CMX138 CML Microcircuits, CMX138 Datasheet - Page 53

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

Audio Scrambler and Sub-Audio Signalling Processor
Example: For 1010Hz, N = 43, R = 1. The programmed tones must only be set to frequencies from
288Hz to 3000Hz (R MUST NOT exceed 31 decimal).
9.2.3
Default values:
$C8 (P2.0)
Bits 11 (MSB) to 0 (LSB) set the transmitted CTCSS or DCS sub-audio signal level (pk-pk) with a
resolution of AV
$C8 (P2.1)
Bit 11, DCS 24: When this bit is set to ‘1’ 24 bit DCS codes are transmitted and decoded. When this bit is
cleared to '0' 23 bit codes are used.
The ‘detect threshold’ bits (bits 9 to 4) set the minimum CTCSS or DCS signal level that will be detected.
The levels are set according to the formula:
The CTCSS detected tone bandwidth is set in accordance with the following table:
© 2008 CML Microsystems Plc
Recommended for CTCSS ⇒
Recommended for use with
split tones and Tone Clone
P2.0
P2.1
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
Bit:
Bit:
Bit:
Program Block 2 – CTCSS and DCS Setup
15
15
1
0
15
N = Integer part of (0.042666 x frequency)
R = (0.042666 x frequency - N) x 6000 / frequency (round to nearest integer).
1
0
0
0
0
0
0
14
14
CTCSS and DCS TX LEVEL
1
CTCSS TONE BW AND LEVEL
1
14
DD
1
1
1
1
1
1
1
/16384 per LSB (0.201mV per LSB at AV
P2.0
P2.1
P2.2
Minimum Level = Detect Threshold × 2.2mV rms at AV
13
13
1
1
13
1
1
1
1
1
1
1
12
12
0
0
12
TM
0
0
0
0
0
0
0
$800
$008
$000
DCS
11
11
24
DCS
Sub-audio drop out time
11
24
Bit 3
0
0
1
1
1
1
User Defined CTCSS code N
10
10
0
10
0
Bit 2
9
9
CTCSS and DCS detect threshold
1
1
0
0
0
0
9
CTCSS and DCS detect threshold
Page 53
User Defined DCS Code bits 23/22 – 12
8
8
User Defined DCS Code bits 11 – 0
Bit 1
8
1
1
0
0
1
1
CTCSS and DCS Tx level
P2.3
P2.4
P2.5
P2.6
CTCSS and DCS Level
7
7
7
DD
Bit 0
=3.3V, giving a range 0 to 824.8mV pk-pk).
0
1
0
1
0
1
6
6
Reserved
6
$000
$000
$000
$000
5
5
5
Will Decode
User Defined CTCSS Code R
±0.8%
±1.3%
±1.6%
±1.8%
±0.5%
±1.1%
DD
4
4
4
= 3.3V
BANDWIDTH
0
3
3
3
CTCSS detect
CTCSS detect
bandwidth
Will Not Decode
bandwidth
2
2
2
±1.8%
±2.1%
±2.4%
±2.7%
±2.9%
±3.2%
D/138_FI1.0/5
1
1
1
CMX138
0
0
0