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Updates to cwsim.

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This commit is contained in:
Joe Taylor 2024-07-18 08:33:41 -04:00
parent 13b66c111f
commit a6f8237dac
1 changed files with 21 additions and 9 deletions
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30
lib/cwsim.f90
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@ -8,16 +8,16 @@ program cwsim
integer*2 iwave(NMAX) !Generated waveform (no noise)
integer icw(500) !Encoded CW message bits
complex cspread(0:NMAX-1) !Complex amplitude for Rayleigh fading
complex cdat(NMAX) !Complex waveform
complex cdat(0:NMAX-1) !Complex waveform
real dat(NMAX) !Audio waveform
real*4 xnoise(NMAX) !Generated random noise
character*60 message
character*12 arg
nargs=iargc()
if(nargs.ne.5) then
print*,'Usage: cwsim "message" freq wpm fspread snr'
print*,'Example: cwsim "CQ CQ CQ DE K1JT K1JT K1JT" 700 20 100 -10'
if(nargs.ne.6) then
print*,'Usage: cwsim "message" freq bw wpm fspread snr'
print*,'Example: cwsim "CQ CQ CQ DE K1JT K1JT K1JT" 700 100 20 100 -10'
go to 999
endif
@ -25,13 +25,15 @@ program cwsim
call getarg(2,arg)
read(arg,*) ifreq !Audio frequency (Hz)
call getarg(3,arg)
read(arg,*) wpm !CW speed, words per minute
read(arg,*) bw !Bandwidth (Hz)
call getarg(4,arg)
read(arg,*) fspread !Doppler spread in Hz
read(arg,*) wpm !CW speed, words per minute
call getarg(5,arg)
read(arg,*) fspread !Doppler spread in Hz
call getarg(6,arg)
read(arg,*) snrdb !S/N in dB (2500 hz reference BW)
rms=100.0
rms=500.0
bandwidth_ratio=2500.0/6000.0
sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*snrdb)
twopi=8.0*atan(1.0)
@ -45,9 +47,9 @@ program cwsim
itone=0
call morse(message,icw,ncw)
call cwsig(icw,ncw,ifreq,wpm,sig,cdat)
nfft=NMAX
if(fspread.ne.0) then !Apply specified Doppler spread
nfft=NMAX
nh=nfft/2
df=12000.0/nfft
cspread(0)=1.0
@ -73,7 +75,6 @@ program cwsim
enddo
call four2a(cspread,nfft,1,1,1) !Transform to time domain
sum=0.
do i=0,nfft-1
p=real(cspread(i))**2 + aimag(cspread(i))**2
@ -86,6 +87,17 @@ program cwsim
endif
dat=aimag(cdat) + xnoise
cdat=dat
call four2a(cdat,nfft,1,-1,1) !c2c to frequency domain
ia=max(250/df,(ifreq-0.5*bw)/df)
ib=ia+bw/df
cdat(0:ia)=0.
cdat(ib:)=0.
call four2a(cdat,nfft,1,+1,1) !c2c to time domain
fac=sqrt(5000/bw)/nfft
dat=fac*real(cdat)
iwave=nint(rms*dat)
write(10) h,iwave
close(10)