RALCWI Vocoder
CMX608/CMX618/CMX638
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.
2750bps
A 20ms Vocoder frame consists of 55 bits. 23 bits are more sensitive and 32 bits are less sensitive. A
single frame is transferred between the device and the host as 7 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
x
B14
B22
B30
B38
B46
B54
B13
B21
B29
B37
B45
B53
B12
B20
B28
B36
B44
B52
B11
B19
B27
B35
B43
B51
B10
B18
B26
B34
B42
B50
B9
B8
B17
B25
B33
B41
B49
B16
B24
B32
B40
B48
The most significant bit of the last byte is un-used. Its value is indeterminate. For multiple frame packets,
each frame is 7 bytes (with 1 unused bit in the last byte) and is read or written to the C-BUS in
chronological order.
2014 CML Microsystems Plc
21
D/608_18_38/11
CMLMICRO [ CML MICROCIRCUITS ]
