diff --git a/CMakeLists.txt b/CMakeLists.txt
index 149b578b4..5686858b2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -383,13 +383,16 @@ set (wsjt_FSRCS
   lib/jt65_mod.f90
   lib/jt9_decode.f90
   lib/jt9fano.f90
+  lib/JTMSKsim.f90
   lib/jtmsk_decode.f90
   lib/jtmsk_short.f90
   lib/ldpcsim.f90
+  lib/ldpcwav.f90
   lib/libration.f90
   lib/lorentzian.f90
   lib/lpf1.f90
   lib/mixlpf.f90
+  lib/makepings.f90
   lib/moondopjpl.f90
   lib/morse.f90
   lib/move.f90
@@ -1018,6 +1021,9 @@ target_link_libraries (jt65 wsjt_fort wsjt_cxx)
 add_executable (ldpcsim lib/ldpcsim.f90 wsjtx.rc)
 target_link_libraries (ldpcsim wsjt_fort wsjt_cxx)
 
+add_executable (JTMSKsim lib/JTMSKsim.f90 wsjtx.rc)
+target_link_libraries (JTMSKsim wsjt_fort wsjt_cxx)
+
 add_executable (jt9 ${jt9_FSRCS} ${jt9_CXXSRCS} wsjtx.rc)
 if (${OPENMP_FOUND} OR APPLE)
   if (APPLE)
diff --git a/lib/JTMSKsim144.f90 b/lib/JTMSKsim144.f90
index 9332eb7f0..25affab2b 100644
--- a/lib/JTMSKsim144.f90
+++ b/lib/JTMSKsim144.f90
@@ -37,15 +37,15 @@ program JTMSKsim
   h=default_header(12000,NMAX)
 
   ichk=0
-  call genmsk(msg,ichk,msgsent,waveform,itype)       !Check message type
+  call genmsk(msg,ichk,msgsent,waveform,itype)   !this is genmsk144
   if(itype.lt.1 .or. itype.gt.7) then
      print*,'Illegal message'
      go to 999
   endif
 
-!  call makepings(pings,NMAX,width,sig)
-  pings=0.0
-  pings(12345:24000)=sig
+  call makepings(pings,NMAX,width,sig)
+!  pings=0.0
+!  pings(12345:24000)=sig
   do ifile=1,nfiles                  !Loop over requested number of files
      write(fname,1002) ifile         !Output filename
 1002 format('000000_',i4.4)
diff --git a/lib/genmsk144.f90 b/lib/genmsk144.f90
index cf8884454..c66336254 100644
--- a/lib/genmsk144.f90
+++ b/lib/genmsk144.f90
@@ -1,8 +1,7 @@
 subroutine genmsk144(msg0,ichk,msgsent,waveform,itype)
 
-!!!!!!!!!!!!!!!!!!!!! Experimental ldpc version
-! b11 + 128bit code + 1 zero bit = 140 bits (70ms message duration)
-! b13 + 128bit code + 2 slack + 1 zero bit = 144 bits (71ms message duration)
+!!!!!!!!!!!!!!!!!! Experimental small blocklength ldpc version
+! s8 + 48bits + s8 + 40 bits = 144 bits (72ms message duration)
 !
 ! Encode a JTMSK message
 ! Input:
@@ -36,14 +35,14 @@ subroutine genmsk144(msg0,ichk,msgsent,waveform,itype)
   integer*1 bitseq(144)                   !Tone #s, data and sync (values 0-1)
   integer*1 i1hash(4)
   integer*1 b7(7)
-  integer*1 b8(8)
+  integer*1 s8(8)
   integer*1 b11(11)
   integer*1 b13(13)
   real*8 pp(12)
   real*8 xi(864),xq(864),pi,twopi,phi,dphi
   real waveform(864)
   data b7/1,1,1,0,0,1,0/
-  data b8/0,1,1,1,0,0,1,0/
+  data s8/0,1,1,1,0,0,1,0/
   data b11/1,1,1,0,0,0,1,0,0,1,0/         !Barker 11 code
   data b13/1,1,1,1,1,0,0,1,1,0,1,0,1/     !Barker 13 code
   equivalence (ihash,i1hash)
@@ -105,7 +104,7 @@ subroutine genmsk144(msg0,ichk,msgsent,waveform,itype)
          i4=iand(i4,255)
          if(ik.eq.8) then
            im=im+1
-!           if(i4.gt.127) i4=i4-256 
+!           if(i4.gt.127) i4=i4-256
            i1Msg8BitBytes(im)=i4
            ik=0
          endif
@@ -137,9 +136,9 @@ subroutine genmsk144(msg0,ichk,msgsent,waveform,itype)
 !Create 144-bit channel vector:
 !8-bit sync word + 48 bits + 8-bit sync word + 80 bits
      bitseq=0 
-     bitseq(1:8)=b8
+     bitseq(1:8)=s8
      bitseq(9:56)=reorderedcodeword(1:48)
-     bitseq(57:64)=b8
+     bitseq(57:64)=s8
      bitseq(65:144)=reorderedcodeword(49:128)
      bitseq=2*bitseq-1