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FST4/W: Disable envelope shaping at start and end of transmission when environment variable FST4_NOSHAPING=1. Works for fst4sim too.

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This commit is contained in:
Steven Franke 2021-01-18 13:47:54 -06:00
parent afee4d9a28
commit 86b0affc56
2 changed files with 80 additions and 78 deletions
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2
lib/fst4/fst4sim.f90
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@ -120,7 +120,7 @@ program fst4sim
if(fspread.gt.0.0 .or. delay.ne.0.0) call watterson(c,nwave,NZ,fs,delay,fspread)
if(fspread.lt.0.0) call lorentzian_fading(c,nwave,fs,-fspread)
c=sig*c
wave=real(c)
wave=aimag(c)
if(snrdb.lt.90) then
do i=1,nmax !Add gaussian noise at specified SNR
xnoise=gran()

32
lib/fst4/gen_fst4wave.f90
View File

@ -1,17 +1,20 @@
subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, &
icmplx,cwave,wave)
use prog_args
parameter(NTAB=65536)
real wave(nwave)
complex cwave(nwave),ctab(0:NTAB-1)
character(len=1) :: cvalue
real, allocatable, save :: pulse(:)
real, allocatable :: dphi(:)
integer hmod
integer itone(nsym)
logical first
logical first, lshape
data first/.true./
data nsps0/-99/
save first,twopi,dt,tsym,nsps0,ctab
data lshape/.true./
save first,twopi,dt,tsym,nsps0,ctab,lshape
if(first) then
twopi=8.0*atan(1.0)
@ -19,6 +22,8 @@ subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, &
phi=i*twopi/NTAB
ctab(i)=cmplx(cos(phi),sin(phi))
enddo
call get_environment_variable("FST4_NOSHAPING",cvalue,nlen)
if(nlen.eq.1 .and. cvalue.eq."1") lshape=.false.
endif
if(first.or.nsps.ne.nsps0) then
@ -52,12 +57,12 @@ subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, &
if(icmplx.eq.0) wave=0.
if(icmplx.eq.1) cwave=0.
k=0
do j=0,(nsym+2)*nsps-1
do j=nsps,(nsym+1)*nsps-1
k=k+1
i=phi*float(NTAB)/twopi
i=iand(i,NTAB-1)
if(icmplx.eq.0) then
wave(k)=real(ctab(i))
wave(k)=aimag(ctab(i))
else
cwave(k)=ctab(i)
endif
@ -66,25 +71,22 @@ subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, &
enddo
! Compute the ramp-up and ramp-down symbols
kshift=nsps
if(icmplx.eq.0) then
wave(1:nsps)=0.0
wave(nsps+1:nsps+nsps/4)=wave(nsps+1:nsps+nsps/4) * &
if(lshape) then
wave(1:nsps/4)=wave(1:nsps/4) * &
(1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0
k1=nsym*nsps+3*nsps/4+1
wave((nsym+1)*nsps+1:)=0.0
k1=(nsym-1)*nsps+3*nsps/4+1
wave(k1:k1+nsps/4)=wave(k1:k1+nsps/4) * &
(1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
wave=cshift(wave,kshift)
endif
else
cwave(1:nsps)=0.0
cwave(nsps+1:nsps+nsps/4)=cwave(nsps+1:nsps+nsps/4) * &
if(lshape) then
cwave(1:nsps/4)=cwave(1:nsps/4) * &
(1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0
k1=nsym*nsps+3*nsps/4+1
cwave((nsym+1)*nsps+1:)=0.0
k1=(nsym-1)*nsps+3*nsps/4+1
cwave(k1:k1+nsps/4)=cwave(k1:k1+nsps/4) * &
(1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
cwave=cshift(cwave,kshift)
endif
endif
return