subroutine jtmsg(msg,iflag) ! Attempts to identify false decodes in JT-style messages. ! Returns iflag with sum of bits as follows: ! ------------------------------------------ ! 1 Grid/Report invalid ! 2 Second callsign invalid ! 4 First callsign invalid ! 8 Very unlikely free text ! 16 Questionable free text ! 0 Message is probably OK ! ------------------------------------------ character*22 msg,t character*13 w1,w2,w3,w character*6 bc1,bc2,bc3 character*1 c logical c1ok,c2ok,c3ok,isdigit,isletter,isgrid4 ! Statement functions isdigit(c)=(ichar(c).ge.ichar('0')) .and. (ichar(c).le.ichar('9')) isletter(c)=(ichar(c).ge.ichar('A')) .and. (ichar(c).le.ichar('Z')) isgrid4(w)=(len_trim(w).eq.4 .and. & ichar(w(1:1)).ge.ichar('A') .and. ichar(w(1:1)).le.ichar('R') .and. & ichar(w(2:2)).ge.ichar('A') .and. ichar(w(2:2)).le.ichar('R') .and. & ichar(w(3:3)).ge.ichar('0') .and. ichar(w(3:3)).le.ichar('9') .and. & ichar(w(4:4)).ge.ichar('0') .and. ichar(w(4:4)).le.ichar('9')) t=trim(msg) !Temporary copy of msg nt=len_trim(t) ! Check for standard messages ! Insert underscore in "CQ AA " to "CQ ZZ ", "CQ nnn " to make them one word. if(t(1:3).eq.'CQ ' .and. isletter(t(4:4)) .and. & isletter(t(5:5)) .and. t(6:6).eq.' ') t(3:3)='_' if(t(1:3).eq.'CQ ' .and. isdigit(t(4:4)) .and. & isdigit(t(5:5)) .and. isdigit(t(6:6)) .and. t(7:7).eq.' ') t(3:3)='_' ! Parse first three words w1=' ' w2=' ' w3=' ' i1=index(t,' ') if(i1.gt.0) w1(1:i1-1)=t(1:i1-1) t=t(i1+1:) i2=index(t,' ') if(i2.gt.0) w2(1:i2-1)=t(1:i2-1) t=t(i2+1:) i3=index(t,' ') if(i3.gt.0) w3(1:i3-1)=t(1:i3-1) if(w1(1:3).eq.'CQ ' .or. w1(1:3).eq.'CQ_' .or. w1(1:3).eq.'DE ' .or. & w1(1:4).eq.'QRZ ') then ! CQ/DE/QRZ: Should have one good callsign in w2 and maybe a grid/rpt in w3 call chkcall(w2,bc2,c2ok) iflag=0 if(.not.c2ok) iflag=iflag+2 if(len_trim(w3).ne.0 .and. (.not.isgrid4(w3))) iflag=iflag+1 if(w1(1:3).eq.'DE ' .and. c2ok) iflag=0 if(iflag.eq.0) return endif ! Check for two calls and maybe a grid, rpt, R+rpr, RRR, or 73 iflag=0 call chkcall(w1,bc1,c1ok) call chkcall(w2,bc2,c2ok) if(.not.c1ok) iflag=iflag+4 if(.not.c2ok) iflag=iflag+2 if(len_trim(w3).ne.0 .and. (.not.isgrid4(w3)) .and. & w3(1:1).ne.'+' .and. w3(1:1).ne.'-' .and. & w3(1:2).ne.'R+' .and. w3(1:2).ne.'R-' .and. & w3(1:3).ne.'73 ' .and. w3(1:4).ne.'RRR ') iflag=iflag+1 call chkcall(w3,bc3,c3ok) ! Allow(?) non-standard messages of the form CQ AS OC K1JT if(w1(1:3).eq.'CQ_'.and.isletter(w2(1:1)).and.isletter(w2(2:2)).and. & w2(3:3).eq.' '.and.c3ok) iflag=0 if(iflag.eq.0 .or. nt.gt.13) return ! Check for plausible free text nc=0 np=0 do i=1,13 c=msg(i:i) if(c.ne.' ') nc=nc+1 !Number of non-blank characters if(c.eq.'+') np=np+1 !Number of punctuation characters if(c.eq.'-') np=np+1 if(c.eq.'.') np=np+1 if(c.eq.'/') np=np+1 if(c.eq.'?') np=np+1 enddo nb=13-nc !Number of blanks iflag=16 !Mark as potentially questionable if(nc.ge.12 .or. (nc.ge.11 .and. np.gt.0)) then iflag=8 !Unlikely free text, flag it endif ! Save messages containing some common words if(msg(1:3).eq.'CQ ') iflag=0 if(index(msg,'DE ').gt.0) iflag=0 if(index(msg,'TU ').gt.0) iflag=0 if(index(msg,' TU').gt.0) iflag=0 if(index(msg,'73 ').gt.0) iflag=0 if(index(msg,' 73').gt.0) iflag=0 if(index(msg,'TNX').gt.0) iflag=0 if(index(msg,'THX').gt.0) iflag=0 if(index(msg,'EQSL').gt.0) iflag=0 if(index(msg,'LOTW').gt.0) iflag=0 if(index(msg,'DECOD').gt.0) iflag=0 if(index(msg,'CHK').gt.0) iflag=0 if(index(msg,'CLK').gt.0) iflag=0 if(index(msg,'CLOCK').gt.0) iflag=0 if(index(msg,'LOG').gt.0) iflag=0 if(index(msg,'QRM').gt.0) iflag=0 if(index(msg,'QSY').gt.0) iflag=0 if(index(msg,'TEST').gt.0) iflag=0 if(index(msg,'CQDX').gt.0) iflag=0 if(index(msg,'CALL').gt.0) iflag=0 if(index(msg,'QRZ').gt.0) iflag=0 if(index(msg,'AUTO').gt.0) iflag=0 if(index(msg,'PHOTO').gt.0) iflag=0 if(index(msg,'HYBRID').gt.0) iflag=0 if(c1ok .and. w1(1:6).eq.bc1) iflag=0 if(c2ok .and. w2(1:6).eq.bc2) iflag=0 if(nb.ge.4) iflag=0 return end subroutine jtmsg