Wavecom W-BitView V2.5.00 - Manual (Page 67)

BitView Manual V2.5.00 WAVECOM W-BV Custom Library
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Function:
De-interleaves a descrambled STANAG-4285 bit stream.
The setting of Deinterleaver Mode depends on the data rate and interleaver delay of the received
STANAG-4285 bit stream.
Interleaver delay [s] Data rate [bps]
Long (10.24) 2400
1200
75 - 600
Short (0.853) 2400
1200
75 - 600
STANAG-4285 Descrambler
In: Formatted STANAG-4285 data frame containing 8PSK symbols (3 bits/symbol)
Out: Descrambled STANAG-4285 bit stream
Function:
Descrambles a STANAG-4285 8PSK data frame encoded in big endian format. The frame must contain 176
3-bit symbols. This function does not contain any user settings.
Stream setup for Viterbi
In: Descrambled and de-interleaved STANAG-4285 bit stream
Out: Modified STANAG-4285 bit stream ready for Viterbi soft decision decoding
Function:
Modifies a descrambled and de-interleaved STANAG bit stream according to user data rate and readies it
for soft decision Viterbi decoding. Processing involves inserting three probability bits for soft decision
decoding, removing superfluous dibits for user data rates lower than 1200 bps and inserting erasures in
case of punctured codes.
Use User data rate to select the appropriate user data rate.
The table below lists the action taken by this function for each user data rate:
User data rate [bps] Action
2400 Depuncture for Rate = 2/3, i.e., insert an
erasure (‘0’) after 3 bits