Specifications
Net-2000™ VCU Users Manual
Version 4.0, December, 2013
Interface Protocol
6.3.2.7 Channel Data Packet Bytes 6 to 17 (rate[0-5])
There are six rate information words and four parameter words that are common to the Encode Command Packet,
Decode Command Packet, Voice Response Packet and the Channel Response Packet. These are described below.
rate
[
6
]
vocode
r
rate and t
yp
e
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Bytes
B
y
te
(
n
)
B
y
te
(
n+1
)
Parameter Name
… … … …
6 - 7 x x x x x x x x x x x x x x x x rate [0]
8 - 9 x x x x x x x x x x x x x x x x rate [1]
10 - 11 x x x x x x x x x x x x x x x x rate [2]
12 - 13 x x x x x x x x x x x x x x x x rate [3]
14 - 15 x x x x x x x x x x x x x x x x rate [4]
16 - 17 x x x x x x x x 1 1 0 0 x x x x rate [5]
… … … …
Table 16 rate[0-5] Parameter
The six Rate words contain information of the vocoder and data/FEC rate details. This information will vary for the
types of vocoders. Rate information can be decoded as follows:
the bottom 8 bits of rate[0] contains the number of speech data bits-per-frame, (1 frame=20 ms)
the bottom 8 bits of rate[5] contains the total number of bits per frame (speech data bits plus FEC data bits)
the top 8 bits of rate[5] specifies the vocoder type:
NOTE: the mu-law and A-law coder use each byte in the channel data packet for a mu-law or A-law sample. The
soft-decision bits value in the packet should always be set to 8 for the mu-law or A-law coder.
For the AMBE® / AMBE+™ vocoders
the top 8 bits of rate[5] = 0xC0 , (<vocoder_type> = ambe2000)
For the AMBE+2™ vocoder
the top 8 bits of rate[5] = 0xC1 , (<vocoder_type> = ambe+2)
For the APCO Standard vocoder
the top 8 bits of rate[5] = 0xC2 , (<vocoder_type> = apco)
For the APCO Enhanced vocoder
the top 8 bits of rate[5] = 0xC3 , (<vocoder_type> = ambe+2a)
For the BGAN vocoder
the top 8 bits of rate[5] = 0xC8 , (<vocoder_type> = ambe+2i)
For the GMR-2+ vocoder
the top 8 bits of rate[5] = 0xC8 , (<vocoder_type> = ambe+2g)
For the GMR-1 vocoder
the top 8 bits of rate[5] = 0xC8 , (<vocoder_type> = ambe+2t)
(Subject to Change) Page 41
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