Specifications

Net-2000™ VCU Users Manual
Version 4.0, December, 2013
Interface Protocol
t
one is set in the tone.idx and tone.amp parameters of the Channel Data Packet. The a-Law and U-Law decoders do
not support tone signaling and ignore the AMBE_DTMF_SEND_FLAG.
cmode parameter
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Encoder Output Flags
Byte 18 Byte 19
Hex Value
AMBE_VOICE_ACTIVE_FLAG 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0x0002
AMBE_VAD_FLAG 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0x0400
AMBE_DTMF_FRAME_FLAG 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0x8000
Table 23 cmode Parameter (Used in the Channel Response Packet)
When the VCU transmits Channel Data Packets it sets the cmode parameter with the flags returned by the encoder.
The AMBE_VOICE_ACTIVE_FLAG is set when the packet must be transmitted to the decoder (if cleared and
DTX is in use the frame does not need to be transmitted). If the AMBE_VAD_FLAG is set the packet contains
voice data (if cleared the frame is a silence frame). If the AMBE_DTMF_FRAME_FLAG flag is set the packet
contains tone data. The index and amplitude of the tone are reported in the tone.idx and tone.amp parameters of the
Channel Data Packet (see Table 24 tone.idx Parameter and Table 25 tone.idx Parameter (cont’d)).
The AMBE/AMBE+™ and AMBE+2™ coders both support the DTMF_FRAME_FLAG.
The AMBE+2™ coder supports the AMBE_VAD_FLAG.
The AMBE/AMBE+™ coder does not support the AMBE_VAD_FLAG flag and uses the
AMBE_VOICE_ACTIVE_FLAG flag for that function. The AMBE/AMBE+™ coder does not have a flag to
indicate whether the packet should be transmitted. With the AMBE/AMBE+™ coder you must transmit the first
silence frame following a frame with AMBE_VOICE_ACTIVE_FLAG set to do DTX.
The GMR-2+ and BGAN vocoders have the VAD set internally and it is always ON.
The mu-law and A-law coders don't support any of these Encoder Output Flags.
(Subject to Change) Page 45
DVSI CONFIDENTIAL PROPRIETARY