CLS
        OPEN "COM1: 4800,N,8,1,CD0,CS0,DS0,OP0,RS,TB2048,RB2048" FOR INPUT AS #1	'open COM1 for input
        FOR i% = 1 TO 6: READ a(i%): NEXT i%	'read in scale factors for each range
        DIM ADC(6, 2)
        FOR i = 1 TO 6: FOR j = 1 TO 2: READ ADC(i, j): NEXT j: NEXT i	'read in lower & upper limits for acceptable ADC values for each range
        FOR i = 1 TO 6: READ s$(i): NEXT i	'read range labels



loop1:

        WHILE NOT EOF(1)

        a$ = INPUT$(LOC(1), #1)	'get encoded output from pcaxe
        v = VAL(RIGHT$(a$, 4))	'decode switch position
        i% = v AND 7
        IF i% < 1 OR i% > 6 THEN GOTO loop1 'discard invalid switch values & start again

        ADC% = (v AND 8184) / 8	'decode ADC reading

        CLS
        LOCATE 5, 1
        PRINT "Press 1 for noise reduced reading"
        PRINT "Press x to exit"

	  REM check if ADC value is within acceptable limits
        IF ADC% < ADC(i%, 1) OR ADC% > ADC(i%, 2) THEN LOCATE 1, 10: PRINT "consider using a different scale "

	  REM proceed with calculations
        Scale = a(i%)
        voltage = ADC% / 1023 * 5000
        dB = voltage / Scale
        dBV = dB - 93
        v = 10 ^ (dBV / 20)
        dBm = dB - 80
        power = 10 ^ (dBm / 10)

	  REM Display results
        IF v >= 1 THEN v$ = " V" ELSE IF 1000 * v >= 1 THEN v$ = " mV": v = 1000 * v ELSE v$ = " uV": v = 1000000 * v

        IF power >= 1000 THEN p$ = " W": power = power / 1000 ELSE IF power >= 1 THEN p$ = " mW" ELSE power = power * 1000: p$ = " uW"

        LOCATE 10, 1
        PRINT "Switch"
        PRINT "Position", "Scale", "ADC value"
        PRINT i%, s$(i%), ADC%
        PRINT
        PRINT
        PRINT

        PRINT "Total Measured Signal Voltage"
        PRINT

        PRINT USING "###.#"; v;
        PRINT v$; TAB(20);
        PRINT USING "###.#"; dBV;
        PRINT " dBV"
        PRINT USING "##.##^^^^"; power;
        PRINT p$; TAB(20);
        PRINT USING "###.#"; dBm;
        PRINT " dBm"
        PRINT
        PRINT
        PRINT

        PRINT "Noise Reduced Signal Voltage"
        PRINT


        PRINT USING "###.#"; v - vmin;
        PRINT v$; TAB(20);
        PRINT USING "###.#"; dBV - dBVmin;
        PRINT " dBV"
        PRINT USING "##.##^^^^"; power - powermin;
        PRINT p$; TAB(20);
        PRINT USING "###.#"; dBm - dBmmin;
        PRINT " dBm"

	  REM check keyboard for options
        b$ = INKEY$
        IF b$ = "1" THEN vmin = v: dBVmin = dBV: powermin = power: dBmmin = dBm
        IF b$ = "x" THEN END

	  REM start again & get new values
        GOTO loop1
       
        WEND

        GOTO loop1

        
       DATA 44.7,49.3,61.2,81.1,123.9,250.1
       DATA 24,1015,24,1016,24,1017,24,1018,24,1019,24,1020
       DATA "10 dB","0 dB","-20 dB","-40 dB","-60 dB","-80 dB"