diff --git a/CMakeLists.txt b/CMakeLists.txt index 52b69b84a..cbde4135c 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -513,6 +513,7 @@ set (wsjt_FSRCS lib/fsk4hf/ft2d.f90 lib/ft4/ft4sim.f90 lib/ft4/ft4d.f90 + lib/ft4/ft4_decode.f90 lib/ft2/cdatetime.f90 lib/ft2/ft2_decode.f90 lib/77bit/my_hash.f90 diff --git a/lib/ft4/ft4_decode.f90 b/lib/ft4/ft4_decode.f90 new file mode 100644 index 000000000..4bafea1a9 --- /dev/null +++ b/lib/ft4/ft4_decode.f90 @@ -0,0 +1,295 @@ +subroutine ft4_decode(cdatetime0,nfqso,iwave,ndecodes,mycall,hiscall,nrx,line) + + use packjt77 + include 'ft4_params.f90' + character message*37 + character c77*77 + character*61 line + character*37 decodes(100) + character*120 data_dir + character*17 cdatetime0 + character*6 mycall,hiscall,hhmmss + + complex cd2(0:NMAX/16-1) !Complex waveform + complex cb(0:NMAX/16-1) + complex cd(0:76*20-1) !Complex waveform + complex ctwk(80),ctwk2(80) + complex csymb(20) + complex cs(0:3,NN) + real s4(0:3,NN) + + real bmeta(152),bmetb(152),bmetc(152) + real s(NH1,NHSYM) + real a(5) + real llr(128),llr2(128),llra(128),llrb(128),llrc(128) + real s2(0:255) + real candidate(3,100) + real savg(NH1),sbase(NH1) + integer icos4(0:3) + integer*2 iwave(NMAX) !Generated full-length waveform + integer*1 message77(77),apmask(128),cw(128) + integer*1 hbits(152) + integer graymap(0:3) + integer ip(1) + logical unpk77_success + logical one(0:511,0:7) ! 256 4-symbol sequences, 8 bits + logical first + data icos4/0,1,3,2/ + data graymap/0,1,3,2/ + data first/.true./ + save one + + hhmmss=cdatetime0(12:17) + fs=12000.0/NDOWN !Sample rate + dt=1/fs !Sample interval after downsample (s) + tt=NSPS*dt !Duration of "itone" symbols (s) + baud=1.0/tt !Keying rate for "itone" symbols (baud) + txt=NZ*dt !Transmission length (s) + twopi=8.0*atan(1.0) + h=1.0 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading) + + if(first) then + one=.false. + do i=0,255 + do j=0,7 + if(iand(i,2**j).ne.0) one(i,j)=.true. + enddo + enddo + first=.false. + endif + + data_dir="." + fMHz=7.074 + + candidate=0.0 + ncand=0 + + nfa=375 + nfb=3000 + syncmin=1.0 + maxcand=100 +! call syncft4(iwave,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,ncand,sbase) + + call getcandidates4(iwave,375.0,3000.0,0.2,2200.0,100,savg,candidate,ncand,sbase) + ndecodes=0 + do icand=1,ncand + f0=candidate(1,icand)-1.5*37.5 + xsnr=10*log10(candidate(3,icand)) + if( f0.le.375.0 .or. f0.ge.(5000.0-375.0) ) cycle + call ft4_downsample(iwave,f0,cd2) ! downsample from 320 Sa/Symbol to 20 Sa/Symbol + sum2=sum(cd2*conjg(cd2))/(20.0*76) + if(sum2.gt.0.0) cd2=cd2/sqrt(sum2) + +! 750 samples/second here + ibest=-1 + smax=-99. + dfbest=-1. + do idf=-90,+90,5 + df=idf + a=0. + a(1)=df + ctwk=1. + call twkfreq1(ctwk,80,fs,a,ctwk2) + do istart=0,315 + call sync4d(cd2,istart,ctwk2,1,sync) + if(sync.gt.smax) then + smax=sync + ibest=istart + dfbest=df + endif + enddo + enddo + + f0=f0+dfbest +!f0=1443.75 + call ft4_downsample(iwave,f0,cb) ! downsample from 320s/Symbol to 20s/Symbol + sum2=sum(abs(cb)**2)/(20.0*76) + if(sum2.gt.0.0) cb=cb/sqrt(sum2) +!ibest=208 + cd=cb(ibest:ibest+76*20-1) + do k=1,NN + i1=(k-1)*20 + csymb=cd(i1:i1+19) + call four2a(csymb,20,1,-1,1) + cs(0:3,k)=csymb(1:4)/1e2 + s4(0:3,k)=abs(csymb(1:4)) + enddo + +! sync quality check + is1=0 + is2=0 + is3=0 + do k=1,4 + ip=maxloc(s4(:,k)) + if(icos4(k-1).eq.(ip(1)-1)) is1=is1+1 + ip=maxloc(s4(:,k+36)) + if(icos4(k-1).eq.(ip(1)-1)) is2=is2+1 + ip=maxloc(s4(:,k+72)) + if(icos4(k-1).eq.(ip(1)-1)) is3=is3+1 + enddo +! hard sync sum - max is 12 + nsync=is1+is2+is3 + + do nseq=1,3 + if(nseq.eq.1) nsym=1 + if(nseq.eq.2) nsym=2 + if(nseq.eq.3) nsym=4 + nt=2**(2*nsym) + do ks=1,76,nsym + amax=-1.0 + do i=0,nt-1 + i1=i/64 + i2=iand(i,63)/16 + i3=iand(i,15)/4 + i4=iand(i,3) + if(nsym.eq.1) then + s2(i)=abs(cs(graymap(i4),ks)) + elseif(nsym.eq.2) then + s2(i)=abs(cs(graymap(i3),ks)+cs(graymap(i4),ks+1)) + elseif(nsym.eq.4) then + s2(i)=abs(cs(graymap(i1),ks ) + & + cs(graymap(i2),ks+1) + & + cs(graymap(i3),ks+2) + & + cs(graymap(i4),ks+3) & + ) + else + print*,"Error - nsym must be 1, 2, or 4." + endif + enddo + ipt=1+(ks-1)*2 + if(nsym.eq.1) ibmax=1 + if(nsym.eq.2) ibmax=3 + if(nsym.eq.4) ibmax=7 + do ib=0,ibmax + bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - & + maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib)) + if(ipt+ib .gt.152) cycle + if(nsym.eq.1) then + bmeta(ipt+ib)=bm + elseif(nsym.eq.2) then + bmetb(ipt+ib)=bm + elseif(nsym.eq.4) then + bmetc(ipt+ib)=bm + endif + enddo + enddo + enddo + + call normalizebmet(bmeta,152) + call normalizebmet(bmetb,152) + call normalizebmet(bmetc,152) + + hbits=0 + where(bmeta.ge.0) hbits=1 + ns1=count(hbits( 1: 8).eq.(/0,0,0,1,1,0,1,1/)) + ns2=count(hbits( 73: 80).eq.(/0,0,0,1,1,0,1,1/)) + ns3=count(hbits(145:152).eq.(/0,0,0,1,1,0,1,1/)) + nsync_qual=ns1+ns2+ns3 + + sigma=0.7 + llra(1:64)=bmeta(9:72) + llra(65:128)=bmeta(81:144) + llra=2*llra/sigma**2 + llrb(1:64)=bmetb(9:72) + llrb(65:128)=bmetb(81:144) + llrb=2*llrb/sigma**2 + llrc(1:64)=bmetc(9:72) + llrc(65:128)=bmetc(81:144) + llrc=2*llrc/sigma**2 + + do isd=1,3 + if(isd.eq.1) llr=llra + if(isd.eq.2) llr=llrb + if(isd.eq.3) llr=llrc + apmask=0 + max_iterations=40 + do ibias=0,0 + llr2=llr + if(ibias.eq.1) llr2=llr+0.4 + if(ibias.eq.2) llr2=llr-0.4 + call bpdecode128_90(llr2,apmask,max_iterations,message77,cw,nharderror,niterations) + if(nharderror.ge.0) exit + enddo + if(sum(message77).eq.0) cycle + if( nharderror.ge.0 ) then + write(c77,'(77i1)') message77(1:77) + call unpack77(c77,1,message,unpk77_success) + idupe=0 + do i=1,ndecodes + if(decodes(i).eq.message) idupe=1 + enddo + if(idupe.eq.1) exit + ndecodes=ndecodes+1 + decodes(ndecodes)=message + nsnr=nint(xsnr)-15 + freq=f0 + + write(line,1000) hhmmss,nsnr,ibest/750.0,nint(freq),message +1000 format(a6,i4,f5.2,i5,' + ',1x,a37) + open(24,file='all_ft2.txt',status='unknown',position='append') + write(24,1002) cdatetime0,nsnr,ibest/750.0,nint(freq),message, & + nharderror,nsync_qual,isd,niterations + if(hhmmss.eq.' ') write(*,1002) cdatetime0,nsnr, & + ibest/750.0,nint(freq),message,nharderror,nsync_qual,isd,niterations +1002 format(a17,i4,f6.2,i5,' Rx ',a37,4i5) + close(24) + +!### Temporary: assume most recent decoded message conveys "hiscall". + i0=index(message,' ') + if(i0.ge.3 .and. i0.le.7) then + hiscall=message(i0+1:i0+6) + i1=index(hiscall,' ') + if(i1.gt.0) hiscall=hiscall(1:i1) + endif + nrx=-1 + if(index(message,'CQ ').eq.1) nrx=1 + if((index(message,trim(mycall)//' ').eq.1) .and. & + (index(message,' '//trim(hiscall)//' ').ge.4)) then + if(index(message,' 559 ').gt.8) nrx=2 + if(index(message,' R 559 ').gt.8) nrx=3 + if(index(message,' RR73 ').gt.8) nrx=4 + endif +!### + exit + + endif + enddo ! sequence estimation + enddo !candidate list + + return +end subroutine ft4_decode + +subroutine ft4_downsample(iwave,f0,c) + +! Input: i*2 data in iwave() at sample rate 12000 Hz +! Output: Complex data in c(), sampled at 1200 Hz + + include 'ft4_params.f90' + parameter (NFFT2=NMAX/16) + integer*2 iwave(NMAX) + complex c(0:NMAX/16-1) + complex c1(0:NFFT2-1) + complex cx(0:NMAX/2) + real x(NMAX) + equivalence (x,cx) + + BW=6.0*75 + df=12000.0/NMAX + x=iwave + call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain + ibw=nint(BW/df) + i0=nint(f0/df) + c1=0. + c1(0)=cx(i0) + do i=1,NFFT2/2 + arg=(i-1)*df/bw + win=exp(-arg*arg) + c1(i)=cx(i0+i)*win + c1(NFFT2-i)=cx(i0-i)*win + enddo + c1=c1/NFFT2 + call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain + c=c1(0:NMAX/16-1) + return +end subroutine ft4_downsample + diff --git a/lib/ft4/ft4d.f90 b/lib/ft4/ft4d.f90 index d1bf262c1..1f4dccd59 100644 --- a/lib/ft4/ft4d.f90 +++ b/lib/ft4/ft4d.f90 @@ -1,59 +1,28 @@ program ft4d - use crc - use packjt77 include 'ft4_params.f90' - character arg*8,message*37,c77*77,infile*80,fname*16,datetime*11 - character*37 decodes(100) - character*120 data_dir - character*90 dmsg - complex cd2(0:NMAX/16-1) !Complex waveform - complex cb(0:NMAX/16-1) - complex cd(0:76*20-1) !Complex waveform - complex csum,cterm - complex ctwk(80),ctwk2(80) - complex csymb(20) - complex cs(0:3,NN) - real s4(0:3,NN) + character*8 arg + character*17 cdatetime + character*120 data_dir + character*11 datetime + character*37 decodes(100) + character*16 fname + character*6 hiscall + character*80 infile + character*61 line + character*6 mycall + real*8 fMHz - real ps(0:8191),psbest(0:8191) - real bmeta(152),bmetb(152),bmetc(152) - real s(NH1,NHSYM) - real a(5) - real llr(128),llr2(128),llra(128),llrb(128),llrc(128) - real s2(0:255) - real candidate(3,100) - real savg(NH1),sbase(NH1) + integer ihdr(11) - integer icos4(0:3) integer*2 iwave(NMAX) !Generated full-length waveform - integer*1 message77(77),apmask(128),cw(128) - integer*1 hbits(152),hbits1(152),hbits3(152) - integer*1 s12(12) - integer graymap(0:3) - integer ip(1) - logical unpk77_success - logical one(0:511,0:7) ! 256 4-symbol sequences, 8 bits - data s12/1,1,1,2,2,2,2,2,2,1,1,1/ - data icos4/0,1,3,2/ - data graymap/0,1,3,2/ - save one fs=12000.0/NDOWN !Sample rate dt=1/fs !Sample interval after downsample (s) tt=NSPS*dt !Duration of "itone" symbols (s) baud=1.0/tt !Keying rate for "itone" symbols (baud) txt=NZ*dt !Transmission length (s) - twopi=8.0*atan(1.0) - h=1.0 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading) - - one=.false. - do i=0,255 - do j=0,7 - if(iand(i,2**j).ne.0) one(i,j)=.true. - enddo - enddo nargs=iargc() if(nargs.lt.1) then @@ -82,174 +51,11 @@ program ft4d read(10,end=999) ihdr,iwave read(infile(j2-4:j2-1),*) nutc datetime=infile(j2-11:j2-1) + cdatetime=' '//datetime close(10) - candidate=0.0 - ncand=0 - nfqso=1500 - nfa=500 - nfb=2700 - syncmin=1.0 - maxcand=100 -! call syncft4(iwave,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,ncand,sbase) - - call getcandidates4(iwave,375.0,3000.0,0.2,2200.0,100,savg,candidate,ncand,sbase) - ndecodes=0 - do icand=1,ncand - f0=candidate(1,icand)-1.5*37.5 - xsnr=1.0 - if( f0.le.375.0 .or. f0.ge.(5000.0-375.0) ) cycle - call ft4_downsample(iwave,f0,cd2) ! downsample from 320 Sa/Symbol to 20 Sa/Symbol - sum2=sum(cd2*conjg(cd2))/(20.0*76) - if(sum2.gt.0.0) cd2=cd2/sqrt(sum2) - -! 750 samples/second here - ibest=-1 - smax=-99. - dfbest=-1. - do idf=-90,+90,5 - df=idf - a=0. - a(1)=df - ctwk=1. - call twkfreq1(ctwk,80,fs,a,ctwk2) - do istart=0,315 - call sync4d(cd2,istart,ctwk2,1,sync) - if(sync.gt.smax) then - smax=sync - ibest=istart - dfbest=df - endif - enddo - enddo - - f0=f0+dfbest -!f0=1443.75 - call ft4_downsample(iwave,f0,cb) ! downsample from 320s/Symbol to 20s/Symbol - sum2=sum(abs(cb)**2)/(20.0*76) - if(sum2.gt.0.0) cb=cb/sqrt(sum2) -!ibest=208 - cd=cb(ibest:ibest+76*20-1) - do k=1,NN - i1=(k-1)*20 - csymb=cd(i1:i1+19) - call four2a(csymb,20,1,-1,1) - cs(0:3,k)=csymb(1:4)/1e2 - s4(0:3,k)=abs(csymb(1:4)) - enddo - -! sync quality check - is1=0 - is2=0 - is3=0 - do k=1,4 - ip=maxloc(s4(:,k)) - if(icos4(k-1).eq.(ip(1)-1)) is1=is1+1 - ip=maxloc(s4(:,k+36)) - if(icos4(k-1).eq.(ip(1)-1)) is2=is2+1 - ip=maxloc(s4(:,k+72)) - if(icos4(k-1).eq.(ip(1)-1)) is3=is3+1 - enddo -! hard sync sum - max is 12 - nsync=is1+is2+is3 - - do nseq=1,3 - if(nseq.eq.1) nsym=1 - if(nseq.eq.2) nsym=2 - if(nseq.eq.3) nsym=4 - nt=2**(2*nsym) - do ks=1,76,nsym - amax=-1.0 - do i=0,nt-1 - i1=i/64 - i2=iand(i,63)/16 - i3=iand(i,15)/4 - i4=iand(i,3) - if(nsym.eq.1) then - s2(i)=abs(cs(graymap(i4),ks)) - elseif(nsym.eq.2) then - s2(i)=abs(cs(graymap(i3),ks)+cs(graymap(i4),ks+1)) - elseif(nsym.eq.4) then - s2(i)=abs(cs(graymap(i1),ks ) + & - cs(graymap(i2),ks+1) + & - cs(graymap(i3),ks+2) + & - cs(graymap(i4),ks+3) & - ) - else - print*,"Error - nsym must be 1, 2, or 4." - endif - enddo - ipt=1+(ks-1)*2 - if(nsym.eq.1) ibmax=1 - if(nsym.eq.2) ibmax=3 - if(nsym.eq.4) ibmax=7 - do ib=0,ibmax - bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - & - maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib)) - if(ipt+ib .gt.152) cycle - if(nsym.eq.1) then - bmeta(ipt+ib)=bm - elseif(nsym.eq.2) then - bmetb(ipt+ib)=bm - elseif(nsym.eq.4) then - bmetc(ipt+ib)=bm - endif - enddo - enddo - enddo - - call normalizebmet(bmeta,152) - call normalizebmet(bmetb,152) - call normalizebmet(bmetc,152) - - hbits=0 - where(bmeta.ge.0) hbits=1 - ns1=count(hbits( 1: 8).eq.(/0,0,0,1,1,0,1,1/)) - ns2=count(hbits( 73: 80).eq.(/0,0,0,1,1,0,1,1/)) - ns3=count(hbits(145:152).eq.(/0,0,0,1,1,0,1,1/)) - nsync_qual=ns1+ns2+ns3 - - sigma=0.7 - llra(1:64)=bmeta(9:72) - llra(65:128)=bmeta(81:144) - llra=2*llra/sigma**2 - llrb(1:64)=bmetb(9:72) - llrb(65:128)=bmetb(81:144) - llrb=2*llrb/sigma**2 - llrc(1:64)=bmetc(9:72) - llrc(65:128)=bmetc(81:144) - llrc=2*llrc/sigma**2 - - do isd=1,3 - if(isd.eq.1) llr=llra - if(isd.eq.2) llr=llrb - if(isd.eq.3) llr=llrc - apmask=0 - max_iterations=40 - do ibias=0,0 - llr2=llr - if(ibias.eq.1) llr2=llr+0.4 - if(ibias.eq.2) llr2=llr-0.4 - call bpdecode128_90(llr2,apmask,max_iterations,message77,cw,nharderror,niterations) - if(nharderror.ge.0) exit - enddo - if(sum(message77).eq.0) cycle - if( nharderror.ge.0 ) then - write(c77,'(77i1)') message77(1:77) - call unpack77(c77,1,message,unpk77_success) - idupe=0 - do i=1,ndecodes - if(decodes(i).eq.message) idupe=1 - enddo - if(idupe.eq.1) cycle - ndecodes=ndecodes+1 - decodes(ndecodes)=message - nsnr=nint(xsnr) - write(*,1212) datetime(8:11),nsnr,ibest/750.0,f0,message,'*',nharderror,nsync_qual,isd,niterations -1212 format(a4,i4,2x,f5.3,f11.1,2x,a22,a1,i5,i5,i5,i5) - endif - enddo ! sequence estimation - enddo !candidate list + call ft4_decode(cdatetime,nfqso,iwave,ndecodes,mycall,hiscall,nrx,line) + if(ndecodes.ge.1) write(*,'(a61)') line enddo !files write(*,1120) @@ -257,73 +63,4 @@ program ft4d 999 end program ft4d -subroutine getbitmetric(ib,ps,ns,xmet) - real ps(0:ns-1) - xm1=0 - xm0=0 - do i=0,ns-1 - if( iand(i/ib,1) .eq. 1 .and. ps(i) .gt. xm1 ) xm1=ps(i) - if( iand(i/ib,1) .eq. 0 .and. ps(i) .gt. xm0 ) xm0=ps(i) - enddo - xmet=xm1-xm0 - return -end subroutine getbitmetric - -subroutine downsample4(ci,f0,co) - parameter(NI=144*160,NH=NI/2,NO=NI/16) ! downsample from 200 samples per symbol to 10 - complex ci(0:NI-1),ct(0:NI-1) - complex co(0:NO-1) - fs=12000.0 - df=fs/NI - ct=ci - call four2a(ct,NI,1,-1,1) !c2c FFT to freq domain - i0=nint(f0/df) - ct=cshift(ct,i0) - co=0.0 - co(0)=ct(0) - b=8.0 - do i=1,NO/2 - arg=(i*df/b)**2 - filt=exp(-arg) - co(i)=ct(i)*filt - co(NO-i)=ct(NI-i)*filt - enddo - co=co/NO - call four2a(co,NO,1,1,1) !c2c FFT back to time domain - return -end subroutine downsample4 - -subroutine ft4_downsample(iwave,f0,c) - -! Input: i*2 data in iwave() at sample rate 12000 Hz -! Output: Complex data in c(), sampled at 1200 Hz - - include 'ft4_params.f90' - parameter (NFFT2=NMAX/16) - integer*2 iwave(NMAX) - complex c(0:NMAX/16-1) - complex c1(0:NFFT2-1) - complex cx(0:NMAX/2) - real x(NMAX) - equivalence (x,cx) - - BW=6.0*75 - df=12000.0/NMAX - x=iwave - call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain - ibw=nint(BW/df) - i0=nint(f0/df) - c1=0. - c1(0)=cx(i0) - do i=1,NFFT2/2 - arg=(i-1)*df/bw - win=exp(-arg*arg) - c1(i)=cx(i0+i)*win - c1(NFFT2-i)=cx(i0-i)*win - enddo - c1=c1/NFFT2 - call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain - c=c1(0:NMAX/16-1) - return -end subroutine ft4_downsample diff --git a/lib/ft4/ft4sim.f90 b/lib/ft4/ft4sim.f90 index 92b09bdd0..3ed3b2553 100644 --- a/lib/ft4/ft4sim.f90 +++ b/lib/ft4/ft4sim.f90 @@ -92,12 +92,12 @@ program ft4sim enddo ! Define the instantaneous frequency waveform - dphi_peak=twopi*(hmod/2.0)/real(NSPS) + dphi_peak=twopi*hmod/real(NSPS) dphi=0.0 do j=1,NN ib=(j-1)*320 ie=ib+960-1 - dphi(ib:ie)=dphi(ib:ie)+dphi_peak*pulse*(2*itone(j)-3) + dphi(ib:ie)=dphi(ib:ie)+dphi_peak*pulse*itone(j) enddo phi=0.0 diff --git a/lib/ft4/genft4.f90 b/lib/ft4/genft4.f90 index 450efcd4d..ba906f6cd 100644 --- a/lib/ft4/genft4.f90 +++ b/lib/ft4/genft4.f90 @@ -5,7 +5,6 @@ subroutine genft4(msg0,ichk,msgsent,i4tone) ! Input: ! - msg0 requested message to be transmitted ! - ichk if ichk=1, return only msgsent -! if ichk.ge.10000, set imsg=ichk-10000 for short msg ! - msgsent message as it will be decoded ! - i4tone array of audio tone values, {0,1,2,3} @@ -21,7 +20,6 @@ subroutine genft4(msg0,ichk,msgsent,i4tone) integer*1 s12(12) integer icos4(4) real*8 xi(864),xq(864),pi,twopi -! data s12/1,1,1,2,2,2,2,2,2,1,1,1/ data icos4/0,1,3,2/ logical unpk77_success diff --git a/lib/ft4/syncft4.f90 b/lib/ft4/syncft4.f90 index db21b1e1e..4841c560e 100644 --- a/lib/ft4/syncft4.f90 +++ b/lib/ft4/syncft4.f90 @@ -26,7 +26,7 @@ subroutine syncft4(iwave,nfa,nfb,syncmin,nfqso,maxcand,s,candidate, & ! Compute symbol spectra, stepping by NSTEP steps. savg=0. tstep=NSTEP/12000.0 - df=12000.0/NFFT1 !3.125 Hz + df=12000.0/NFFT1 fac=1.0/300.0 do j=1,NHSYM ia=(j-1)*NSTEP + 1