10 REM BPBACK.BAS
15 CLS
20 PRINT "A PROG TO RECREATE THE LOWPASS PROTOTYPE FROM BANDPASS VALUES"
30 PRINT "WRITTEN 24 APRIL 1997 BY RUSS KINCAID"
40 PRINT
50 PRINT"IF SOME ELEMENTS WERE IMPEDANCE TRANSFORMED USING TAPPED INDUCTORS"
52 PRINT"THE PROTOTYPE VALUES FOR THOSE ELEMENTS MAY NOT BE CORRECT":PRINT
80 PI=3.14162
90 INPUT"SOURCE OR LOAD RESISTANCE=";RIN
92 INPUT"WILL YOU ENTER F1,F2 (1) OR F0 AND BANDWIDTH (2)";Y
94 ON Y GOTO 120,100
100 INPUT"BANDPASS CENTER FREQ";F0
110 INPUT"BANDWIDTH=";BW
114 GOTO 130
120 INPUT"BANDEDGE FREQ (F1,F2)";F1,F2
122 IF F0=0 THEN F0=SQR(F1*F2)
124 IF BW=0 THEN BW=F2-F1
130 INPUT"NUMBER OF POLES";N
132 PRINT:PRINT"FOR SERIES TUNED ELEMENTS, GIVE THE INDUCTOR ONLY."
133 PRINT"FOR PARALLEL TUNED ELEMENTS, GIVE THE CAPACITOR ONLY."
135 PRINT"IF CAP INPUT, L1=0 AND IF L INPUT, C1=0 ETC."
140 FOR J=1 TO N
144 PRINT"SECTION ";J
150 INPUT"CAP VALUE=";C(J)
160 INPUT"INDUCTOR VALUE=";L(J)
170 IF L(J)=0 THEN C(J)=C(J)*2*PI*RIN*BW:PRINT J,"C(";J;")=";C(J):GOTO 190
180 IF C(J)=0 THEN L(J)=L(J)*2*PI*BW/RIN
185 PRINT J,"L(";J;")=";L(J)
190 NEXT J: INPUT"MORE?";Y$:IF LEFT$(Y$,1)="Y" OR LEFT$(Y$,1)="y" THEN 90
195 CHAIN "FILTMENU"
200 END
(
geocities.com/russlk)