cx25840 Conexant Systems, Inc., cx25840 Datasheet - Page 107

• Manufacturer Part Number: cx25840
• Description: Video Decoder And Broadcast Audio
• Manufacturer: Conexant Systems, Inc.

CX25840/1/2/3 Data Sheet
3.19
102284B
8/3/05
Audio Decoder Features
The CX25843 integrates all the demodulation and decoding functionality required for
converting the sound IF output of a television tuner to demodulated and decoded
baseband stereo audio. The device supports the major television broadcast audio
standards found throughout the world.
An embedded microcontroller handles the detection and configuration of the
broadcast demodulator and decoder so that minimal user intervention is required. The
microprocessor and associated firmware, which is downloaded by the system, will
perform the following functions:
The audio decoder integrates two independent stereo baseband audio processing
blocks that can perform the following functions:
BTSC (IF or AF input)
A2-BG/DK/M
EIA-J
AM-L
NICAM-BG/DK/I/L
High deviation or very high deviation FM
FM Radio (IF or AF input)
Automatic broadcast audio standard detection and configuration of the appropriate
registers with manual override of some registers available
Automatic detection of secondary audio broadcasts (SAP)
Automatic AM or FM detection with NICAM-L and NICAM-DK signals
Automatic fallback from and return to NICAM
Automatic fallback from FM stereo to mono or dual to mono
Automatic mute for low carrier strength
Volume
Balance
3-band equalization
Auto volume control to maintain an average sound level
Stereo with or without dBx companding
Mono
SAP
Stereo
Dual language
Mono
Stereo
Dual language
Mono
Mono
Stereo
Dual language including Tri-Vox
Mono
AM or FM analog fallback
Mono
Stereo
Mono
With or without RDS
Conexant
Detailed Functional Description
3-81