SAA7706H/N107 NXP Semiconductors, SAA7706H/N107 Datasheet - Page 20

• Manufacturer Part Number: SAA7706H/N107
• Manufacturer: NXP Semiconductors

Specifications of SAA7706H/N107

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

Philips Semiconductors
8.4.1
The high-pass 1 (HP1 or narrow band noise level filter)
output of the second MPX decimation filter in a band from
60 kHz to 120 kHz is detected with an envelope detector
and decimated to a frequency of 38 kHz. The response
time of the detector is 100 s. Another option is the
high-pass 2 (HP2 or wide band noise level filter). This
output of the first MPX decimation filter is in a band from
60 to 240 kHz. It has the same properties and is also
decimated to the same 38 kHz. Which of the signals is
used (HP1 or HP2) is determined by the I
bit sel_nsdec.
8.4.2
The DCS block uses a sample rate converter to derive
from the XTAL clock, via a PLL, a 512 multiple of 19 kHz
(9.728 MHz). In the event of mono reception the DCS
circuit generates a preset frequency of n
In the event of stereo reception the frequency is exactly
n
the pilot and the stereo indication is done in the DSP
program.
2001 Mar 05
handbook, full pagewidth
Car radio Digital Signal Processor (DSP)
(1) Noise with wide band digital filter.
(2) Noise with small band digital filter.
19 kHz (DCS locked to N
(dB)
100
120
140
N
M
20
40
60
80
0
OISE LEVEL
ONO OR STEREO SWITCHING
0
(1)
50
Fig.12 Frequency response of noise level before decimation.
(2)
pilot tone). The detection of
2
100
C-bus
19 kHz 2 Hz.
150
20
The resulting noise information is rectified and has a word
length of 10 bits. This means that the lowest and/or the
highest possible level is not used. The noise level can be
detected and filtered in the DSP1-core and be used to
optimize the FM weak signal processing. The transfer
curves of both filters before decimation are shown in
Fig.12.
8.4.3
The VCO of the DCS block will be at 19 kHz 2 Hz exact
based in the event of no-pilot FM_MPX reception or in the
event of only RDS reception. In the event of stereo
reception the phase error is zero for a pilot tone with a
frequency of exactly 19 kHz.
T
HE AUTOMATIC LOCK SYSTEM
200
250
f (kHz)
Product specification
SAA7706H
MGT468
300