Digital Set-top Box Solutions Satellite CX24123 Demodulator and FEC Decoder Low-power QPSK demodulator for worldwide satellite set-top box applications Conexant’s broadband communications portfolio includes a comprehensive suite of semiconductor solutions that enable the digital home and information network. The CX24123 is a DVB, DSS, and DCII compliant demodulator and Forward Error Correction (FEC) decoder. When combined with a satellite tuner, such as the CX24109 tuner, the CX24123 provides a complete broadband satellite front-end solution capable of operating from 1 to 45 Msps. The CX24123 is the ideal solution for a wide variety of applications in digital satellite set-top box, personal computer receivers and residential gateways. This DiSEqC™ 2.x compliant demodulator enables two-way communication between the set-top box and peripheral satellite equipment such as LowNoise Block Converters (LNB) and switches. CX24123 Distinguishing Features Providing digital derotation, digital filtering, equalization, and Viterbi/Reed- • DVB/DSS/DCII - compliant Solomon FEC, the CX24123 provides many advanced features that enhance • Symbol rates: 1 to 45 Msps overall system performance. The CX24123 automatically corrects for external quadrature gain/phase imbalances and for DC offsets. Input signal level • Automatic acquisition variations (e.g., due to rain fade) are compensated by automatic gain control • Low-power design (AGC). Frequency offsets due to inexpensive consumer LNBs are corrected • Internal SNR and BER monitors by a robust Carrier-Tracking Loop. • DiSEqC Level 2.x compatible A unique feature of the CX24123 is an automatic acquisition algorithm that • Low-Noise Block Converter (LNB) control searches and acquires the carrier within a ± 10 MHz range during initial acquisition and performs a smart search to reacquire the carrier during fade ™ • Available in both 80 and 64 pin TQFP conditions. The CX24123 has integrated signal-to-noise Ratio (SNR) and Bit Error Rate (BER) monitors for basic channel performance measurements, which saves time and test equipment during production. Part Number CX24123 Description Demodulator and FEC Decoder Digital Set-top Box Solutions Satellite CX24123 Features • DVB/DSS/DCII-compliant • External symbol clock reference • Symbol rates 1 to 45 Msps • Internal SNR and BER monitors • Internal PLL, only a single low-frequency crystal or clock is required • DiSEqC™ level 2.x two-way Low-Noise Block Converter (LNB) control • Automatic acquisition • Power-down mode • ±10 MHz acquisition range • Quadrature equalization compensation • Carrier tracking: ±5 MHz – ±3.0 dB gain imbalance • 6-bit Analog-to-Digital Converters (ADCs) – ±13-degree phase offset • 4-bit soft decision • Digital matched filtering CX24123 Applications • Multirate decimation filter • DVB/DSS/DCII set-top box and PC receivers • Internal carrier and bit-timing recovery • Residential gateways • Boundary scan test function Q Dual A/D VDATA QPSK/BPSK Viterbi Demodulator Q soft Decoder VDATA_CLK Tuner Interface Microprocessor Interface Auto Acquisition CX24123 Block Diagram © 2003, Conexant Systems, Inc. All Rights Reserved. Conexant and the Conexant logo are trademarks of Conexant Systems, Inc. All other trademarks are owned by their respective owners. Although Conexant strives for accuracy in all its publications, this material may contain errors or omissions and is subject to change without notice. THIS MATERIAL IS PROVIDED AS IS AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. 03-0746 www.conexant.com General Information: U.S. and Canada: (800) 854-8099 International: (949) 483-6996 Headquarters – Newport Beach 4311 Jamboree Rd, P.O. Box C Newport Beach, CA 92660-3095 Conexant shall not be liable for any special, indirect, incidental or consequential damages as a result of its use. Order# 102134A ReedSolomon Descrambler I soft I Deinterleaver • Serial or parallel output data interface RS_DATA[7:0] RS_CLOCK