Digital Set-top Box Solutions
Satellite
CX24123 Distinguishing Features
DVB/DSS/DCII - compliant
Symbol rates: 1 to 45 Msps
Automatic acquisition
Low-power design
Internal SNR and BER monitors
DiSEqC
TM
Level 2.x compatible
Low-Noise Block Converter
(LNB) control
Available in both 80 and 64 pin TQFP
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
TM
2.x compliant demodulator enables two-way communication
between the set-top box and peripheral satellite equipment such as Low-
Noise Block Converters (LNB) and switches.
Providing digital derotation, digital filtering, equalization, and Viterbi/Reed-
Solomon FEC, the CX24123 provides many advanced features that enhance
overall system performance. The CX24123 automatically corrects for external
quadrature gain/phase imbalances and for DC offsets. Input signal level
variations (e.g., due to rain fade) are compensated by automatic gain control
(AGC). Frequency offsets due to inexpensive consumer LNBs are corrected
by a robust Carrier-Tracking Loop.
A unique feature of the CX24123 is an automatic acquisition algorithm that
searches and acquires the carrier within a 10 MHz range during initial
acquisition and performs a smart search to reacquire the carrier during fade
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
CX24123 Demodulator and FEC Decoder
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.
Conexant shall not be liable for any
special, indirect, incidental or consequential damages as a result of its use.
03-0746
Digital Set-top Box Solutions
Satellite
CX24123 Features
DVB/DSS/DCII-compliant
Symbol rates 1 to 45 Msps
Internal PLL, only a single low-frequency
crystal or clock is required
Automatic acquisition
10 MHz acquisition range
Carrier tracking: 5 MHz
6-bit Analog-to-Digital Converters (ADCs)
4-bit soft decision
Digital matched filtering
Multirate decimation filter
Internal carrier and bit-timing recovery
Boundary scan test function
Serial or parallel output data interface
External symbol clock reference
Internal SNR and BER monitors
DiSEqC
TM
level 2.x two-way Low-Noise Block Converter
(LNB) control
Power-down mode
Quadrature equalization compensation
3.0 dB gain imbalance
13-degree phase offset
CX24123 Applications
DVB/DSS/DCII set-top box and PC receivers
Residential gateways
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
Order# 102134A
VDATA_CLK
Microprocessor
Interface
Tuner
Interface
Auto
Acquisition
I soft
Q soft
VDATA
Reed-
Solomon
Deinterleaver
Descrambler
Viterbi
Decoder
RS_DATA[7:0]
RS_CLOCK
Dual
A/D
I
Q
QPSK/BPSK
Demodulator
CX24123 Block Diagram
PDF 
ZIP