10 REM frequency response of cable to charcteristic impedance
   20 PRINT TAB(30,4);"frequency response of R.F. cable to various charcteristic impedance"
   30 PROC_horizontal_axis
   40 PROC_vertical_axis
   50 PROC_horizontal_numbers
   60 PROC_vertical_numbers
   70 
   80 
   90 REM cable calculations
  100 PRINT TAB(35,23);"Calculation over 1m length of cable"
  110 REM 50ohm = 120pF/m, 300nH/m
  120 PROC_50ohm
  130 
  140 REM 75ohm = 53pF/m, 300nH/m
  150 PROC_75ohm
  160 
  170 REM 300ohm = 3.3pF/m, 300nH/m
  180 PROC_300ohm
  190 
  200 REM 450ohm = 1.48pF/m, 300nH/m
  210 PROC_450ohm
  220 
  230 REM 600ohm = 0.83pF/m, 300nH/m
  240 PROC_600ohm
  250 
  260 ORIGIN 200,200
  270 *CHDIR C:\Users\alastair\Pictures
  280 *SCREENSAVE cable_attenuation.bmp 1,1,2000,1200
  290 
  300 END
  310 
  320 
  330 REM following sub-routines for cable attenuation to signal frequency
  340 
  350 
  360 DEF PROC_50ohm
  370 MOVE 510,1200
  380 FOR x_axis = 1 TO 150 STEP 2
  390   
  400   REM cap = 120pF/metre
  410   cap = 120E-12
  420   REM ind = 300nH/metre
  430   ind = 300E-9
  440   Xc = 1/(2*PI*(x_axis*1E6)*cap)
  450   XL = (2*PI*(x_axis*1E6)*ind)
  460   current_signal = 1/(Xc + XL)
  470   signal_voltage = current_signal * Xc
  480   atten =10*LOG(1/(signal_voltage)^2)
  490   PLOT 5,(518*((LOG(x_axis))))+510, 1200 - (atten * 25.5)
  500 NEXT x_axis
  510 PRINT TAB(35,25);"1st : 50ohm @ 120pF/m, 300nH/m, ";INT(atten);"dBm @ ";x_axis;" MHz"
  520 ENDPROC
  530 
  540 DEF PROC_75ohm
  550 MOVE 510,1200
  560 FOR x_axis = 1 TO 150 STEP 2
  570   
  580   REM cap = 120pF/metre
  590   cap = 53E-12
  600   REM ind = 300nH/metre
  610   ind = 300E-9
  620   Xc = 1/(2*PI*(x_axis*1E6)*cap)
  630   XL = (2*PI*(x_axis*1E6)*ind)
  640   current_signal = 1/(Xc + XL)
  650   signal_voltage = current_signal * Xc
  660   atten =10*LOG(1/(signal_voltage)^2)
  670   PLOT 5,(518*((LOG(x_axis))))+510, 1200 - (atten * 32.1)
  680 NEXT x_axis
  690 PRINT TAB(35,26);"2nd : 75ohm @ 53pF/m, 300nH/m, ";INT(atten);"dBm @ ";x_axis;" MHz"
  700 ENDPROC
  710 
  720 
  730 
  740 DEF PROC_300ohm
  750 MOVE 510,1200
  760 FOR x_axis = 1 TO 550 STEP 10
  770   REM cap = 3.3pF/metre
  780   cap = 3.3E-12
  790   REM ind = 300nH/metre
  800   ind = 300E-9
  810   Xc = 1/(2*PI*(x_axis*1E6)*cap)
  820   XL = (2*PI*(x_axis*1E6)*ind)
  830   current_signal = 1/(Xc + XL)
  840   signal_voltage = current_signal * Xc
  850   atten =10*LOG(1/(signal_voltage)^2)
  860   PLOT 5,(437*((LOG(x_axis))))+510, 1200 - (atten * 34.2)
  870 NEXT x_axis
  880 PRINT TAB(35,27);"3rd : 300ohm @ 3.3pF/m, 300nH/m, ";INT(atten);"dBm @ ";x_axis;" MHz"
  890 ENDPROC
  900 
  910 
  920 
  930 DEF PROC_450ohm
  940 MOVE 510,1200
  950 FOR x_axis = 1 TO 550 STEP 10
  960   REM cap = 3.3pF/metre
  970   cap = 1.5E-12
  980   REM ind = 300nH/metre
  990   ind = 300E-9
 1000   Xc = 1/(2*PI*(x_axis*1E6)*cap)
 1010   XL = (2*PI*(x_axis*1E6)*ind)
 1020   current_signal = 1/(Xc + XL)
 1030   signal_voltage = current_signal * Xc
 1040   atten =10*LOG(1/(signal_voltage)^2)
 1050   PLOT 5,(437*((LOG(x_axis))))+510, 1200 - (atten * 45.6)
 1060 NEXT x_axis
 1070 PRINT TAB(35,28);"4th : 450ohm @ 1.5pF/m, 300nH/m, ";INT(atten);"dBm @ ";x_axis;" MHz"
 1080 ENDPROC
 1090 
 1100 
 1110 DEF PROC_600ohm
 1120 MOVE 510,1200
 1130 FOR x_axis = 1 TO 550 STEP 10
 1140   REM cap = 0.83pF/metre
 1150   cap = 0.83E-12
 1160   REM ind = 300nH/metre
 1170   ind = 300E-9
 1180   Xc = 1/(2*PI*(x_axis*1E6)*cap)
 1190   XL = (2*PI*(x_axis*1E6)*ind)
 1200   current_signal = 1/(Xc + XL)
 1210   signal_voltage = current_signal * Xc
 1220   atten =10*LOG(1/(signal_voltage)^2)
 1230   PLOT 5,(437*((LOG(x_axis))))+510, 1200 - (atten * 60)
 1240 NEXT x_axis
 1250 PRINT TAB(35,29);"5th : 600ohm @ 0.83pF/m, 300nH/m, ";INT(atten);"dBm @ ";x_axis;" MHz"
 1260 ENDPROC
 1270 
 1280 
 1290 
 1300 
 1310 DEF PROC_horizontal_axis
 1320 MOVE 510,430
 1330 PLOT 5,1728,430
 1340 
 1350 FOR x_axis = 1 TO 100 STEP 10
 1360   FOR y_axis = 1 TO 35 STEP 5
 1370     MOVE  (622*((LOG(x_axis))))+510,400-y_axis
 1380     PLOT 5, (622*((LOG(x_axis))))+510,400-y_axis
 1390     PLOT 5, (622*((LOG(x_axis))))+510,400+y_axis
 1400   NEXT y_axis
 1410 NEXT x_axis
 1420 ENDPROC
 1430 
 1440 
 1450 DEF PROC_horizontal_numbers
 1460 PRINT TAB(31,36);"1";TAB(41);"3";TAB(52);"5";TAB(58);"10";TAB(63);"30";TAB(66);"50";TAB(77);"1000MHz"
 1470 PRINT TAB(45,37);"Signal Frequency";TAB(100,37);"100"
 1480 PRINT TAB(102,38);"300";
 1490 PRINT TAB(105,37);"500"
 1500 ENDPROC
 1510 
 1520 
 1530 
 1540 DEF PROC_vertical_axis
 1550 MOVE 510,350
 1560 PLOT 5,510, 1200
 1570 
 1580 FOR y_axis = 1 TO 25 STEP 5
 1590   FOR x_axis = 1 TO 50
 1600     MOVE 460 - x_axis, 1200 - ((580*((LOG(y_axis)))))
 1610     PLOT 5,460 - x_axis,1200 -((580*((LOG(y_axis)))))
 1620     
 1630     PLOT 5, 460 + x_axis, 1200 -((580 * ((LOG(y_axis)))))
 1640   NEXT x_axis
 1650 NEXT y_axis
 1660 ENDPROC
 1670 
 1680 
 1690 DEF PROC_vertical_numbers
 1700 PRINT TAB(13,15);"Cable dBm loss"
 1710 PRINT TAB(13,16);"per 1 metre"
 1720 PRINT TAB(23,7);"1"
 1730 PRINT TAB(23,22);"3"
 1740 PRINT TAB(23,28);"5"
 1750 PRINT TAB(23,31);"10"
 1760 PRINT TAB(23,33);"30"
 1770 ENDPROC