User`s manual
USB-3000™
User’s Manual Version 1.6a
Section 6 –Appendix
Page 56
DVSI Confidential Proprietary
Digital Voice Systems, Inc.
The Speech Compression Specialists
File Type. A hard-decision bit file contains compressed speech data output by the
can be used as input to the decoder. The data is packed using 8 bits per byte.
a, b, c, d, e f, g, h, i, j, k, l, m, n, o, p
red in a hard-decision bit file. Then the first two bytes of the file
gh and ijklmnop.
Soft-Decision Bit File Type compressed speech data output by the
n been converted to 4-bit soft-decision format. Soft-decision format is not output
der, but it can be input directly to the decoder when soft-decision decoding is
is packed using two soft-decision bits per byte. Each soft decision bit must be a 4-
bit value in the range from 0x0 to 0xF. A binary “0” is represented as 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6,
eing the most confident “0” and 0x7 being the least confident “0”. A binary “1” is
xF, 0xE, 0xD, 0xC, 0xB, 0xA, 0x9, or 0x8, with 0xF being the most confident “1” and
0x8 being the least confident “1”. If a soft-decision bit file is derived directly from a hard-decision bit file,
have maximum confidence and will be equal to either 0x0 for “0” or 0xF for “1”. If the
a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p
e first eight bytes of the
aaabbbb ccccdddd eeeeffff gggghhhh iiiijjjj kkkkllll mmmmnnnn
-bit soft-decision bits are denoted as A, B, C, D, E, F, G, H,
I, J, K, and L, then the first eight bytes of the file could be expressed as hex AB,
CD, EF, GH, IJ, KL, MN, and OP. A through P are each 4-bit soft-decision bits in
the range from 0x0 to 0xF. If the transmission is not ideal, then the values for each 4-
bit soft-decision bit will vary between 0x0 and 0xF depending upon the confidence of
each received bit.
6.3. Additional Reference Material
AMBE-3000™ vocoder chip Users Manual
http://www.dvsinc.com/literature.htm
2. Hard-Decision Bit
encoder. The bit file
For hard-decision, each bit must be 0 or 1. If the 16 bits
are the first 16 bits sto
will be binary abcdef
3. . A soft-decision bit file contains
encoder that has the
he encodirectly by t
specified. The data
or 0x7, with 0x0 b
represented as 0
then each bit will
16 bits
are the first 16 bits stored in a hard-decision bit file. Then th
converted soft-decision format file will be binary
a
oooopppp.
If each of the 16 4