Digital Set-top Box Solutions
Satellite
CX24123 Demodulator and FEC Decoder
Low-power QPSK demodulator for worldwide satellite
set-top box applications
Conexant鈥檚 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
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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 卤 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.
CX24123 Distinguishing Features
鈥?DVB/DSS/DCII - compliant
鈥?Symbol rates: 1 to 45 Msps
鈥?Automatic acquisition
鈥?Low-power design
鈥?Internal SNR and BER monitors
鈥?DiSEqC Level 2.x compatible
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鈥?Low-Noise Block Converter
(LNB) control
鈥?Available in both 80 and 64 pin TQFP
Part Number
CX24123
Description
Demodulator and FEC Decoder
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