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