MSP3411G Micronas, MSP3411G Datasheet - Page 86

• Manufacturer Part Number: MSP3411G
• Description: (MSP34x1G) Multistandard Sound Processor Family
• Manufacturer: Micronas

MSP 34x1G
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 of the controller 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.
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
Table 6–5: Coding of Automatic NICAM/Analog Sound Switching; Reset Status: Mode 0
86
Mode
0
1
2
3
1)
In case of Automatic Sound Select (MODUS[0] = 1), bit [0] of AUTO_FM is ignored
In case of Automatic Sound Select (MODUS[0] = 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
Compatible to MSP 3410B, i.e.
automatic switching is disabled
Automatic Switching with
internal threshold
(Default, if Automatic Sound
Select is on)
Automatic Switching with
external threshold
(Customizing of Automatic
Sound Select)
Forced analog mono mode, i.e.
Automatic Switching is disabled
(Customizing of Automatic
Sound Select)
analog Sound if ERROR_RATE
NICAM if ERROR_RATE
-3
/s.
AUTO_FM [11:0]
Addr. = 00 21
Bit
Bits
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
dec
. i.e. :
700
700/2
[0]
[10:1] = 0
[11]
[0]
[10:1] = 0
[11]
[0]
[10:1] = 25..1000
[11]
[0]
[10:1] = 0
[11]
= 0
= 0
= 1
= 0
= 1
= threshold/2
= 0
= 1
= 1
hex
Individual configuration of the threshold can be done
using Table 6–5, whereby the bits 0 and 11 of
AUTO_FM are ignored. It is recommended to use the
internal setting used by the standard selection.
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 channels.
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 6–5.
Note, that the channel matrix of the corresponding out-
put
NICAM mode and need not to be changed in the
FM/AM-fallback case.
Example:
Required threshold = 500: bits [10:1]=00 1111 1010
Selected Sound
NICAM
analog
Sound
Fig. 6–1: Hysteresis for Automatic Switching
channels
ERROR_RATE-
Threshold/dec
none
700
set by customer;
recommended
range: 50...2000
none
threshold/2
must
PRELIMINARY DATA SHEET
be
MICRONAS INTERMETALL
threshold
Source Select:
Input at NICAM Path
always NICAM; Mute in
case of no NICAM available
NICAM or FM/AM,
depending on
ERROR_RATE
always FM/AM
set
according
ERROR_RATE
to
1)
the