COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	BEGIN "FM"  COMMENT BY GARY GOODMAN,  JULY 1971
C00014 ENDMK
C⊗;
BEGIN "FM"  COMMENT BY GARY GOODMAN,  JULY 1971;
REQUIRE "DPYSUB.HDR[1,PDQ]" SOURCE_FILE;
INTEGER I,IIDEL,NI,L,R,LINE,K,DPY,DPY1,DPY2;
REAL C,MF,Z,W,MI1,MI2,BEAT,ZSAVE,MAXF,MINF,DELTAF,XFACT;
REAL SAVEC;
STRING S,CMD,SBARF;
BOOLEAN POWER,DEBUG,III,STEP_MODE,SOUND;
LABEL NEXT_SET;
DEFINE CRLF="('15&'12)",   TIL="STEP 1 UNTIL",   KMAX="33",
	 DELY="(-100)", DELX="(-510)", CHRWIDTH="3", CHRHEIGHT="14";
INTEGER ARRAY DPYBUF[1:200];
REAL ARRAY J[-KMAX:KMAX];

PROCEDURE ISOHZ(INTEGER M,K; REAL F,MI);
    BEGIN INTEGER I;  REAL X,Y;
	FOR I←M TIL K DO
	    BEGIN
		Y←J[I];
		IF DEBUG THEN 
			OUTSTR(CVS(I)&":"&CVF(F)&":"&CVF(IF F<0 THEN -Y ELSE Y)&CRLF);
		IF POWER THEN Y←Y*Y ELSE Y←ABS(Y);
		Y←570*Y+DELY;
		X←ABS(XFACT*(F-MINF))+DELX;
		AIVECT(X,DELY); 
		AVECT(X,Y);
		IF F>0 AND Y-DELY>12 THEN
		    BEGIN
			AIVECT(X-4,Y-4); AVECT(X+4,Y-4);
		    END;
		F←F+MF;
	    END;
    END;

INTEGER PROCEDURE JS(REAL MI);	
    BEGIN INTEGER I,K;  REAL J0,J1,J2,W;
	K←I←IF MI<.0001 THEN 0 ELSE MI+7;   
	J[I+1]←J[I-1]←J2←0.0;  J[I]←J1←.00001;  W←2/MI;
	WHILE I≥1 DO
	    BEGIN
		J[I-1]←J0←I*W*J1-J2;
		I←I-1; J2←J1;  J1←J0;
	    END;
	W←J[0]/2;
	FOR I←2 STEP 2 UNTIL K DO W←W+J[I];
	W←.5/W;
	FOR I←0 TIL K DO J[I]←J[I]*W;
	IF K>3 THEN K←K-3;
	RETURN(K);
    END;

PROCEDURE DPYFM(REAL MI);
    BEGIN INTEGER I,K,M,MM,IX,LX;   REAL S,F;
	K←JS(MI);   
	IF III THEN DPYSET(DPYBUF)
	ELSE
	    BEGIN
		DPYBUF[1]←DPY1;   DPYBUF[2]←DPY2;
		DPYRESET(DPY);
	    END;
	DPYBIG(1);
	S←-1;
	FOR I←1 TIL K DO
	    BEGIN
		J[-I]←S*J[I];  S←-S;
	    END;
	IF R≠0 THEN ISOHZ(-K,K,C-K*MF,MI)
	ELSE
	    BEGIN
		IX←-(M←(L-1)%2);  MM←L-M;
		FOR I←MM TIL K DO
		    BEGIN
			J[IX]←J[IX]-J[-I];   IX←IX+1;
		    END;
		ISOHZ(-MM+1,K,IF L MOD 2=0 THEN 0 ELSE MF/2,MI);
	    END;
	M←2*(2+K*MF/C);  F←C/2;  LX←I←1;
	WHILE I≤M AND LX<7 DO
	    BEGIN
		S←(F-MINF)*XFACT+DELX;  IF III THEN S←S-IIDEL;
		IF S>512 THEN DONE;
		AIVECT(S-CHRWIDTH,DELY-CHRHEIGHT); DPYSST("↑");
		AIVECT(S-3*CHRWIDTH,DELY-2*CHRHEIGHT);
		IF S>-512 THEN DPYSST(CASE LX OF ("0","C"," C","2C","4C","8C","16C"));
		IF I=1 AND S>-512 THEN 
		    BEGIN
			AIVECT(S-3*CHRWIDTH,DELY-2*CHRHEIGHT);
			DPYSST("_");
			AIVECT(S-3*CHRWIDTH,DELY-3*CHRHEIGHT-6);
			DPYSST("2");
		    END;
		F←F+F;  I←I+I;  LX←LX+1;
	    END;
	DPYBIG(3);
	AIVECT(-350,-120+DELY); DPYSST("MODULATION INDEX="&CVF(MI));
	IF III THEN DPYOUT(2) ELSE DPYOUT(1);
    END;

III←DPYTST=0;
SETFORMAT(5,3);
POWER←FALSE;  IIDEL←10;

WHILE TRUE DO
    BEGIN
	IF NOT DEBUG THEN DPYTYP(-430,5,1);
	OUTSTR("STEP MODE?, ANSWER YES OR <blank>←");
	STEP_MODE←(INCHWL LAND '137="Y");
	OUTSTR(CRLF&"CARRIER←");  CMD←S←INCHWL;  C←REALSCAN(S,I);
	IF C≠0 THEN CMD←"MIN" ELSE C←SAVEC;
	
	IF CMD="C" THEN
	    BEGIN I←LOP(CMD);
		OUTSTR(CRLF&"CARRIER←");  S←INCHWL;  C←REALSCAN(S,I);
	    END;
	SAVEC←C;
	IF CMD="M" THEN
	    BEGIN I←LOP(CMD);
		OUTSTR("MOD FREQ←");  S←INCHWL;  MF←REALSCAN(S,I); 
	    END;
	IF CMD="I" THEN
	    BEGIN I←LOP(CMD);
		OUTSTR("INDEX1←");  S←INCHWL;  MI1←REALSCAN(S,I);
		OUTSTR("INDEX2←");  S←INCHWL;  MI2←REALSCAN(S,I);
	    END;
	IF CMD="N" THEN
	    BEGIN
		OUTSTR("NUMBER OF INCREMENTS←");  S←INCHWL;  NI←REALSCAN(S,I);
	    END;
	W←(MI2-MI1)/NI;  ZSAVE←MI1+1;	
	K←(MI1 MAX MI2)+4;
	MAXF←C+K*MF;
	MINF←0 MAX (C-K*MF);
	DELTAF←MAXF-MINF;   XFACT←1020/DELTAF;
	L←(2.002*C)/MF;
	BEAT←2*C-L*MF;
	R←BEAT+.1;  BEAT←BEAT MIN MF-BEAT; IF R=0 THEN BEAT←MF;
	DPYSET(DPYBUF);
	DPYBIG(3);
	AIVECT(-500,-300+DELY);  SETFORMAT(5,1);
	DPYSST("CARRIER="&CVF(C)&"    MODULATION="&CVF(MF));
	SETFORMAT(5,3);
	AIVECT(-350,-220+DELY);  DPYSST("BEAT FREQUENCY="&CVF(BEAT));
	IF III THEN DPYOUT(1);
	DPY←DPYPARS;  DPY1←DPYBUF[1];  DPY2←DPYBUF[2];
	IF MI1≠MI2 THEN FOR Z←MI1 STEP W UNTIL MI2,MI2-W STEP -W UNTIL MI1 DO
	    BEGIN LABEL ASK;
		IF ABS(MI2-Z)<.000001 THEN Z←MI2;
		DPYFM(Z);
		ZSAVE←Z;
		IF INCHRS≠-1 OR STEP_MODE THEN 
		    BEGIN
		ASK:
			OUTSTR("TYPE <cr> TO PROCEED, E<cr> TO EXIT,
S<cr> TO GET STEP="&(IF ¬STEP_MODE THEN "TRUE" ELSE "FALSE")&"←");
			IF (I←INCHWL LAND '137)="E" THEN GO TO NEXT_SET
			ELSE IF I≠0 THEN
			    BEGIN
				IF I="S" THEN STEP_MODE←NOT STEP_MODE;
				GO TO ASK;
			    END;
		    END;
	    END;
	IF ABS(ZSAVE-MI1)>.001 THEN DPYFM(MI1);
NEXT_SET:
    END;
END;;