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Refine a test program and add comments.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8203 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
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Steven Franke 2017-10-31 19:51:21 +00:00
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commit a45f1f079c
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lib/fsk4hf/jt65osdtest.f90
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@ -1,32 +1,59 @@
program jt65osdtest
!
! Test k9an's JT65 encoder by comparing codewords with
! Demonstrate some procedures that can be used to implement an ordered-
! statistics decoder for JT65.
! 1. Test JT65 generator-matrix-based encoding by comparing codewords with
! those produced by the tried-and-true KA9Q encoder
! 2. Demonstrate how to reconfigure the generator matrix to make an arbitrary
! subset of 12 symbols the systematic symbols, and show that re-encoding using
! the subset of symbols regenerates the original codeword.
!
use jt65_generator_matrix
use gf64math
use packjt
character*22 message
integer m(12),cwka9q(63),cwk9an(63),cwtest(63)
integer gmrb(12,63)
do i=1,12
m(i)=i
enddo
data m/61,51,10,42,51,55, 3,29,53,55,58,42/ !"K9AN K1JT -25"
message="K9AN K1JT RRR"
call packmsg(message,m,itype,.false.)
write(*,*) 'Message text: ',message
write(*,*) 'Message symbols:'
write(*,'(12i3)') m
! Encode using Karn encoder.
call rs_encode(m,cwka9q)
write(*,*) 'KA9Q codeword'
write(*,'(63i3)') cwka9q
! Encode using generator matrix.
call gf64_encode(g,m,cwk9an)
write(*,*) 'K9AN codeword'
write(*,'(63i3)') cwk9an
! The message symbols are the last 12 symbols of the codeword. For this test,
! "pretend" that the symbols at positions 1,3,5,7,9,11,13,15,17,19,21,23 are
! the best received symbols, i.e. the best symbols are all parity symbols.
! Reorder columns of the generator matrix so that the best symbols are in front
! and then use Gauss-Jordan elimination to create a generator matrix that
! can be used to re-encode the best 12 symbols, producing the same codeword
! that we started with.
gmrb=g
call gf64_standardize_genmat(gmrb)
do i=1,12
write(*,'(63i3)') gmrb(i,:)
gmrb(1:12,i)=g(1:12,2*i-1)
gmrb(1:12,i+12)=g(1:12,2*i)
enddo
m(1:12)=cwk9an(1:12)
call gf64_encode(gmrb,m,cwtest)
write(*,*) 'Test message:'
call gf64_standardize_genmat(gmrb)
! Now demonstrate that we can use the revised generator matrix to encode the 12
! best symbols and recover the codeword that we started with.
m(1:12)=cwk9an(1:23:2) !Take symbols 1,3,5,...23 as the message
call gf64_encode(gmrb,m,cwtest) !reencode using the revised generator matrix
write(*,*) 'Re-encode using generator matrix reconfigured to use odd-index symbols starting at 1 as the message:'
write(*,'(12i3)') m
write(*,*) 'Codeword:'
write(*,'(63i3)') cwtest
write(*,*) 'Re-encoded codeword should be the same as the original codeword:'
write(*,'(63i3)') cwtest !This should be the same as the original cw.
end program jt65osdtest