CYW4343X
Figure 42. Soft Muting Characteristic
Input C/N (dB)
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High Cut—A programmable high-cut filter is provided to reduce the amount of high-frequency noise caused by static in the
output audio signal. Like the soft mute circuit, it is fully programmable to provide any amount of high cut based on the FM
signal C/N.
Audio Pause Detect—The FM receiver monitors the magnitude of the audio signal and notifies the host through an inter-
rupt when the magnitude of the signal has fallen below the threshold set for a programmable period. This feature can be
used to provide alternate frequency jumps during periods of silence to minimize disturbances to the listener. Filtering tech-
niques are used within the audio pause detection block to provide more robust presence-to-silence detection and silence-
to-presence detection.
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Automatic Antenna Tuning—The CYW4343X has an on-chip automatic antenna tuning network. When used with a single
off-chip inductor, the on-chip circuitry automatically chooses an optimal on-chip matching component to obtain the highest
signal strength for the desired frequency. The high-Q nature of this matching network simultaneously provides out-of-band
blocking protection as well as a reduction of radiated spurious emissions from the FM antenna. It is designed to accommo-
date a wide range of external wire antennas.
11.10 RDS/RBDS
The CYW4343X integrates a RDS/RBDS modem, the decoder includes programmable filtering and buffering functions. The RDS/
RBDS data can be read out through the HCI interface.
In addition, the RDS/RBDS receive functionality supports the following:
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Block decoding, error correction, and synchronization
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A flywheel synchronization feature, allowing the host to set parameters for acquisition, maintenance, and loss of sync. (It is
possible to set up the CYW4343X such that synchronization is achieved when a minimum of two good blocks (error free)
are decoded in sequence. The number of good blocks required for sync is programmable.)
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■
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■
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Storage capability up to 126 blocks of RDS data
Full or partial block-B match detection with host interruption
Audio pause detection with programmable parameters
Program Identification (PI) code detection with host interruption
Automatic frequency jumping
Block-E filtering
Soft muting
Document No. 002-14797 Rev. *H
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