10 REM -136dBW = 1uV
   20 uV = 10*(LOG((1E-6)^2/50))
   30 REM PRINT uV
   40 REM the "effective_Tx_power = 1" is the overall power budget for the communications channel
   50 REM for a 100watt tx with 50ohm stub antenn'a, the power budget is 1 watt, or 1% efficiency
   60 
   70 tx_power_watts = 4
   80 ant_eff_percentage_ant_RF_set_1 = 8.86
   90 ant_eff_percentage_ant_Rf_set_2 = 200
  100 path_loss_dB =  40
  110 path_loss_divider = 10^(path_loss_dB/10)
  120 overall_ant_eff =  ((ant_eff_percentage_ant_RF_set_1/100) * (ant_eff_percentage_ant_Rf_set_2/100)) * 100
  130 overall_ant_factor = overall_ant_eff / 100
  140 antenna_ERP_watts =  tx_power_watts * overall_ant_factor
  150 
  160 effective_power_budget =  antenna_ERP_watts / path_loss_divider
  170 
  180 ERP_dBW = 10*LOG( effective_power_budget)
  190 
  200 REM effective_power_budget = (antenna_ERP_watts/tx_power_watts)/2
  210 
  220 REM "freq" is the signal frequency used and is in MHz
  230 freq = 433
  240 
  250 
  260 REM "start_point_metres" equates to the starting point of test distance of the propagation path
  270 start_point_metres = 10E3
  280 
  290 REM "distance_test_metres" equates to the distance at which the signal is expected to travel
  300 distance_test_metres =50E3
  310 
  320 REM "inc_test_point_metres" is the increment point of distance on which the propagation model calculates the results
  330 inc_test_point_metres = 5E3
  340 
  350 PRINT
  360 PRINT
  370 PRINT
  380 PRINTTAB(15);" An Rx signal of ";uV;"dBW = 1uV of received signal voltage"
  390 PRINT
  400 PRINTTAB(15);" Tx power watts = ";tx_power_watts;" Watts"
  410 PRINT TAB(15);" Frequency of signal = ";freq; "MHz"
  420 PRINT TAB(15);" antenna efficiency of radio set 1 = ";ant_eff_percentage_ant_RF_set_1;"%"
  430 PRINT TAB(15);" antenna efficiency of radio set 2 = ";ant_eff_percentage_ant_Rf_set_2;"%"
  440 PRINTTAB(15);" overall antenna efficiency = ";overall_ant_eff;"%"
  450 PRINT
  460 PRINT TAB(15);" signal path loss dB = ";path_loss_dB;"dB"
  470 
  480 PRINT
  490 PRINT TAB(15);" RF power budget watts = ";effective_power_budget;"Watts"
  500 PRINT TAB(15);" RF power budget dBW   = ";ERP_dBW; "dBW"
  510 PRINT
  520 PRINT
  530 
  540 PRINT TAB(15);" Received signal power";TAB(58);" signal path com's range"
  550 PRINT
  560 
  570 FOR  t = start_point_metres TO distance_test_metres STEP inc_test_point_metres
  580   scaler = (t/(300/freq))^2
  590   PRINT TAB(15);" Rx signal = ";10*LOG(effective_power_budget/scaler);" dBW ";TAB(53);" distance = ";(t/1000);" Km  ";TAB(78);((t/1000)/1.6);" miles"
  600 NEXT
  610 ORIGIN 200,200
  620 REM *CHDIR C:\Users\alastair\Pictures\70cm
  630 REM *SCREENSAVE log_70cm_13w_mobile_repeater.bmp 1,1,2000,1100
  640