IP Catalog > DSP & Math IP > Modulation/Demodulation IP > Quadrature Amplitude Modulation IP > Multi-mode QAM Demodulator

Multi-mode QAM Demodulator

Overview

The CMS0006 Universal QAM Demodulator is a 4th generation design that exploits Commsonic’s experience of QAM and OFDM systems for broadband terrestrial, satellite and cable modems.

The demodulator core has been designed to lock robustly in the presence of noise, frequency & timing offsets, static & dynamic multi-path channels and various other forms of interference. The demodulator core consists of three major sub modules: the Radio interface & decimator, Symbol timing recovery and the Equaliser.

The operation of the demodulator is fully automated by an internal state machine.

Key Features

  • IF sub-sampling or I/Q baseband interface.
  • Variable ADC width support.
  • Single external clock source required.
  • Single external analogue loop for AGC.
  • Fully digital and automatic timing & frequency recovery - no VCXO or AFC required.
  • Fully-digital matched channel filter for robust performance in the presence of ACI.
  • Blind and decision-directed adaption algorithms ensure rapid convergence of AGC, PLL and equaliser sub-systems.
  • Automatic channel equalisation using LTE and DFE algorithms - signal quality estimate available.
  • Symbol rate recovery up to approximately 40% of the master clock frequency.
  • Large QAM support : BPSK, (O)QPSK, 8, 16, 32, 64, 128, 256.
  • Number of synthesis options to optimise speed (& therefore symbol rate) vs. area.
  • Software programmable symbol demapping.
  • Integrates with Commsonics CMS0004(QAM Modulator), CMS0003(FEC) and CMS0002(Viterbi) cores to form a complete broadband Modem.
  • Number of debug signals available - carrier, timing lock, frequency offset etc.

Block Diagram

Multi-mode QAM Demodulator Block Diagram

Technical Specifications

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