MSP3421G MICRONAS [Micronas], MSP3421G Datasheet - Page 87

• Manufacturer Part Number: MSP3421G
• Description: Multistandard Sound Processor Family with Virtual Dolby Surround
• Manufacturer: MICRONAS [Micronas]

PRELIMINARY DATA SHEET
6.3. Manual/Compatibility Mode:
6.3.1. Automatic Switching between NICAM and
In case of bad NICAM reception or loss of the
NICAM-carrier, the MSP 34x1G offers an Automatic
Switching (fall back) to the analog sound (FM/AM-
mono), without the necessity for the controller of reading
and evaluating any parameters. If a proper NICAM sig-
nal returns, switching back to this source is performed
automatically as well. The feature evaluates the NICAM
ERROR_RATE and switches, if necessary, all output
channels which are assigned to the NICAM-source, to
the analog source, and vice versa.
An appropriate hysteresis algorithm avoids oscillating
effects (see Fig. 6–1). STATUS[9] and C_AD_BITS[11]
(Addr: 0023 hex) provide information about the actual
NICAM-FM/AM-status.
Selected Sound
NICAM
analog
sound
Fig. 6–1: Hysteresis for Automatic Switching
Table 6–5: Coding of Automatic NICAM/Analog Sound Switching;
Micronas
Mode
1
Default
2
3
1)
The NICAM path may be assigned to “Stereo or A/B”, “Stereo or A”, or “Stereo or B” source channels
(see Table 2–2 on page 12).
Description of Demodulator Write Registers
Analog Sound
Description
Automatic Switching with
internal threshold
Automatic Switching with
external threshold
(Customizing of Automatic
Sound Select)
Forced Analog Mono
Automatic Sound Select is on (MODUS[0] = 1)
threshold/2
threshold
ERROR_RATE
AUTO_FM [11:0]
Addr. = 00 21
bit[11:0] = 0
bit[11]
bit[10:1] = 25...1000
bit[0]
bit[11]
bit[10:1] = ignored
bit[0]
= 0
= threshold/2
= 1
= 1
= 1
hex
6.3.1.1. Function in Automatic Sound Select Mode
The Automatic Sound Select feature (MODUS[0]=1)
includes the procedure mentioned above. By default, the
internal ERROR_RATE threshold is set to 700
– NICAM
– analog Sound
The ERROR_RATE value of 700 corresponds to a
BER of approximately 5.46*10
Individual configuration of the threshold can be done
using Table 6–5. However, the internal setting used by
the standard selection is recommended.
The optimum NICAM sound can be assigned to the
MSP output channels by selecting one of the “Stereo
or A/B”, “Stereo or A”, or “Stereo or B” source chan-
nels
6.3.1.2. Function in Manual Mode
If the manual mode (MODUS[0]=0) is required, the
activation and configuration of the Automatic Switching
feature has to be done as described in Table 6–6.
Note, that the channel matrix of the corresponding out-
put-channels
NICAM-mode and need not to be changed in the FM/
AM-fallback case.
Example:
Required threshold = 500: bits[10:1] = 00 1111 1010
700
ERROR_RATE-
Threshold/dec
set by customer;
recommended
range: 50...2000
analog Sound if ERROR_RATE
must
NICAM if ERROR_RATE
be
set
Source Select:
Input at NICAM Path
NICAM or FM/AM,
depending on
ERROR_RATE
always FM/AM
-3
/s.
MSP 34x1G
according
dec
to
700
700/2
. i.e.:
1)
the
87