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Net-2000™ Voice Codec Unit
User’s Manual
Page 33
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
9600
0
0xbfc0
0x0000
0x0000
0x0000
0x72c0
0xc0c0
4
4850
4750
0xab16
0xe400
0x0000
0x0000
0x67c0
0xc0c0
6
9600
0
0x7fc0
0x0000
0x0000
0x0000
0x69c0
0xc0c0
21
3600
6000
0x5048
0x000e
0x4010
0x6a2e
0x65c0
0xc0c0
30
2400
7200
0x1030
0x000e
0x681a
0x511b
0x76c0
0xc0c0
29
9600
0
0x04c0
0x0986
0x0000
0x0000
0x0000
0xc1c0
53
3600
6000
0x0448
0x0986
0x000e
0x4010
0x6a2e
0xc1c0
62
9600
2400
7200
0x0430
0x0986
0x000e
0x681a
0x511b
0xc1c0
61
Table Key
AMBE-1000 Compatable Rates
AMBE-20xx Compatable Rates
AMBE+2 Compatable Rates
Channel Packet Bytes 18 and 19 (cmode)
The cmode element of the Channel packet contains the input flags to the decoder when it is
transmitted to the VCU and the output flags of the encoder when it is transmitted by the VCU. The
value of cmode also depends on the vocoder in use. Tables 12a and 12b list values for the decoder
input and encoder output flags of the Channel packet.
Cmode parameter
Decoder Input Flags
Byte 18
7 6 5 4 3 2 1 0
Byte 19
7 6 5 4 3 2 1 0
Hex Value
Nominal Value
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0x0000
Lost Frame
0 0 0 0 0 0 0 0
0 0 0 0 0 1 0 0
0x0004
Mute
0 0 0 0 0 0 0 0
0 0 0 0 1 0 0 0
0x0008
Tone Signaling
0 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0x4000
Table 18 a cmode Channel Parameter (Decoder Input Flags)
The nominal value for the cmode parameter should be zero when transmitting Channel packets to the
VCU. To get the decoder to perform a frame repeat set the Lost Frame flag. To generate comfort
noise (i.e., mute) set the Mute flag. The Tone Signaling Flag can be set to get the AMBE+2 vocoder
to ignore the channel data in the packet and generate a tone. The index and amplitude of the tone
should be set in the
tone[]
parameter of the Channel packet. The a-Law and U-Law decoders do
not support tone signaling and ignore this flag.
Cmode parameter
Encoder Output Flags
Byte 18
7 6 5 4 3 2 1 0
Byte 19
7 6 5 4 3 2 1 0
Hex Value
Voice Active
0 0 0 0 0 0 0 0
0 0 0 0 0 0 1 0
0x0002
VAD
0 0 0 0 0 1 0 0
0 0 0 0 0 0 0 0
0x0400
Tone Frame
1 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0x8000
Table 18 a cmode Channel Parameter (Decoder Input Flags)
When the VCU transmits Channel packets in response to Voice packets it sets the
cmode
parameter
with the flags returned by the encoder. The Voice Active flag is set when the packet must be