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Final (?) version of test_snr, with echo_snr() moved into wsjt Fortran library.

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This commit is contained in:
Joe Taylor 2022-04-22 13:07:23 -04:00
parent 87dcde7564
commit 581ef8b6e5
3 changed files with 62 additions and 58 deletions
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1
CMakeLists.txt
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@ -382,6 +382,7 @@ set (wsjt_FSRCS
lib/demod64a.f90
lib/determ.f90
lib/downsam9.f90
lib/echo_snr.f90
lib/encode232.f90
lib/encode4.f90
lib/encode_msk40.f90

56
lib/echo_snr.f90 Normal file
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@ -0,0 +1,56 @@
subroutine echo_snr(sa,sb,fspread0,blue,red,snrdb,db_err,fpeak,snr_detect)
parameter (NZ=4096)
real sa(NZ)
real sb(NZ)
real blue(NZ)
real red(NZ)
integer ipkv(1)
equivalence (ipk,ipkv)
df=12000.0/32768.0
wh=0.5*fspread0+10.0
i1=nint((1500.0 - 2.0*wh)/df) - 2048
i2=nint((1500.0 - wh)/df) - 2048
i3=nint((1500.0 + wh)/df) - 2048
i4=nint((1500.0 + 2.0*wh)/df) - 2048
call pctile(sb(i1),i2-i1,50,r0)
call pctile(sb(i3+1),i4-i3,50,r1)
scale=(r1-r0)/(0.5*(i3+i4) - 0.5*(i1+i2))
do i=1,NZ
x=i
y=r0 + scale*(i-0.5*(i1+i2))
blue(i)=sa(i)/y
red(i)=sb(i)/y
! write(13,1100) i,i*df+750.0,sb(i),y,red(i)
!1100 format(i6,f10.2,2f10.2,f10.6)
enddo
! baseline=(sum(sb(i1:i2-1)) + sum(sb(i3+1:i4)))/(i2+i4-i1-i3)
! blue=sa/baseline
! red=sb/baseline
psig=sum(red(i2:i3)-1.0)
pnoise_2500 = 2500.0/df
snrdb=db(psig/pnoise_2500)
smax=0.
mh=max(1,nint(0.2*fspread0/df))
do i=i2,i3
ssum=sum(red(i-mh:i+mh))
if(ssum.gt.smax) then
smax=ssum
ipk=i
endif
enddo
fpeak=ipk*df - 750.0
call averms(red(i1:i2-1),i2-i1,-1,ave1,rms1)
call averms(red(i3+1:i4),i4-i3,-1,ave2,rms2)
perr=0.707*(rms1+rms2)*sqrt(float(i2-i1+i4-i3))
snr_detect=psig/perr
db_err=99.0
if(psig.gt.perr) db_err=snrdb - db((psig-perr)/pnoise_2500)
return
end subroutine echo_snr

63
lib/test_snr.f90
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@ -35,13 +35,12 @@ program test_snr
nfsample=h%nsamrate
df=12000.0/NFFT
s=0.
fac=1.0/NMAX
do iping=1,npings
read(10) id2(1:NMAX)
x(1:NMAX)=id2(1:NMAX)
x(NMAX+1:)=0.
rms=sqrt(dot_product(x(1:NMAX),x(1:NMAX))/NMAX)
x(1:NMAX)=fac*id2(1:NMAX)
x(NMAX+1:)=0.
call four2a(x,NFFT,1,-1,0)
do i=1,8192 !Accumulate spectrum 0 - 3 kHz
s(i)=s(i) + real(c(i))**2 + aimag(c(i))**2
@ -53,14 +52,7 @@ program test_snr
call echo_snr(sa,sb,fspread0,blue,red,snrdb,db_err,fpeak,snr_detect)
nsum=npings
nqual=0
if(nsum.ge.2 .and. nsum.lt.4) nqual=(snr_detect-4)/5
if(nsum.ge.4 .and. nsum.lt.8) nqual=(snr_detect-3)/4
if(nsum.ge.8 .and. nsum.lt.12) nqual=(snr_detect-3)/3
if(nsum.ge.12) nqual=(snr_detect-2.5)/2.5
if(nqual.lt.0) nqual=0
if(nqual.gt.10) nqual=10
nqual=min(10,int(snr_detect-4.0))
write(*,1010) fspread0,snrdb0,snrdb,snrdb-snrdb0,db_err,fpeak, &
snr_detect,nqual
@ -69,52 +61,7 @@ program test_snr
do i=1,8192
write(12,1100) i*df,s(i)
1100 format(f10.3,e12.3)
1100 format(f10.3,e15.6)
enddo
999 end program test_snr
subroutine echo_snr(sa,sb,fspread0,blue,red,snrdb,db_err,fpeak,snr_detect)
parameter (NZ=4096)
real sa(NZ)
real sb(NZ)
real blue(NZ)
real red(NZ)
integer ipkv(1)
equivalence (ipk,ipkv)
df=12000.0/32768.0
wh=0.5*fspread0+10.0
i1=nint((1500.0 - 2.0*wh)/df) - 2048
i2=nint((1500.0 - wh)/df) - 2048
i3=nint((1500.0 + wh)/df) - 2048
i4=nint((1500.0 + 2.0*wh)/df) - 2048
baseline=(sum(sb(i1:i2-1)) + sum(sb(i3+1:i4)))/(i2+i4-i1-i3)
blue=sa/baseline
red=sb/baseline
psig=sum(red(i2:i3)-1.0)
pnoise_2500 = 2500.0/df
snrdb=db(psig/pnoise_2500)
smax=0.
mh=max(1,nint(0.2*fspread0/df))
do i=i2,i3
ssum=sum(red(i-mh:i+mh))
if(ssum.gt.smax) then
smax=ssum
ipk=i
endif
enddo
fpeak=ipk*df - 750.0
call averms(red(i1:i2-1),i2-i1,-1,ave1,rms1)
call averms(red(i3+1:i4),i4-i3,-1,ave2,rms2)
perr=0.707*(rms1+rms2)*sqrt(float(i2-i1+i4-i3))
snr_detect=psig/perr
db_err=99.0
if(psig.gt.perr) db_err=snrdb - db((psig-perr)/pnoise_2500)
return
end subroutine echo_snr