RALCWI Vocoder
CMX608/CMX618/CMX638
Format 2 This format corresponds with the row and column layout of a standard telephone keypad
matrix. This format is used when bit 7 of the VCFG register ($07) is set to '1'.
Row Index
Bit 3:2
1209Hz
1336Hz
1477Hz
1633Hz
697Hz
770Hz
852Hz
941Hz
1
4
7
*
2
5
8
0
3
6
9
#
A
B
C
D
0
1
2
3
Column Index
Bit 1:0
0
1
2
3
Table 3 Standard DTMF Keypad Layout
This results in the following table in ascending numerical order for the bit patterns.
Bit 3
0
Bit 2
0
Bit 1
0
Bit 0
0
Symbol
1
2
3
A
4
5
6
B
7
8
9
C
*
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
0
#
D
1
1
1
0
1
1
1
1
Table 4 DTMF - Format 2
5.8.
Operation with STD (Single Tones)
The CMX608, CMX618 and CMX638 (in half-duplex mode only) can be enabled to send or receive single
tones. This facility is not available when the CMX638 is used in full-duplex mode.
The STD generators and detectors are provided so that commonly encountered tones can be reproduced
naturally at the other end of a Vocoded link, rather than being interpreted as a form of speech. They should
not be relied upon to provide an error free method of relaying tone signalling to other decoders.
2012 CML Microsystems Plc
29
D/608_18_38/10
CMLMICRO [ CML MICROCIRCUITS ]
