Digital Voice Systems Net-2000-P25, Руководство пользователя

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Net-2000™ Voice Codec Unit
User’s Manual
Page 23
DVSI Confidential Proprietary
Section 4 – Net-2000™ VCU Interface Protocol
The voice data format to synthesize is as follows:
The voice data to be synthesized is 16 bit PCM
(format & 0x00ff) == 0x00
All other formats are invalid.
channel [192]
For simplicity, and since channel data packets are small compared to nominal Ethernet frames all
192 Channel Data bytes are ALWAYS transmitted regardless of the actual bit-rate of the vocoder.
Each byte of the channel [] array contains one channel data “bit”.
Channel [192]
Bytes
(msb-lsb)
Bit
7 6 5 4 3 2 1 0
Bit
7 6 5 4 3 2 1 0
Parameter Name
… … … …
26 - 27 X x x x x x x x x x x x x x x x channel [0-1]
28 – 29 X x x x x x x x x x x x x x x x channel [2-3]
30 – 31 X x x x x x x x x x x x x x x x channel [4-5]
… … … …
216-217 X x x x x x x x x x x x x x x x channel [191-192]
Table 18 channel parameters
If channel[] contains hard decision data (no soft decision error detection)
channel[i] == 0x01 is a one,
channel[i] == 0x00 is a zero
If 8 bit soft decision error detection is used then,
channel[i] == 0xff is the most confident one
channel[i] = 0x00 is the most confident zero
Other values for the number of soft-decision bits are coded in a similar manner. For transmitting
DTX frames a channel data packet must contain all ones in the channel[] array. To signal no data
and force a frame repeat the channel[] array data packet must contain all zeros.
Voice Packet
Voice packets contain the voice data for one frame of voice with the control flags and data needed to
run the encoder. They are also transmitted by the VCU in response to Channel packets when in File
Mode and contain the synthesized speech output by the decoder.
Voice Packet
Bytes
(msb-lsb)
Bit
7 6 5 4 3 2 1 0
Bit
7 6 5 4 3 2 1 0
Parameter Name
a d
0 – 1 0 0 0 0 0 0 0 0 1 1 0 1 1 0 1 0 len