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WSJT-X/lib/fsk4hf/wsprlfsim.f90
Joe Taylor 41eedd5c3f Updates and additions to test progams. 
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7654 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2017-04-27 17:43:21 +00:00

286 lines
9.7 KiB
Fortran
Raw Blame History

program wsprlfsim
! Simulate characteristics of a potential "WSPR-LF" mode using LDPC (300,60)
! code, OQPSK modulation, and 5 minute T/R sequences.
! Reception and Demodulation algorithm:
! 1. Compute coarse spectrum; find fc1 = approx carrier freq
! 2. Mix from fc1 to 0; LPF at +/- 0.75*R
! 3. Square, FFT; find peaks near -R/2 and +R/2 to get fc2
! 4. Mix from fc2 to 0
! 5. Fit cb13 (central part of csync) to c -> lag, phase
! 6. Fit complex ploynomial for channel equalization
! 7. Get soft bits from equalized data
include 'wsprlf_params.f90'
! Q: Would it be better for central Sync array to use both I and Q channels?
character*8 arg
complex cbb(0:NZ-1) !Complex baseband waveform
complex csync(0:NZ-1) !Sync symbols only, from cbb
complex c(0:NZ-1) !Complex waveform
complex c0(0:NZ-1) !Complex waveform
complex c1(0:NZ-1) !Complex waveform
complex zz(NS+ND) !Complex symbol values (intermediate)
complex z
real xnoise(0:NZ-1) !Generated random noise
real ynoise(0:NZ-1) !Generated random noise
real rxdata(ND),llr(ND) !Soft symbols
real pp(2*NSPS) !Shaped pulse for OQPSK
real a(5) !For twkfreq1
real aa(20),bb(20) !Fitted polyco's
real t(11)
character*12 label(11)
integer*8 count0,count1,count2,count3,clkfreq
integer nc(11)
integer id(NS+ND) !NRZ values (+/-1) for Sync and Data
integer ierror(NS+ND)
integer icw(NN)
integer itone(NN)
integer*1 msgbits(KK),decoded(KK),apmask(ND),cw(ND)
! integer*1 codeword(ND)
data msgbits/0,0,1,0,0,1,1,1,1,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,1,1,0,0,0,1, &
1,1,1,0,1,1,1,1,1,1,1,0,0,1,0,0,1,1,0,1,1,0,1,0,1,1,0,0,1,1/
data label/'genwsprlf','twkfreq1 a','watterson','noise gen','getfc1w', &
'getfc2w','twkfreq1 b','xdt loop','cpolyfitw','msksoftsym', &
'bpdecode300'/
nargs=iargc()
if(nargs.ne.6) then
print*,'Usage: wsprlfsim f0(Hz) delay(ms) fspread(Hz) maxn iters snr(dB)'
print*,'Example: wsprlfsim 0 0 0 5 10 -20'
print*,'Set snr=0 to cycle through a range'
go to 999
endif
call getarg(1,arg)
read(arg,*) f0 !Generated carrier frequency
call getarg(2,arg)
read(arg,*) delay !Delta_t (ms) for Watterson model
call getarg(3,arg)
read(arg,*) fspread !Fspread (Hz) for Watterson model
call getarg(4,arg)
read(arg,*) maxn !Max nterms for polyfit
call getarg(5,arg)
read(arg,*) iters !Iterations at each SNR
call getarg(6,arg)
read(arg,*) snrdb !Specified SNR_2500
nc=0
twopi=8.0*atan(1.0)
fs=NSPS*12000.0/NSPS0 !Sample rate = 22.2222... Hz
dt=1.0/fs !Sample interval (s)
tt=NSPS*dt !Duration of "itone" symbols (s)
ts=2*NSPS*dt !Duration of OQPSK symbols (s)
baud=1.0/tt !Keying rate for "itone" symbols (baud)
txt=NZ*dt !Transmission length (s)
bandwidth_ratio=2500.0/(fs/2.0)
write(*,1000) fs,f0,delay,fspread,maxn,baud,3*baud,txt,iters
1000 format('fs:',f10.3,' f0:',f5.1,' Delay:',f4.1,' fSpread:',f5.2, &
' maxn:',i3,/'Baud:',f8.3,' BW:',f5.1,' TxT:',f6.1,' iters:',i4/)
write(*,1004)
1004 format(/' SNR sync data ser ber fer fsigma tsigma', &
' tsec'/68('-'))
do i=1,N2 !Half-sine pulse shape
pp(i)=sin(0.5*(i-1)*twopi/(2*NSPS))
enddo
t=0.
call system_clock(count0,clkfreq)
call genwsprlf(msgbits,id,icw,cbb,csync,itone)!Generate baseband waveform
call system_clock(count1,clkfreq)
t(1)=float(count1-count0)/float(clkfreq)
nc(1)=nc(1)+1
do i=0,NZ-1
write(40,4001) i,cbb(i),csync(i)
4001 format(i8,4f12.6)
enddo
call system_clock(count0,clkfreq)
a=0.
a(1)=f0
call twkfreq1(cbb,NZ,fs,a,c0) !Mix baseband to specified frequency
call system_clock(count1,clkfreq)
t(2)=float(count1-count0)/float(clkfreq)
nc(2)=nc(2)+1
isna=-20
isnb=-40
if(snrdb.ne.0.0) then
isna=nint(snrdb)
isnb=isna
endif
do isnr=isna,isnb,-1 !Loop over SNR range
if(isna.ne.isnb) snrdb=isnr
sig=sqrt(bandwidth_ratio) * 10.0**(0.05*snrdb)
if(snrdb.gt.90.0) sig=1.0
nhard=0
nhardsync=0
nfe=0
sqf=0.
sqt=0.
call system_clock(count2,clkfreq)
do iter=1,iters !Loop over requested iterations
c=c0
call system_clock(count0,clkfreq)
if(delay.ne.0.0 .or. fspread.ne.0.0) then
call watterson(c,NZ,fs,delay,fspread)
endif
call system_clock(count1,clkfreq)
t(3)=t(3)+float(count1-count0)/float(clkfreq)
nc(3)=nc(3)+1
call system_clock(count0,clkfreq)
c=sig*c !Scale to requested SNR
if(snrdb.lt.90) then
do i=0,NZ-1 !Generate gaussian noise
xnoise(i)=gran()
ynoise(i)=gran()
enddo
c=c + cmplx(xnoise,ynoise) !Add AWGN noise
endif
call system_clock(count1,clkfreq)
t(4)=t(4)+float(count1-count0)/float(clkfreq)
nc(4)=nc(4)+1
call system_clock(count0,clkfreq)
call getfc1w(c,fs,fc1) !First approx for freq
call system_clock(count1,clkfreq)
t(5)=t(5)+float(count1-count0)/float(clkfreq)
nc(5)=nc(5)+1
call system_clock(count0,clkfreq)
call getfc2w(c,csync,fs,fc1,fc2,fc3) !Refined freq
call system_clock(count1,clkfreq)
t(6)=t(6)+float(count1-count0)/float(clkfreq)
nc(6)=nc(6)+1
sqf=sqf + (fc1+fc2-f0)**2
call system_clock(count0,clkfreq)
!NB: Measured performance is about equally good using fc2 or fc3 here:
a(1)=-(fc1+fc2)
a(2:5)=0.
call twkfreq1(c,NZ,fs,a,c) !Mix c down by fc1+fc2
call system_clock(count1,clkfreq)
t(7)=t(7)+float(count1-count0)/float(clkfreq)
nc(7)=nc(7)+1
! The following may not be necessary?
! z=sum(c(3088:3503)*cb13)/208.0 !Get phase from Barker 13 vector
! z0=z/abs(z)
! c=c*conjg(z0)
call system_clock(count0,clkfreq)
!---------------------------------------------------------------- DT
! Not presently used:
amax=0.
jpk=0
iaa=0
ibb=NZ-1
do j=-20*NSPS,20*NSPS,NSPS/8
ia=j
ib=NZ-1+j
if(ia.lt.0) then
ia=0
iaa=-j
else
iaa=0
endif
if(ib.gt.NZ-1) then
ib=NZ-1
ibb=NZ-1-j
endif
z=sum(c(ia:ib)*conjg(csync(iaa:ibb)))
if(abs(z).gt.amax) then
amax=abs(z)
jpk=j
endif
enddo
xdt=jpk/fs
sqt=sqt + xdt**2
call system_clock(count1,clkfreq)
t(8)=t(8)+float(count1-count0)/float(clkfreq)
nc(8)=nc(8)+1
!-----------------------------------------------------------------
nterms=maxn
c1=c
do itry=1,20
idf=itry/2
if(mod(itry,2).eq.0) idf=-idf
nhard0=0
nhardsync0=0
ifer=1
a(1)=idf*0.00085
a(2:5)=0.
call system_clock(count0,clkfreq)
call twkfreq1(c1,NZ,fs,a,c) !Mix c1 into c
call cpolyfitw(c,pp,id,maxn,aa,bb,zz,nhs)
call system_clock(count1,clkfreq)
t(9)=t(9)+float(count1-count0)/float(clkfreq)
nc(9)=nc(9)+1
call system_clock(count0,clkfreq)
call msksoftsymw(zz,aa,bb,id,nterms,ierror,rxdata,nhard0,nhardsync0)
call system_clock(count1,clkfreq)
t(10)=t(10)+float(count1-count0)/float(clkfreq)
nc(10)=nc(10)+1
if(nhardsync0.gt.35) cycle
rxav=sum(rxdata)/ND
rx2av=sum(rxdata*rxdata)/ND
rxsig=sqrt(rx2av-rxav*rxav)
rxdata=rxdata/rxsig
ss=0.84
llr=2.0*rxdata/(ss*ss)
apmask=0
max_iterations=40
ifer=0
call system_clock(count0,clkfreq)
call bpdecode300(llr,apmask,max_iterations,decoded,niterations,cw)
call system_clock(count1,clkfreq)
t(11)=t(11)+float(count1-count0)/float(clkfreq)
nc(11)=nc(11)+1
nbadcrc=0
if(niterations.ge.0) call chkcrc10(decoded,nbadcrc)
if(niterations.lt.0 .or. count(msgbits.ne.decoded).gt.0 .or. &
nbadcrc.ne.0) ifer=1
if(ifer.eq.0) exit
enddo !Freq dither loop
nhard=nhard+nhard0
nhardsync=nhardsync+nhardsync0
nfe=nfe+ifer
if(nhardsync0+nhard0+niterations+ifer.gt.0) write(42,1045) snrdb, &
nhardsync0,nhard0,niterations,ifer,xdt
1045 format(f6.1,4i6,f8.2)
enddo
call system_clock(count3,clkfreq)
tsec=float(count3-count2)/float(clkfreq)
fsigma=sqrt(sqf/iters)
tsigma=sqrt(sqt/iters)
ser=float(nhardsync)/(NS*iters)
ber=float(nhard)/(ND*iters)
fer=float(nfe)/iters
write(*,1050) snrdb,nhardsync,nhard,ser,ber,fer,fsigma,tsigma,tsec
1050 format(f6.1,2i7,2f8.4,f7.3,2f8.2f8.3)
enddo
write(*,1060) NS*iters,ND*iters
1060 format(68('-')/6x,2i7)
write(*,1065)
1065 format(/'Timing sec frac calls'/39('-'))
do i=1,11
write(*,1070) label(i),t(i),t(i)/sum(t),nc(i)
1070 format(a12,2f9.3,i8)
enddo
write(*,1072) sum(t),1.0
1072 format(39('-')/12x,2f10.3)
999 end program wsprlfsim
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