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| Introduction Digital Radio Mondiale ( DRM ) is a digital radio system for short-wave, AM/medium-wave and long-wave. It has been endorsed by the ITU, IEC and ETSI. DRM currently covers the broadcasting bands below 30 MHz. The quality of DRM audio is excellent, and the improvement upon analogue AM is immediately noticeable. Besides providing near-FM quality audio, the DRM system has the capacity to integrate data and text. The DRM signal is designed to fit in with the existing AM broadcast band plan, based on signals of 9 kHz or 10kHz bandwidth. The DRM system uses a type of transmission called COFDM (Coded Orthogonal Frequency Division Multiplex). This means that all the data, produced from the digitally encoded audio and associated data signals, is shared out for transmission across a large number of closely spaced carriers. All of these carriers are contained within the allotted transmission channel. The DRM system is designed so that the number of carriers can be varied, depending on factors such as the allotted channel bandwidth and degree of robustness required. The DRM system can use three different types of audio coding, depending on broadcasters’ preferences. MPEG4 AAC audio coding, augmented by SBR bandwidth extension, is used as a general-purpose audio coder and provides the highest quality. MPEG4 CELP speech coding is used for high quality speech coding where there is no musical content. HVXC speech coding can be used to provide a very low bit-rate speech coder. The robustness of the DRM signal can be chosen to match different propagation conditions. All you need to receive DRM transmissions is a PC with a sound card and a modified analog short-wave (MW, LW) receiver. The DX-394 has a 455kHz IF and with a downmixer it produces the 12kHz DRM signal that is fed to the microphone input on your computers sound card. Finally, you will need some software to decode the DRM signal and the good news is ... it's FREE!! Sourceforge.net Download qt-mt230nc.dll Monitor Internet DRM Board features:
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 DRM 12kHz Data Output Modified Hi-Z Antenna Socket |
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 455kHz IF Amplifier, Ceramic Filter and DRM Module |
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| DRM
Circuit Diagram |
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