CMX138 CML Microcircuits, CMX138 Datasheet - Page 58

• Manufacturer Part Number: CMX138
• Description: Audio Scrambler and Sub-Audio Signalling Processor
• Manufacturer: CML Microcircuits

Audio Scrambler and Sub-Audio Signalling Processor
The default settings are:
which will implement the line-up as shown in Figure 16 and Figure 17
$C8 (P4.10)
9.2.6
Removal of the Signal Processing block from reset (Power Down register $C0 b5 1→ 0), with the Protect
bit (Power Down register $C0 b4 = 0) kept low, will cause all of the Programming register words (P0 – P4)
to be reset to their default values.
© 2008 CML Microsystems Plc
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Pre-emphasis:
Compandor:
Scramble:
300Hz HPF:
Initialisation of the Programming Register Blocks:
Audio in
Discrim
Special Programming Register – do not change.
Voice LPF
01
00
10
11
Compress
(optional)
(pre-emphasis in position 1)
(Compandor in position 0)
(Scrambler in position 2)
(HPF in position 3)
Figure 17 Default Rx Audio Filter line-up
Figure 16 Default Tx Audio Filter line-up
300Hz Filter
Pre-emph
(optional)
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De-scrambler
(optional)
Scrambler
(optional)
300Hz Filter
De-emph
(optional)
Voice LPF &
Soft Limiter
Expander
(optional)
CTCSS
Audio
+
D/138_FI1.0/5
CMX138