SAA7806H NXP [NXP Semiconductors], SAA7806H Datasheet - Page 26

• Manufacturer Part Number: SAA7806H
• Description: One chip automotive CD audio device
• Manufacturer: NXP [NXP Semiconductors]

Philips Semiconductors
9397 750 13697
Objective data sheet
Fig 16. Bit detection
conditioning
6.6.5.2 Bit detector
signal
from
The bit detector block contains the slice level circuitry, a noise filter to limit HF-EFM signal
noise contribution, an equalizer, a zero-transition detector, a run length pushback circuit, a
digital PLL and jitter measurement logic.
All processing is done using the bit clock, and bandwidths are proportional to the channel
bit rate. To achieve this, RF data is resampled in the system clock domain to the bit clock
domain by using a sample-rate convertor. Blocks can be configured under microcontroller
control and are described in detail in the next paragraphs.
Noise filter:
the bandwidth of the incoming signal to
Slice level determination:
incoming signal asymmetry component. Bandwidth of the slice level determination circuit
is programmable via register SlicerBandwidth. Also the higher bandwidths for use after a
defect (see
proportional to the channel bit clock frequency. The slice level, or asymmetry, can be read
back via register SlicerAssym.
Equalizer:
frequency content of the incoming signal.
A five-tap presentable, asymmetrical equalizer is built in. The equalizer block diagram is
given in
Passband: 0f
Stopband: 0.28f
Rejection: 28 dB.
SRC
Figure
DETERMINE
In the bit detection circuit, a programmable equalizer is used, it boosts the high
Section “Defect
LEVEL
SLICE
The digital noise filter runs on the channel bit clock frequency f
FILTER
NOISE
b
17.
to 0.22f
b
to (f
clocked on PLL clock
Rev. 01 — 20 June 2005
b
b
DIGITAL
EQUALIZER
PLL
DIGITAL
0.28f
The slice level determination circuit compensates the
Detector”) are programmed in this register. The bandwidth is
b
)
MEASUREMENT
1
4
JITTER
TRANSITION
of the channel bit clock frequency:
PUSHBACK
RMS
DETECT
ZERO
RL2
One chip automotive CD audio device
PLL frequency
jitter value
slice level
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
to
demodulator
multiplex
001aab760
40
SAA7806
MEAS
b
. It will limit
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