The CMS0022 Cable (QAM) Demodulator is fully compliant with the European, US and Japanese downlink cable Standards DVB-C EN 300 429 and ITU J83 Annexes A/B/C (including DOCSIS 1.1/2.0). The core provides all the necessary functions between modulated QAM input to transport stream output.
J.83B designs can operate either from internal memory (short interleaving modes) or from shared external memory (long interleaving modes) by means of a versatile access controller.
Typical applications of the CMS0022 include head-end video and broadband data transmissions systems (CMTS), cable modem test equipment and point-to-point (PTP) or point-to-multipoint microwave radio links.
A range of synthesis options allows the core to be tailored for any particular application.
DVB-C/J83 demodulator
Overview
Key Features
- IF sub-sampling or I/Q baseband interface.
- Standard 188-byte MPEG Transport Stream output.
- 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.
- Full DVB-C/J83 QAM support: 16, 32, 64, 128, 256
- Number of synthesis options to optimise speed (& therefore symbol rate) vs. area.
- Implementation loss of <1dB for 128 or 256-QAM, and <0.5dB for other supported QAM modes.
- External RAM interface for long interleave modes.
- Number of debug signals available - carrier, timing lock, frequency offset etc.
- Supplied as a protected bitstream or netlist (megacore for Altera FPGA targets).