1subroutine analytic(d,npts,nfft,c,pc,beq)
2
3! Convert real data to analytic signal
4
5  parameter (NFFTMAX=1024*1024)
6
7  real d(npts)              ! passband signal
8  real h(NFFTMAX/2)         ! real BPF magnitude
9  real*8 pc(5),pclast(5)    ! static phase coeffs
10  real*8 ac(5),aclast(5)    ! amp coeffs
11  real*8 fp
12
13  complex corr(NFFTMAX/2)  ! complex frequency-dependent correction
14  complex c(NFFTMAX)        ! analytic signal
15
16  logical*1 beq            ! boolean static equalizer flag
17
18  data nfft0/0/
19  data aclast/0.0,0.0,0.0,0.0,0.0/
20  data pclast/0.0,0.0,0.0,0.0,0.0/
21!  data ac/1.0,0.05532,0.11438,0.12918,0.09274/ ! amp coeffs for TS2000
22  data ac/1.0,0.0,0.0,0.0,0.0/
23
24  save corr,nfft0,h,ac,aclast,pclast,pi,t,beta
25
26  df=12000.0/nfft
27  nh=nfft/2
28  if( nfft.ne.nfft0 ) then
29     pi=4.0*atan(1.0)
30     t=1.0/2000.0
31     beta=0.1
32     do i=1,nh+1
33        ff=(i-1)*df
34        f=ff-1500.0
35        h(i)=1.0
36        if(abs(f).gt.(1-beta)/(2*t) .and. abs(f).le.(1+beta)/(2*t)) then
37           h(i)=h(i)*0.5*(1+cos((pi*t/beta )*(abs(f)-(1-beta)/(2*t))))
38        elseif( abs(f) .gt. (1+beta)/(2*t) ) then
39           h(i)=0.0
40        endif
41     enddo
42     nfft0=nfft
43  endif
44
45  if( any(aclast .ne. ac) .or. any(pclast .ne. pc) ) then
46     aclast=ac
47     pclast=pc
48!     write(*,3001) pc
49!3001 format('Phase coeffs:',5f12.6)
50     do i=1,nh+1
51        ff=(i-1)*df
52        f=ff-1500.0
53        fp=f/1000.0
54        corr(i)=ac(1)+fp*(ac(2)+fp*(ac(3)+fp*(ac(4)+fp*ac(5))))
55        pd=fp*fp*(pc(3)+fp*(pc(4)+fp*pc(5))) ! ignore 1st two terms
56        corr(i)=corr(i)*cmplx(cos(pd),sin(pd))
57     enddo
58  endif
59
60  fac=2.0/nfft
61  c(1:npts)=fac*d(1:npts)
62  c(npts+1:nfft)=0.
63  call four2a(c,nfft,1,-1,1)               !Forward c2c FFT
64
65  if( beq ) then
66    c(1:nh+1)=h(1:nh+1)*corr(1:nh+1)*c(1:nh+1)
67  else
68    c(1:nh+1)=h(1:nh+1)*c(1:nh+1)
69  endif
70
71  c(1)=0.5*c(1)                            !Half of DC term
72  c(nh+2:nfft)=0.                          !Zero the negative frequencies
73  call four2a(c,nfft,1,1,1)                !Inverse c2c FFT
74  return
75end subroutine analytic
76