infringement. You are solely responsible for your own actions. Please post your installation support questions in the public forum.

Auxiliaries

Software Overview
For a better clearness and an easier maintenance of the resulting code, an object oriented implementation was chosen [1] [11].

Modules

  • MSC: AAC+SBR decoding (including parametric stereo) [8], text message application, multimedia support for MOT Slideshow (DAB) application MOT Broadcast Web Site, Journaline® Service and EPG service.
  • SDC:Supported data entities:
    • Multiplex description data entity (type 0)
    • Label data entity (type 1)
    • Alternative frequency signalling (type 3)
    • Alternative frequency signalling: Schedule definition (type 4)
    • Application information data entity (type 5)
    • Alternative frequency signalling: Region definition (type 7)
    • Time and date information data entity (type 8)
    • Audio information data entity (type 9)
    • Alternative frequency signalling - other services (type 11)
    • Language and country data entity (type 12)
  • MLC (Multilevel coding):Iterative multi-stage decoding using Viterbi-algorithm [2].
  • Time synchronization:Acquisition: Guard-interval correlation followed by a moving average filter [3] [10], Tracking: Use estimated impulse response from channel estimation and do peak detection [9].
  • Frequency synchronization:Acquisition: FFT-based algorithm [4], Tracking: Using phase information of frequency pilots [5].
  • Channel estimation:One-dimensional Wiener filter in time direction [3] [6], Wiener filter in frequency direction (Optional: windowed DFT-based estimation [7] and linear interpolation).

References

[1] Fischer V.: Software Implementation of a Digital Radio Mondiale (DRM) Receiver, Part I (Framework), DRAFT, 2001.
[2] Proakis J. G.: Digital Communications, McGraw-Hill, 1995, pp. 441--507.
[3] Van Nee R. and Prasad R.: OFDM for wireless multimedia communications, Artech House, Boston, 2000
[4] Fischer V. and Kurpiers A.: Frequency Synchronization Strategy for a PC-based DRM Receiver, 7th International OFDM-Workshop (InOWo'02), Hamburg, 2002.
[5] Claßen F. and Meyr H.: Synchronization Algorithms for an OFDM System for Mobile Communication, 1. ITG Fachtagung Codierung für Quelle, Kanal und Übertragung, ITG Fachbericht 130, 1994, pp. 105--113.
[6] Hoeher P., Kaiser S. and Robertson P.: Two-dimensional pilot-symbol-aided channel estimation by Wiener filtering, IEEE Int. Conf. Acoustics, Speech and Signal Processing, Munich, Germany, Apr. 1997, pp. 1845-1848.
[7] Yang B. G., Letaief K. B., Cheng R. S. and Cao Z.: Windowed DFT based pilot-symbol-aided channel estimation for OFDM systems in multipath fading channels, IEEE International Conference on Vehicular Technology, VTC'00-Spring, Tokyo, Japan, May 2000, pp. 1480-1484.
[8] AudioCoding.com
[9] Yang B. G., Letaief K. B., Cheng R. S. and Cao Z.: Timing Recovery for OFDM Transmission, IEEE Journal on Selected Areas in Communications, Vol. 18, No. 11, November 2000
[10] Van de Beek, J. J., Sandell, M., Björjesson, P. O.: ML Estimation of Time and Frequency Offset in OFDM Systems, IEEE Transactions on Signal Processing, Vol. 45, No. 7, July 1997
[11] Kurpiers, A., Fischer V.: Open-Source Implementation of a Digital Radio Mondiale (DRM) Receiver, 9th International IEE Conference on HF Radio Systems and Techniques, Bath, United Kingdom, June 2003
[12] Speth, M., Fechtel, S. A., Fock, G., Meyr, H.: Optimum Receiver Design for Wireless Broad-Band Systems Using OFDM - Part I , IEEE Transactions on Communications, Vol. 47, No. 11, November 1999
[13] Speth, M., Fechtel, S. A., Fock, G., Meyr, H.: Optimum Receiver Design for OFDM-Based Broadband Transmission - Part II: A Case Study, IEEE Transactions on Communications, Vol. 49, No. 4, April 2001

Disclaimers
DRM LOGO: The DRM logo is a trade mark of Digital Radio Mondiale Association and is under license.

TRADEMARKS: The names of actual companies and products mentioned herein may be the trademarks of their respective owners.

LINKS TO THIRD PARTY SITES:This site contains links to other sites. We are not responsible for the content of any linked Web site.

Valid XHTML 1.0! Valid CSS!