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Add ft4 files; ft4sim works, ft4d is work in progress.

This commit is contained in:
Steve Franke 2019-01-21 19:31:54 -06:00
parent f447fe49e1
commit f2dc394c84
8 changed files with 675 additions and 15 deletions
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14
CMakeLists.txt
View File

@ -462,7 +462,7 @@ set (wsjt_FSRCS
lib/ft8/genft8.f90
lib/genmsk_128_90.f90
lib/genmsk40.f90
lib/fsk4hf/genft2.f90
lib/fsk4hf/genft4.f90
lib/genqra64.f90
lib/ft8/genft8refsig.f90
lib/genwspr.f90
@ -508,8 +508,8 @@ set (wsjt_FSRCS
lib/msk144signalquality.f90
lib/msk144sim.f90
lib/mskrtd.f90
lib/fsk4hf/ft2sim.f90
lib/fsk4hf/ft2d.f90
lib/fsk4hf/ft4sim.f90
lib/fsk4hf/ft4d.f90
lib/77bit/my_hash.f90
lib/wsprd/osdwspr.f90
lib/ft8/osd174_91.f90
@ -1261,11 +1261,11 @@ target_link_libraries (ft8sim wsjt_fort wsjt_cxx)
add_executable (msk144sim lib/msk144sim.f90 wsjtx.rc)
target_link_libraries (msk144sim wsjt_fort wsjt_cxx)
add_executable (ft2sim lib/fsk4hf/ft2sim.f90 wsjtx.rc)
target_link_libraries (ft2sim wsjt_fort wsjt_cxx)
add_executable (ft4sim lib/fsk4hf/ft4sim.f90 wsjtx.rc)
target_link_libraries (ft4sim wsjt_fort wsjt_cxx)
add_executable (ft2d lib/fsk4hf/ft2d.f90 wsjtx.rc)
target_link_libraries (ft2d wsjt_fort wsjt_cxx)
add_executable (ft4d lib/fsk4hf/ft4d.f90 wsjtx.rc)
target_link_libraries (ft4d wsjt_fort wsjt_cxx)
endif(WSJT_BUILD_UTILS)

54
lib/fsk4hf/ft2d.f90
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@ -13,6 +13,7 @@ program ft2d
complex c1(0:9),c0(0:9)
complex ccor(0:1,144)
complex csum,cterm,cc0,cc1,csync1,csync2
complex csync(16),csl(0:159)
real*8 fMHz
real a(5)
@ -26,9 +27,10 @@ program ft2d
integer*2 iwave(NMAX) !Generated full-length waveform
integer*1 message77(77),apmask(128),cw(128)
integer*1 hbits(144),hbits1(144),hbits3(144)
integer*1 s16(16)
integer*1 s16(16),s45(45)
logical unpk77_success
data s16/0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0/
data s45/0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,1,0,0,1,1,1,1,0,0,1,0,0,0,1,1,0,1,0,0,0,1,1,1,0,0/
fs=12000.0/NDOWN !Sample rate
dt=1/fs !Sample interval after downsample (s)
@ -36,7 +38,7 @@ program ft2d
baud=1.0/tt !Keying rate for "itone" symbols (baud)
txt=NZ*dt !Transmission length (s)
twopi=8.0*atan(1.0)
h=0.8 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
h=0.800 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
dphi=twopi/2*baud*h*dt*16 ! dt*16 is samp interval after downsample
dphi0=-1*dphi
@ -52,6 +54,18 @@ program ft2d
the=twopi*h/2.0
cc1=cmplx(cos(the),-sin(the))
cc0=cmplx(cos(the),sin(the))
k=0
do j=1,16
dphi1=(2*s16(j)-1)*dphi
phi1=0.0
do i=0,9
csl(k)=cmplx(cos(phi1),sin(phi1))
phi1=mod(phi1+dphi1,twopi)
k=k+1
enddo
enddo
nargs=iargc()
if(nargs.lt.1) then
print*,'Usage: ft2d [-a <data_dir>] [-f fMHz] file1 [file2 ...]'
@ -89,6 +103,22 @@ program ft2d
xsnr=1.0
if( f0.le.375.0 .or. f0.ge.(5000.0-375.0) ) cycle
call ft2_downsample(iwave,f0,c2) ! downsample from 160s/Symbol to 10s/Symbol
!c2=c2/sqrt(sum(abs(c2(0:NMAX/16-1))))
!ishift=-1
!rccbest=-99.
!do is=0,435
!rcc=0.0
! do id=10,10
! rcc=rcc+abs(sum(conjg(c2(is:is+159-id))*c2(is+id:is+159)*csl(0:159-id)*conjg(csl(id:159))))
! enddo
! if(rcc.gt.rccbest) then
! rccbest=rcc
! ishift=is
! endif
!write(21,*) is,rcc
!enddo
! 750 samples/second here
ibest=-1
sybest=-99.
@ -102,9 +132,10 @@ program ft2d
csync1=0.
cterm=1
do ib=1,16
! do ib=1,45
i1=(ib-1)*10+is
i2=i1+136*10
if(s16(ib).eq.1) then
! if(s45(ib).eq.1) then
csync1=csync1+sum(cb(i1:i1+9)*conjg(c1(0:9)))*cterm
cterm=cterm*cc1
else
@ -121,13 +152,18 @@ program ft2d
enddo
a=0.
!dfbest=1500.0-f0
a(1)=-dfbest
call twkfreq1(c2,NMAX/16,fs,a,cb)
!ibest=197
ib=ibest
cd=cb(ib:ib+144*10-1)
s2=sum(cd*conjg(cd))/(10*144)
cd=cd/sqrt(s2)
do nseq=1,5
do nseq=1,4
if( nseq.eq.1 ) then ! noncoherent single-symbol detection
sbits1=0.0
do ibit=1,144
@ -178,7 +214,7 @@ program ft2d
hbits=hbits3
endif
nsync_qual=count(hbits(1:16).eq.s16)
if(nsync_qual.lt.10) exit
! if(nsync_qual.lt.10) exit
rxdata=sbits(17:144)
rxav=sum(rxdata(1:128))/128.0
rx2av=sum(rxdata(1:128)*rxdata(1:128))/128.0
@ -186,7 +222,11 @@ program ft2d
rxdata=rxdata/rxsig
sigma=0.80
llr(1:128)=2*rxdata/(sigma*sigma)
!xllrmax=maxval(abs(llr))
!write(*,*) ifile,icand,nseq,nsync_qual
apmask=0
!apmask(1:29)=1
!llr(1:29)=xllrmax*(2*s45(17:45)-1)
max_iterations=40
do ibias=0,0
llr2=llr
@ -209,8 +249,8 @@ program ft2d
nsnr=nint(xsnr)
freq=f0+dfbest
1210 format(a11,2i4,f6.2,f12.7,2x,a22,i3)
write(*,1212) datetime(8:11),nsnr,ibest/750.0,freq,message,'*',nseq,nharderror
1212 format(a4,i4,f5.1,f11.1,2x,a22,a1,i5,i5)
write(*,1212) datetime(8:11),nsnr,ibest/750.0,freq,message,'*',nseq,nharderror,nsync_qual
1212 format(a4,i4,2x,f5.3,f11.1,2x,a22,a1,i5,i5,i5)
goto 888
endif
enddo ! nseq

2
lib/fsk4hf/ft2sim.f90
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@ -48,7 +48,7 @@ program ft2sim
twopi=8.0*atan(1.0)
fs=12000.0 !Sample rate (Hz)
dt=1.0/fs !Sample interval (s)
hmod=0.8 !Modulation index (0.5 is MSK, 1.0 is FSK)
hmod=0.800 !Modulation index (0.5 is MSK, 1.0 is FSK)
tt=NSPS*dt !Duration of symbols (s)
baud=1.0/tt !Keying rate (baud)
txt=NZ*dt !Transmission length (s)

14
lib/fsk4hf/ft4_params.f90 Normal file
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@ -0,0 +1,14 @@
! FT4 37.5 baud - 26.67 ms symbol duration
! LDPC (128,90) code
parameter (KK=90) !Information bits (77 + CRC13)
parameter (ND=64) !Data symbols
parameter (NS=12) !Sync symbols (12)
parameter (NN=NS+ND) !Total channel symbols (76)
parameter (NSPS=320) !Samples per symbol at 12000 S/s
parameter (NZ=NSPS*NN) !Samples in full 1.92 s waveform (23040)
parameter (NMAX=2.5*12000) !Samples in iwave (36,000)
parameter (NFFT1=640, NH1=NFFT1/2) !Length of FFTs for symbol spectra
parameter (NSTEP=NSPS/4) !Rough time-sync step size
parameter (NHSYM=NMAX/NSTEP-3) !Number of symbol spectra (1/4-sym steps)
parameter (NDOWN=16) !Downsample factor

317
lib/fsk4hf/ft4d.f90 Normal file
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@ -0,0 +1,317 @@
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*10-1) !Complex waveform
complex c3(0:19),c2(0:19),c1(0:19),c0(0:19)
complex ccor(0:3,76)
complex csum,cterm,cc0,cc1,csync1,csync2
complex csync(12)
real*8 fMHz
real a(5)
real rxdata(128),llr(128) !Soft symbols
real llr2(128)
real sbits(152),sbits1(152),sbits3(152)
real ps(0:8191),psbest(0:8191)
real candidates(100,2)
real savg(NH1),sbase(NH1)
integer ihdr(11)
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)
logical unpk77_success
data s12/0,0,0,1,1,1,1,1,1,0,0,0/
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=1.000 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
dphi=twopi/2*baud*h*dt*16 ! dt*16 is samp interval after downsample
dphi0=-1.5*dphi
dphi1=-0.5*dphi
dphi2=+0.5*dphi
dphi3=+1.5*dphi
phi0=0.0
phi1=0.0
phi2=0.0
phi3=0.0
do i=0,9
c3(i)=cmplx(cos(phi3),sin(phi3))
c2(i)=cmplx(cos(phi2),sin(phi2))
c1(i)=cmplx(cos(phi1),sin(phi1))
c0(i)=cmplx(cos(phi0),sin(phi0))
phi3=mod(phi1+dphi3,twopi)
phi2=mod(phi1+dphi2,twopi)
phi1=mod(phi1+dphi1,twopi)
phi0=mod(phi0+dphi0,twopi)
enddo
the=twopi*h/2.0
cc3=cmplx(cos(3*the),-sin(3*the))
cc2=cmplx(cos(the),-sin(the))
cc1=cmplx(cos(the),sin(the))
cc0=cmplx(cos(3*the),-sin(3*the))
nargs=iargc()
if(nargs.lt.1) then
print*,'Usage: ft4d [-a <data_dir>] [-f fMHz] file1 [file2 ...]'
go to 999
endif
iarg=1
data_dir="."
call getarg(iarg,arg)
if(arg(1:2).eq.'-a') then
call getarg(iarg+1,data_dir)
iarg=iarg+2
endif
call getarg(iarg,arg)
if(arg(1:2).eq.'-f') then
call getarg(iarg+1,arg)
read(arg,*) fMHz
iarg=iarg+2
endif
ncoh=1
do ifile=iarg,nargs
call getarg(ifile,infile)
j2=index(infile,'.wav')
open(10,file=infile,status='old',access='stream')
read(10,end=999) ihdr,iwave
read(infile(j2-4:j2-1),*) nutc
datetime=infile(j2-11:j2-1)
close(10)
candidates=0.0
ncand=0
call getcandidates2(iwave,375.0,3000.0,0.2,2200.0,100,savg,candidates,ncand,sbase)
ndecodes=0
do icand=1,ncand
f0=candidates(icand,1)
xsnr=1.0
if( f0.le.375.0 .or. f0.ge.(5000.0-375.0) ) cycle
call ft4_downsample(iwave,f0,cd2) ! downsample from 160s/Symbol to 10s/Symbol
! 750 samples/second here
ibest=-1
sybest=-99.
dfbest=-1.
do if=-60,+60
df=if
a=0.
a(1)=-df
call twkfreq1(cd2,NMAX/16,fs,a,cb)
do is=0,380
csync1=0.
cterm=1
do ib=1,12
i1=(ib-1)*10+is
if(s12(ib).eq.0) then
csync1=csync1+sum(cb(i1:i1+19)*conjg(c0(0:19)))*cterm
cterm=cterm*cc0
else
csync1=csync1+sum(cb(i1:i1+19)*conjg(c3(0:19)))*cterm
cterm=cterm*cc3
endif
enddo
if(abs(csync1).gt.sybest) then
ibest=is
sybest=abs(csync1)
dfbest=df
endif
enddo
enddo
a=0.
!dfbest=1500.0-f0
a(1)=-dfbest
call twkfreq1(c2,NMAX/16,fs,a,cb)
!ibest=197
ib=ibest
write(*,*) f0,f0+dfbest,ibest
goto 888
cd=cb(ib:ib+144*10-1)
s2=sum(cd*conjg(cd))/(10*144)
cd=cd/sqrt(s2)
do nseq=1,1
if( nseq.eq.1 ) then ! noncoherent single-symbol detection
sbits1=0.0
do ibit=1,76
ib=(ibit-1)*10
ccor(1,ibit)=sum(cd(ib:ib+9)*conjg(c1(0:9)))
ccor(0,ibit)=sum(cd(ib:ib+9)*conjg(c0(0:9)))
sbits1(ibit)=abs(ccor(1,ibit))-abs(ccor(0,ibit))
hbits1(ibit)=0
if(sbits1(ibit).gt.0) hbits1(ibit)=1
enddo
sbits=sbits1
hbits=hbits1
sbits3=sbits1
hbits3=hbits1
elseif( nseq.ge.2 ) then
nbit=2*nseq-1
numseq=2**(nbit)
ps=0
do ibit=nbit/2+1,144-nbit/2
ps=0.0
pmax=0.0
do iseq=0,numseq-1
csum=0.0
cterm=1.0
k=1
do i=nbit-1,0,-1
ibb=iand(iseq/(2**i),1)
csum=csum+ccor(ibb,ibit-(nbit/2+1)+k)*cterm
if(ibb.eq.0) cterm=cterm*cc0
if(ibb.eq.1) cterm=cterm*cc1
k=k+1
enddo
ps(iseq)=abs(csum)
if( ps(iseq) .gt. pmax ) then
pmax=ps(iseq)
ibflag=1
endif
enddo
if( ibflag .eq. 1 ) then
psbest=ps
ibflag=0
endif
call getbitmetric(2**(nbit/2),psbest,numseq,sbits3(ibit))
hbits3(ibit)=0
if(sbits3(ibit).gt.0) hbits3(ibit)=1
enddo
sbits=sbits3
hbits=hbits3
endif
nsync_qual=count(hbits(1:16).eq.s16)
! if(nsync_qual.lt.10) exit
rxdata=sbits(17:144)
rxav=sum(rxdata(1:128))/128.0
rx2av=sum(rxdata(1:128)*rxdata(1:128))/128.0
rxsig=sqrt(rx2av-rxav*rxav)
rxdata=rxdata/rxsig
sigma=0.80
llr(1:128)=2*rxdata/(sigma*sigma)
!xllrmax=maxval(abs(llr))
!write(*,*) ifile,icand,nseq,nsync_qual
apmask=0
!apmask(1:29)=1
!llr(1:29)=xllrmax*(2*s45(17:45)-1)
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) goto 888
ndecodes=ndecodes+1
decodes(ndecodes)=message
nsnr=nint(xsnr)
freq=f0+dfbest
1210 format(a11,2i4,f6.2,f12.7,2x,a22,i3)
write(*,1212) datetime(8:11),nsnr,ibest/750.0,freq,message,'*',nseq,nharderror,nsync_qual
1212 format(a4,i4,2x,f5.3,f11.1,2x,a22,a1,i5,i5,i5)
goto 888
endif
enddo ! nseq
888 continue
enddo !candidate list
enddo !files
write(*,1120)
1120 format("<DecodeFinished>")
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 downsample2(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 downsample2
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=4.0*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

158
lib/fsk4hf/ft4sim.f90 Normal file
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@ -0,0 +1,158 @@
program ft4sim
! Generate simulated signals for experimental "FT4" mode
use wavhdr
use packjt77
include 'ft4_params.f90' !Set various constants
parameter (NWAVE=NN*NSPS)
type(hdr) h !Header for .wav file
character arg*12,fname*17
character msg37*37,msgsent37*37
character c77*77
complex c0(0:NMAX-1)
complex c(0:NMAX-1)
real wave(NMAX)
real dphi(0:NMAX-1)
real pulse(960)
integer itone(NN)
integer*1 msgbits(77)
integer*2 iwave(NMAX) !Generated full-length waveform
! Get command-line argument(s)
nargs=iargc()
if(nargs.ne.8) then
print*,'Usage: ft4sim "message" f0 DT fdop del width nfiles snr'
print*,'Examples: ft4sim "K1ABC W9XYZ EN37" 1500.0 0.0 0.1 1.0 0 10 -18'
print*,' ft4sim "WA9XYZ/R KA1ABC/R FN42" 1500.0 0.0 0.1 1.0 0 10 -18'
print*,' ft4sim "K1ABC RR73; W9XYZ <KH1/KH7Z> -11" 300 0 0 0 25 1 -10'
go to 999
endif
call getarg(1,msg37) !Message to be transmitted
call getarg(2,arg)
read(arg,*) f0 !Frequency (only used for single-signal)
call getarg(3,arg)
read(arg,*) xdt !Time offset from nominal (s)
call getarg(4,arg)
read(arg,*) fspread !Watterson frequency spread (Hz)
call getarg(5,arg)
read(arg,*) delay !Watterson delay (ms)
call getarg(6,arg)
read(arg,*) width !Filter transition width (Hz)
call getarg(7,arg)
read(arg,*) nfiles !Number of files
call getarg(8,arg)
read(arg,*) snrdb !SNR_2500
nfiles=abs(nfiles)
twopi=8.0*atan(1.0)
fs=12000.0 !Sample rate (Hz)
dt=1.0/fs !Sample interval (s)
hmod=1.000 !Modulation index (0.5 is MSK, 1.0 is FSK)
tt=NSPS*dt !Duration of symbols (s)
baud=1.0/tt !Keying rate (baud)
txt=NZ*dt !Transmission length (s)
bandwidth_ratio=2500.0/(fs/2.0)
sig=sqrt(2*bandwidth_ratio) * 10.0**(0.05*snrdb)
if(snrdb.gt.90.0) sig=1.0
txt=NN*NSPS/12000.0
! Source-encode, then get itone()
i3=-1
n3=-1
call pack77(msg37,i3,n3,c77)
read(c77,'(77i1)') msgbits
call genft4(msg37,0,msgsent37,itone)
write(*,*)
write(*,'(a9,a37,3x,a7,i1,a1,i1)') 'Message: ',msgsent37,'i3.n3: ',i3,'.',n3
write(*,1000) f0,xdt,txt,snrdb
1000 format('f0:',f9.3,' DT:',f6.2,' TxT:',f6.1,' SNR:',f6.1)
write(*,*)
if(i3.eq.1) then
write(*,*) ' mycall hiscall hisgrid'
write(*,'(28i1,1x,i1,1x,28i1,1x,i1,1x,i1,1x,15i1,1x,3i1)') msgbits(1:77)
else
write(*,'(a14)') 'Message bits: '
write(*,'(77i1)') msgbits
endif
write(*,*)
write(*,'(a17)') 'Channel symbols: '
write(*,'(76i1)') itone
write(*,*)
call sgran()
! The filtered frequency pulse
do i=1,960
tt=(i-480.5)/320.0
pulse(i)=gfsk_pulse(1.0,tt)
enddo
! Define the instantaneous frequency waveform
dphi_peak=twopi*(hmod/2.0)/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)
enddo
phi=0.0
c0=0.0
dphi=dphi+twopi*f0*dt
do j=0,NMAX-1
c0(j)=cmplx(cos(phi),sin(phi))
phi=mod(phi+dphi(j),twopi)
enddo
c0(0:319)=c0(0:319)*(1.0-cos(twopi*(/(i,i=0,319)/)/640.0) )/2.0
c0(77*320:77*320+319)=c0(77*320:77*320+319)*(1.0+cos(twopi*(/(i,i=0,319)/)/640.0 ))/2.0
c0(78*320:)=0.
k=nint((xdt+0.25)/dt)
c0=cshift(c0,-k)
ia=k
do i=0,NMAX-1
write(21,*) i,real(c0(i)),imag(c0(i)),dphi(i)
enddo
do ifile=1,nfiles
c=c0
if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c,NMAX,NWAVE,fs,delay,fspread)
c=sig*c
ib=k
wave=real(c)
peak=maxval(abs(wave(ia:ib)))
nslots=1
if(width.gt.0.0) call filt8(f0,nslots,width,wave)
if(snrdb.lt.90) then
do i=1,NMAX !Add gaussian noise at specified SNR
xnoise=gran()
wave(i)=wave(i) + xnoise
enddo
endif
gain=100.0
if(snrdb.lt.90.0) then
wave=gain*wave
else
datpk=maxval(abs(wave))
fac=32766.9/datpk
wave=fac*wave
endif
if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped."
iwave=nint(wave)
h=default_header(12000,NMAX)
write(fname,1102) ifile
1102 format('000000_',i6.6,'.wav')
open(10,file=fname,status='unknown',access='stream')
write(10) h,iwave !Save to *.wav file
close(10)
write(*,1110) ifile,xdt,f0,snrdb,fname
1110 format(i4,f7.2,f8.2,f7.1,2x,a17)
enddo
999 end program ft4sim

68
lib/fsk4hf/genft4.f90 Normal file
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subroutine genft4(msg0,ichk,msgsent,i4tone)
! s12 + 64symbols = 76 channel symbols 2.027s message duration
!
! Encode an FT4 message
! 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}
use iso_c_binding, only: c_loc,c_size_t
use packjt77
character*37 msg0
character*37 message !Message to be generated
character*37 msgsent !Message as it will be received
character*77 c77
integer*4 i4tone(76)
integer*1 codeword(128)
integer*1 msgbits(77)
integer*1 s12(12)
real*8 xi(864),xq(864),pi,twopi
data s12/0,0,0,3,3,3,3,3,3,0,0,0/
logical unpk77_success
twopi=8.*atan(1.0)
pi=twopi/2.0
message=msg0
do i=1, 37
if(ichar(message(i:i)).eq.0) then
message(i:37)=' '
exit
endif
enddo
do i=1,37 !Strip leading blanks
if(message(1:1).ne.' ') exit
message=message(i+1:)
enddo
i3=-1
n3=-1
call pack77(message,i3,n3,c77)
call unpack77(c77,0,msgsent,unpk77_success) !Unpack to get msgsent
if(ichk.eq.1) go to 999
read(c77,"(77i1)") msgbits
call encode_128_90(msgbits,codeword)
! Grayscale mapping:
! bits tone
! 00 0
! 01 1
! 11 2
! 10 3
!Create 144-bit channel vector:
i4tone(1:12)=s12
do i=1,64
is=codeword(2*i-1)+2*codeword(2*i)
if(is.le.1) i4tone(12+i)=is
if(is.eq.2) i4tone(12+i)=3
if(is.eq.3) i4tone(12+i)=2
enddo
999 return
end subroutine genft4

63
lib/fsk4hf/getcandidates4.f90 Normal file
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subroutine getcandidates4(id,fa,fb,syncmin,nfqso,maxcand,savg,candidate, &
ncand,sbase)
! For now, hardwired to find the largest peak in the average spectrum
include 'ft2_params.f90'
real s(NH1,NHSYM)
real savg(NH1),savsm(NH1)
real sbase(NH1)
real x(NFFT1)
complex cx(0:NH1)
real candidate(3,maxcand)
integer*2 id(NMAX)
integer*1 s8(8)
integer indx(NH1)
data s8/0,1,1,1,0,0,1,0/
equivalence (x,cx)
! Compute symbol spectra, stepping by NSTEP steps.
savg=0.
tstep=NSTEP/12000.0
df=12000.0/NFFT1 !3.125 Hz
fac=1.0/300.0
do j=1,NHSYM
ia=(j-1)*NSTEP + 1
ib=ia+NSPS-1
x(1:NSPS)=fac*id(ia:ib)
x(NSPS+1:)=0.
call four2a(x,NFFT1,1,-1,0) !r2c FFT
do i=1,NH1
s(i,j)=real(cx(i))**2 + aimag(cx(i))**2
enddo
savg=savg + s(1:NH1,j) !Average spectrum
enddo
savsm=0.
do i=2,NH1-1
savsm(i)=sum(savg(i-1:i+1))/3.
enddo
nfa=fa/df
nfb=fb/df
np=nfb-nfa+1
indx=0
call indexx(savsm(nfa:nfb),np,indx)
xn=savsm(nfa+indx(nint(0.3*np)))
savsm=savsm/xn
imax=-1
xmax=-99.
do i=2,NH1-1
if(savsm(i).gt.savsm(i-1).and. &
savsm(i).gt.savsm(i+1).and. &
savsm(i).gt.xmax) then
xmax=savsm(i)
imax=i
endif
enddo
f0=imax*df
if(xmax.gt.1.2) then
ncand=ncand+1
candidate(1,ncand)=f0
endif
return
end subroutine getcandidates4