From bd0d414365fe94a067a0067b16763a365dd76014 Mon Sep 17 00:00:00 2001
From: Steven Franke <s.j.franke@icloud.com>
Date: Sun, 22 Apr 2018 19:51:31 +0000
Subject: [PATCH] More work on a simulator for dpsk with root-raised-cosine
 pulses.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8632 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
---
 lib/fsk4hf/genwsprdpsk.f90 | 12 +++++++-----
 lib/fsk4hf/wsprdpsksim.f90 | 14 ++++----------
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/lib/fsk4hf/genwsprdpsk.f90 b/lib/fsk4hf/genwsprdpsk.f90
index 353ef1339..022bd8a4d 100644
--- a/lib/fsk4hf/genwsprdpsk.f90
+++ b/lib/fsk4hf/genwsprdpsk.f90
@@ -14,7 +14,7 @@ subroutine genwsprdpsk(msg,msgsent,imessage)
   logical first
   integer ipreamble(16)                      !Freq estimation preamble
   integer isync(32)                          !Long sync vector
-  integer imessage(NN)
+  integer imessage(NN)                     
   data ipreamble/1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,1/
   data first/.true./
   data iuniqueword0/z'30C9E8AD'/
@@ -47,11 +47,13 @@ write(*,'(50i1,1x,14i1,1x,4i1)') msgbits
 
   call encode204(msgbits,codeword)      !Encode the test message
 
-! Message structure:
-! d100 p16 d100 
-  imessage(1:100)=codeword(1:100)
-  imessage(101:132)=isync
+  imessage(1)=1                         !reference bit
+  imessage(2:101)=codeword(1:100)
+  imessage(102:132)=isync(1:31)         !only use 31 of the sync bits 
   imessage(133:232)=codeword(101:200)
+  do i=2,232
+    imessage(i)=mod(imessage(i-1)+imessage(i),2)
+  enddo
 
   return
 end subroutine genwsprdpsk
diff --git a/lib/fsk4hf/wsprdpsksim.f90 b/lib/fsk4hf/wsprdpsksim.f90
index e4b2558cf..80f7dff13 100644
--- a/lib/fsk4hf/wsprdpsksim.f90
+++ b/lib/fsk4hf/wsprdpsksim.f90
@@ -15,7 +15,6 @@ program wsprdpsksim
   complex cwav(0:NMAX-1)
   real*8 fMHz
   integer imessage(NN)
-  integer idemess(NN)                    !Differentially encoded message
   integer*2 iwave(NMAX)                  !Generated full-length waveform  
 
 ! Get command-line argument(s)
@@ -54,17 +53,12 @@ program wsprdpsksim
   txt=NN*NSPS0/12000.0
 
   call genwsprdpsk(msg,msgsent,imessage)       !Encode the message, get itone
+  imessage=2*imessage-1
   write(*,1000) f0,xdt,txt,snrdb,fspread,delay,nfiles,msgsent
 1000 format('f0:',f9.3,'   DT:',f6.2,'   txt:',f6.1,'   SNR:',f6.1,    &
           '   fspread:',f6.1,'   delay:',f6.1,'  nfiles:',i3,2x,a22)
 
-! Assume 0'th message bit is 0
-  imessage=2*imessage-1
-  idemess(1)=-1*imessage(1)
-  do i=2,NN
-    idemess(i)=imessage(i-1)*imessage(i)
-  enddo
-
+ 
   beta=1.0   ! excess bandwidth
   if(nwav.eq.0) then
      df=fs/(NMAX/NDOWN)                      !
@@ -84,7 +78,7 @@ program wsprdpsksim
      istart=xdt/dt
      c0=0.0
      do i=1,NN
-       c0(istart+(i-1)*200)=idemess(i)
+       c0(istart+(i-1)*200)=imessage(i)
      enddo
      call four2a(c0,NMAX/NDOWN,1,1,1)
      c0=c0*conjg(c)
@@ -141,7 +135,7 @@ write(*,*) 'sample SNR: ',10*log10(snrtest)+10*log10(0.4/2.5)
      istart=xdt/dt
      c0wav=0.0
      do i=1,NN
-       c0wav(istart+(i-1)*200*NDOWN)=idemess(i)
+       c0wav(istart+(i-1)*200*NDOWN)=imessage(i)
      enddo
      call four2a(c0wav,NMAX,1,1,1)
      c0wav=c0wav*conjg(cwav)