FRS Signalling Processor
CMX882
Tone cloning should not be used in systems where tones 41 to 51 or other split tones (tones between the
frequencies of tones 1 to 40) may be received. The all call tone 40 can still be used after tone cloning
has been performed.
CTCSS Tones
Table 3 lists the CTCSS tones available. The tone numbers are decimal equivalents of the numbers
written to the Audio & Device Address Control register ($C2) and reported in the Tone Status register
($CC).
Table 3 CTCSS Tones
Tone
Number
001
01
Freq.
(Hz)
Tone
Number
20
Freq.
(Hz)
Tone
Number
402
41
Freq.
(Hz)
No Tone
67.0
131.8
136.5
141.3
146.2
151.4
156.7
162.2
167.9
173.8
179.9
186.2
192.8
203.5
210.7
218.1
225.7
233.6
241.8
250.3
69.3
62.5*
21
159.8*
165.5*
171.3*
177.3*
183.5*
189.9*
196.6*
199.5*
206.5*
229.1*
254.1*
Reserved
Invalid
tone
02
71.9
22
42
03
74.4
23
43
04
77.0
24
44
05
79.7
25
45
06
82.5
26
46
07
85.4
27
47
08
88.5
28
48
09
91.5
29
49
10
94.8
30
50
11
97.4
31
51
12
100.0
103.5
107.2
110.9
114.8
118.8
123.0
127.3
32
52-54
13
33
553
14
34
15
35
>=56
Reserved
16
36
17
37
18
38
19
39
* Subaudio tone not in TIA-603A standard.
Notes:
1
Tone number 00 in the Tone Status register ($CC) indicates that none of the above subaudio
tones is being detected - see also section 1.6.19. If tone number 00 is programmed into the
Audio & Device Address Control register ($C2) only tone 40 will be scanned for - see note 2. If
CTCSS transmit is selected this tone setting will cause the CTCSS generator to output no
signal.
2
3
Tone number 40 provides an all user CTCSS tone option; regardless of the subaudio tones set,
the CMX882 will indicate to the host when this tone is detected whenever the CTCSS detector is
enabled. This feature is useful for implementing emergency type calls e.g. all call.
Tone number 55 is reported in the Tone Status register ($CC), when CTCSS receive is enabled
and a subaudio tone is detected that does not correspond to the selected tone or the all-call tone
(tone number 40). This could be a tone in the subaudio band which is not in the table or a tone
in the table which is not the selected tone or all-call tone.
2004 CML Microsystems Plc
20
D/882/7
CMLMICRO [ CML MICROCIRCUITS ]
