Specifications
Net-2000™ VCU Users Manual
Version 4.0, December, 2013
Interface Protocol
6.3.3.8 Voice Data Packet Bytes 18 & 19 (cmode)
The cmode element of the packet contains the input flags to the encoder when it is received by a VCU and the
output flags of the decoder when it is transmitted from a VCU. The value of cmode also depends on the vocoder in
use. Table 34 and Table 35 list the input flags to the encoder and the output flags of the decoder for the cmode
ele
ment of Voice Data Packets.
cmode parameter
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Encoder Input Flags
Byte 18 Byte 19
Hex Value
AMBE_NS_ENABLE_FLAG 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0x0040
HPITCH_DET_ENABLE_FLAG
GMR-2+ Vocoder Only
0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0x0080
AMBE_FR_TONE_COMP_FLAG 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0x0200
AMBE_DTX_ENABLE_FLAG 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0x0800
AMBE_TONE_DET_ENABLE_FLAG 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0x1000
AMBE_AGC_ON_FLAG
APCO Enhanced Vocoder Only
0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0x2000
AMBE_DTMF_SEND_FLAG 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0x4000
Table 34 cmode Parameter (Used in the Encoder Command Packet)
Table 34 cmode Parameter (Used in the Encoder Command Packet) shows the flags used to set various features of
the encoder. For a description of what these flags see 4.9 Vocoder Options Configuration.
All the vocoders except the APCO Standard , when the AMBE_DTMF_SEND_FLAG is set to a 1 the encoder will
ignore the voice data in the packet and send a tone. The index and amplitude of the tone is set in the tone.idx and
tone.amp parameters of the Voice Data Packet ( see Table 24 tone.idx Parameter and Table 25 tone.idx Parameter
(co
nt’d)).
For the APCO Enhanced Vocoder if the AMBE_AGC_ON_FLAG is set, the automatic gain control is enabled and
attempts to raise or lower the incoming voice level to maintain a constant level.
The value of AMBE_TONE_DET_ENABLE_FLAG is always set ON for the AMBE® / AMBE+™ encoder.
cmode parameter
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Decoder 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_DATA_INVALID_FLAG 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0x0020
AMBE_DTMF_FRAME_FLAG 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0x8000
Table 35 cmode Parameter (Used in the Voice Response Packet)
All the vocoders except the APCO Standard decoder sets the AMBE_VOICE_ACTIVE_FLAG if the packet is not a
silence frame. The AMBE_DATA_INVALID_FLAG is set by the decoder if the data that was received in the
Channel Data Packet used to generate the Voice Data Packet was invalid, or if the Lost Frame or Mute flag was set
in the cmode element of the Channel Data Packet. All the vocoders except the APCO Standard decoder sets the
AMBE_DTMF_FRAME_FLAG if the packet contains a tone. The index and amplitude of the tone is set in the
tone.idx and tone.amp parameters of the Voice Data Packet ( see Table 24 tone.idx Parameter and Table 25 tone.idx
Param
eter (cont’d)).
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