FRS/PMR446/GMRS Family Radio Processor
21
CMX838 Advance Information
4.2.3 CTCSS Subaudio Decoder and Encoder Tone Set
The CMX838 supports all popular subaudio tones with a unique, full performance, 'one-of-any' rapid detect
capability that adds support for end product group calling and Tone Cloning™ features. The digital processor
essentially contains 51 decoders to analyze the receive signal. Each decoder can independently be enabled
or disabled via configuration tasks.
The result of the subaudio signal analysis is available in the subaudio status register ($94). Both a decode
status bit, and a decoder index number are reported in the status register. The decode status bit is a logic one
when an enabled decoder senses that the input signal matches its center frequency – the index number will
be that of the matching decoder. If the input signal does not contain a subaudio signal that matches an
enabled decoder’s center frequency then the status bit is a logic zero – in this case the decoder index number
is reported as:
A. 62 if there is a significant subaudio frequency present.
B. 63 if the no tone timer has expired indicating there is no significant subaudio frequency present now, or
C. 0 if no subaudio signal has been seen since the subaudio processor was enabled or most recently placed
in RX mode.
No. Frequency (Hz)
No. Frequency (Hz)
1.
67.0
27.
159.8*
2.
69.3
28.
162.2
3.
71.9
29.
165.5*
4.
74.4
30.
167.9
5.
77.0
31.
171.3*
6.
79.7
32.
173.8
7.
82.5
33.
177.3*
8.
85.4
34.
179.9
9.
88.5
35.
183.5*
10.
91.5
36.
186.2
11.
94.8
37.
189.9*
12.
97.4
38.
192.8
13.
100.0
39.
196.6*
14.
103.5
40.
199.5*
15.
107.2
41.
203.5
16.
110.9
42.
206.5*
17.
114.8
43.
210.7
18.
118.8
44.
218.1
19.
123.0
45.
225.7
20.
127.3
46.
229.1*
21.
131.8
47.
233.6
22.
136.5
48.
241.8
23.
141.3
49.
250.3
24.
146.2
50.
254.1*
25.
151.4
51. User Programmable
26.
156.7
* Subaudible Tones not included in TIA-603 standard
Table 2: CTCSS Subaudio Tone Frequencies with their Corresponding Index Number
¤2001 MX-COM, Inc.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480221.002
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