mirror of https://github.com/saitohirga/WSJT-X.git
121 lines
3.4 KiB
Fortran
121 lines
3.4 KiB
Fortran
program JTMSKfer
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! Measure the frame error rate (fer) of the rate 1/2, K=13 conv. code with
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! coherent BPSK, Viterbi decoding, perfect sync. The results are to be
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! compared with LDPC fer's produced by the routines in the ldpc sandbox folder.
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! These coherent BPSK results will not correspond to JTMSK.
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use iso_c_binding, only: c_loc,c_size_t
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use hashing
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use packjt
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character msg*22,decoded*22
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integer*4 i4tone(234) !Channel symbols (values 0-1)
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integer*1 e1(201)
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integer*4 r1(201)
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real rd(201), tmp
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integer*1, target :: d8(13)
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integer mettab(0:255,0:1) !Metric table for BPSK modulation
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integer*1 i1hash(4)
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integer*4 i4Msg6BitWords(12) !72-bit message as 6-bit words
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character*72 c72
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real xp(29)
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equivalence (ihash,i1hash)
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data xp/0.500000, 0.401241, 0.309897, 0.231832, 0.168095, &
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0.119704, 0.083523, 0.057387, 0.039215, 0.026890, &
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0.018084, 0.012184, 0.008196, 0.005475, 0.003808, &
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0.002481, 0.001710, 0.001052, 0.000789, 0.000469, &
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0.000329, 0.000225, 0.000187, 0.000086, 0.000063, &
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0.000017, 0.000091, 0.000032, 0.000045/
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nmsg=1
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! Get the metric table
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bias=0.0
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scale=20.0
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xln2=log(2.0)
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mettab=0
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do i=128,156
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x0=log(max(0.001,2.0*xp(i-127)))/xln2
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x1=log(max(0.001,2.0*(1-xp(i-127))))/xln2
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mettab(i,0)=nint(scale*(x0-bias))
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mettab(i,1)=nint(scale*(x1-bias))
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mettab(256-i,0)=mettab(i,1)
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mettab(256-i,1)=mettab(i,0)
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enddo
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do i=157,255
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mettab(i,0)=mettab(156,0)
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mettab(i,1)=mettab(156,1)
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mettab(256-i,0)=mettab(i,1)
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mettab(256-i,1)=mettab(i,0)
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enddo
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rdscale=2.0
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ntrials=1000000
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rate=72.0/198.0
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msg="123"
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call fmtmsg(msg,iz) !To upper case, collapse multiple blanks
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ichk=0
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call genmsk(msg,ichk,decoded,i4tone,itype) !Encode message into tone #s
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! Extract the data symbols, skipping over sync and parity bits
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n1=35
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n2=69
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n3=94
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r1(1:n1)=i4tone(11+1:11+n1)
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r1(n1+1:n1+n2)=i4tone(23+n1+1:23+n1+n2)
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r1(n1+n2+1:n1+n2+n3)=i4tone(35+n1+n2+1:35+n1+n2+n3)
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! call sgran()
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do idb=6,11
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db=idb/2.0-0.5 ! Eb/N0=1/(2*R*sigma^2), so sigma= sqrt( 1/(2*R*Eb/N0) )
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sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
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ngood=0 ! decoded = msg
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ngoodhash=0 ! will include undetected errors plus actual good ones
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do itrial=1,ntrials
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do i=1,n1+n2+n3
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tmp=( 2.0 * ( r1(i)-0.5 ) + sigma*gran() )*rdscale
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if( tmp .lt. 0 ) then
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rd(i)=min(127.0,-tmp)
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elseif( tmp .gt.0 ) then
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rd(i)=max(-tmp,-127.0)
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endif
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enddo
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j=0
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do i=1,99
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j=j+1
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e1(j)=rd(i)
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j=j+1
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e1(j)=rd(i+99)
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enddo
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nb1=87
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call vit213(e1,nb1,mettab,d8,metric)
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igoodhash=0
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ihash=nhash(c_loc(d8),int(9,c_size_t),146)
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ihash=2*iand(ihash,32767)
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decoded=" "
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if(d8(10).eq.i1hash(2) .and. d8(11).eq.i1hash(1)) then
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igoodhash=1
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write(c72,1012) d8(1:9)
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1012 format(9b8.8)
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read(c72,1014) i4Msg6BitWords
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1014 format(12b6.6)
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call unpackmsg(i4Msg6BitWords,decoded) !Unpack to get msgsent
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endif
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if( igoodhash .eq. 1) ngoodhash=ngoodhash+1
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if( decoded .eq. msg ) ngood=ngood+1
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enddo
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write(*,1023) db,sigma,ntrials,ngood,ngoodhash-ngood
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1023 format("db:",f6.2," sigma:",f6.2," ntot:",i8," good:",i8," undet:",i8)
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enddo
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end program JTMSKfer
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