SI4706-D50 Datasheet, PDF (23/36 Pages) Silicon Laboratories – HIGH-PERFORMANCE FM AND RDS/RBDS RECEIVER

Si4706-D50
4.13. RDS Decoder
The Si4706 implements an advanced, patented, high-
performance RDS processor for demodulation, symbol
decoding, block synchronization, error detection, and
error correction. The RDS decoder provides several
significant benefits over traditional implementations,
including very fast and robust RDS synchronization in
noisy signal levels with very high block error rates
(BLER), industry-leading sensitivity, and improved data
reliability in all signal environments.
Figure 13 illustrates the benefit of robust
synchronization. The Si4706's strong synchronization
performance at noisy signal levels minimizes or even
eliminates re-synchronization time required as the
signal carrier-to-noise ratio (CNR) fluctuates. The
Si4706 decoder is continuously synchronized to the
RDS block/group despite loss of data due to data block
errors. This translates to lower loss of data compared to
competing solutions.
Figure 14 illustrates the Si4706 RDS decoder
performance. With the aid of robust synchronization, the
decoder additionally provides for operation at lower
sensitivity levels for a given BLER compared to
competing solutions, and delivers reception in
environments where signal power is very low or
compromised. The decoder failure probability drops
significantly when compared to competing solutions.
The Si4706 also provides unmatched flexibility in
programming the interaction between the host
processor and the device. The Si4706 can be
configured to provide varying levels of visibility from
very high visibility to each RDS block with
corresponding BLER, to a lower level of granularity
providing complete RDS groups with BLER by block.
Additionally, the Si4706 can provide interrupts on
changes to RDS block A and/or B. The Si4706 device
provides a configurable interrupt when RDS is
synchronized and RDS group data has been received.
The device provides configurable interrupts for up to
100 blocks with detailed BLER (25 groups), providing
flexibility in interrupt configuration to the host controller.
The Si4706 reports RDS decoder synchronization
status and detailed bit errors for each RDS block with
the FM_RDS_STATUS command. The range of
reportable bit errors that are detected and corrected are
0, 1-2, 3-5, and "not correctable." More than five bit
errors indicates that the corresponding block
information word is not correctable.
Re-synchronization time in
typical RDS decoder using
hard decision techniques.
Si4706 RDS advanced decoder
with persistent synchronization
delivers data during “dead time.”
CNR
Level at which typical RDS decoder returns
block error and declares sync loss.
time
Level at which Si4706 advanced
RDS decoder declares sync loss.
Figure 13. Illustrative Si4706 Advanced RDS Synchronization
Rev. 1.0
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