RALCWI Vocoder
CMX608/CMX618/CMX638
2050bps
A 20ms Vocoder frame consists of 41 bits. 25 bits are more sensitive and 16 bits are less sensitive. A
single frame is transferred between the device and the host as 6 bytes. The table below shows the bit
positions in the transferred bytes. The more sensitive bits are shown white on black. The byte at the top is
the first out of the C-BUS for the encoder and the first into the C-BUS for the decoder.
7
6
5
4
3
2
1
0
B7
B6
B5
B4
B3
B2
B1
B9
B0
B8
B15
B23
B31
B39
x
B14
B22
B30
B38
x
B13
B21
B29
B37
x
B12
B20
B28
B36
x
B11
B19
B27
B35
x
B10
B18
B26
B34
x
B17
B25
B33
x
B16
B24
B32
B40
The seven most significant bits of the last byte are not used. Their values are indeterminate. For multiple
frame packets, each frame is 6 bytes (with 7 unused bits in the last byte) and is read or written to the C-
BUS in chronological order.
2400bps
A 20ms Vocoder frame consists of 48 bits. 24 bits are more sensitive and 24 bits are less sensitive. A
single frame is transferred between the device and the host as 6 bytes. The table below shows the bit
positions in the transferred bytes. The more sensitive bits are shown white on black. The byte at the top is
the first out of the C-BUS for the encoder and the first into the C-BUS for the decoder.
7
6
5
4
3
2
1
0
B7
B6
B5
B4
B3
B2
B1
B0
B15
B23
B31
B39
B47
B14
B22
B30
B38
B46
B13
B21
B29
B37
B45
B12
B20
B28
B36
B44
B11
B19
B27
B35
B43
B10
B18
B26
B34
B42
B9
B8
B17
B25
B33
B41
B16
B24
B32
B40
There are no un-used bits in the packet. For multiple frame packets, each frame is 6 bytes and is read or
written to the C-BUS in chronological order.
2012 CML Microsystems Plc
21
D/608_18_38/10
CMLMICRO [ CML MICROCIRCUITS ]
