Philips 22 DC 397 Service Manual page 32

PCS 88 643
EEPROM PARAMETER SETTINGS
Due to the absence of the RDS feature, parameters 10 to 33 of the 22DC397/75 have been deleted.
In addition to the hardware SDR, which is implemented in the IC96 14SV module, the set is equipped with a
software SDR control. Two new parameters were created for it, as described below.
[No [Function | Range__{Grid__| def. Value Eeprom Address
[60__| SDR time window 00H. 62H
SDR hysteresis 0..100% | O0H..OFH 05H
SDR decision levels FM
06H
number of decision levels
FFH
SDR Time Window
level-1
level 2 FFH
level 3 BFH
level 4 A6H
level 5 8DH
level 6 7AH
level 7.. 15 not used
SDR decision levels AM
08H
level 1 D5H 220H
level 2 CFH 221H
level 3 BDH 222H
level 4 ADH 223H
level 5 99H 224H
level 6 8DH 225H
level 7 70H 226H
level 8 1AH 227H
228H .. 22EH
level 9... 15 not used
This parameter describes the length of the time window, during that the fieldstrength is averaged. The time window
is set to n * 200ms where n is the programmed value. A value of OOhex will completely switch off SDR.
SDR Decision Levels FM and AM
These classes both consist of 16 bytes (32 in total). The first byte (byte 0) holds the number of decision levels. The
following 15 bytes (bytes 1 to 15) hold the decision levels themselves in descending order (from higher to lower
levels).
After calculating the averaged level, the value is compared to the array of decision levels. As soon as the averaged
value is lower than or equal to the next decision level in the array the treble cut is increased by 2dB. This means
that you have 6 decision levels for a maximum cut of 12dB in FM and 8 decision levels for a maximum cut of 16dB
in AM.
Note: Setting decision levels 1 and 2 to FFhex provides a static treble cut of 4 dB in FM.
SDR Hysteresis
This parameter helps to avoid nervous switching of the treble cut.
Example: Precondition is a level of A9hex and a treble cut of 6dB. Parameter 61 is OShex.
If the fourth decision level is A6hex and the signal drops below this, this will result in a treble cut of 8dB.
Now the signal level has at least to rise above A6hex + 5hex = ABhex to get back to a level cut of 6dB.
3 22 DC 397/75H