Digital Up Converter

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A digital up converter , or DUC for short , is an electronic circuit that converts a digital baseband signal into a higher-frequency signal in the intermediate frequency position (bandpass signal) or directly in the high-frequency position for emission. Practical applications can be found in the field of wireless digital message transmission, for example in base stations and mobile phones .

The functional counterpart to this is the digital down converter (DDC).

function

Block diagram with DUC

The digital baseband signal typically has a sampling rate equal to the symbol rate of the respective type of modulation. This digital baseband signal is usually channel-coded to protect against transmission errors and then converted in the DUC into a data stream with a higher sampling rate before it is mixed with the higher-frequency carrier signal in a mixer to an intermediate frequency position . The intermediate frequency is usually generated with a Direct Digital Synthesis (DDS). In a DUC, additional filters for pulse shaping, such as raised cosine filters, are integrated in order to ensure the highest possible spectral efficiency .

The digital data stream of the DUC thus formed and shaped in the intermediate frequency position is then fed to a digital-to-analog converter (DAC), which uses it to generate an analog bandpass signal. This is then converted into the actual frequency position for radiation with a further, analog mixer stage. In front of the antenna for radiation there are usually analog channel filters to minimize adjacent channel interference and a power amplifier (PA) to amplify the transmission signal to the desired transmission power.

The DUC can be implemented in a Field Programmable Gate Array (FPGA), digital signal processor (DSP), or in an application-specific integrated circuit (ASIC).

literature

  • John G. Proakis, Masoud Salehi: Communications Systems Engineering . 2nd Edition. Prentice Hall, 2002, ISBN 0-13-095007-6 .
  • Natasa Zivic: Modern Communications Technology. Walter De Gruyter GmbH, Berlin 2016, ISBN 978-3-11-041337-3 .
  • Tadeusz A. Wysocki, Bahram Honary, Beata J. Wysocki (Eds.): Signal Processing for Telecommunications and Multimedia. Springer Science + Business Media, New York 2005, ISBN 0-387-22928-0 .
  • Fa-Long Luo: Mobile Multimedia Broadcasting Standards. Technology and Practice, Springer Science + Business Media, New York 2009, ISBN 978-0-387-78262-1 .
  • Salah Bourennane (Ed.): Wireless Communication and Sensor Network. World Scientific Publishing Co. Pt. Ltd, London 2016, ISBN 978-981-3140-00-4 .

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