mirror of https://github.com/saitohirga/WSJT-X.git
88 lines
2.8 KiB
Fortran
88 lines
2.8 KiB
Fortran
subroutine genjt9(message,minutes,lwave,msgsent,d7,iwave,nwave)
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! Encodes a "JT9-minutes" message and returns array d7(81) of tone
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! values in the range 0-8. If lwave is true, also returns a generated
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! waveform in iwave(nwave), at 12000 samples per second.
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parameter (NMAX=1800*12000) !Max length of wave file
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character*22 message !Message to be generated
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character*22 msgsent !Message as it will be received
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character*3 cok
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real*8 dt,phi,f,f0,dfgen,dphi,twopi
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integer*2 iwave(NMAX) !Generated wave file
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integer d0(14) !72-bit message + 12-bit CRC, as 6-bit bytes
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integer*1 d1(84) !72+12 = 84 single bits
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integer d2(11) !72+12 bits, as 8-bit words
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integer*1 d3(11) !72+12 bits, as 8-bit bytes
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integer*1 d4(198) !Encoded information-carrying bits
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integer*1 d5(198) !Bits from d4, after interleaving
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integer*1 d6(66) !Symbols from d5, values 0-7
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integer*1 d7(66) !Gray-coded symbols, values 0-7
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integer*1 d8(81) !Channel symbols including sync, values 0-8
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logical lwave
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integer isync(15)
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data isync/1,6,11,16,21,26,31,39,45,51,57,63,69,75,81/
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data twopi/6.283185307179586476d0/
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save
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call chkmsg(message,cok,nspecial,flip)
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call packmsg(message,d0) !Pack message into 12 6-bit bytes
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d0(11)=0 !### Temporary CRC=0 ###
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d0(12)=0
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call unpackbits(d0,14,6,d1) !Unpack into 84 bits
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nbits=84
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call packbits(d1,nbits,8,d2) !Pack into 11 8-bit words
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nbytes=(nbits+7)/8
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do i=1,nbytes
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if(d2(i).lt.128) d3(i)=d2(i)
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if(d2(i).ge.128) d3(i)=d2(i)-256
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enddo
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call enc216(d3,nbits,d4,nsym2,16,2) !Convolutional code, K=16, r=1/2
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! NB: Should give nsym2 = (72+12+15)*2 = 198
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! call interleavejt9(d4,1,d5)
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d5=d4 !### TEMP ###
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call packbits(d5,nsym2,3,d6)
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! call graycode(d6,nsym2,1,d7)
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! Now insert sync symbols and add 1 to the tone numbers.
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nwave=0
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if(lwave) then
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nsps1=0
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if(minutes.eq.1) nsps1=7168
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if(minutes.eq.2) nsps1=16000
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if(minutes.eq.5) nsps1=42336
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if(minutes.eq.10) nsps1=86400
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if(minutes.eq.30) nsps1=262144
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if(nsps1.eq.0) stop 'Bad value for minutes in genjt9.'
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! Set up necessary constants
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dt=1.d0/12000.d0
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f0=1500.d0
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dfgen=12000.d0/nsps1
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phi=0.d0
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i=0
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k=0
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do j=1,81
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f=f0 +d7(j)*dfgen
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dphi=twopi*dt*f
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do i=1,nsps1
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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xphi=phi
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k=k+1
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iwave(k)=32767.0*sin(xphi)
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enddo
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enddo
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nwave=81*nsps1
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endif
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call unpackmsg(dgen,msgsent)
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return
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end subroutine genjt9
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