     highTone = false;
     // play LOW tone at Pulse Rate 1.5 PPS to 8.2 PPS (depending on AOA value)
     // scale number using this. http://stackoverflow.com/questions/929103/convert-a-number-range-to-another-range-maintaining-ratio
-    OldValue = AOA-20;
+    OldValue = AOA-LOW_TONE_AOA_START;
     OldRange = 40 - 1;  //(OldMax - OldMin)  
     NewRange = LOW_TONE_PPS_MAX - LOW_TONE_PPS_MIN; // (NewMax - NewMin)  
     NewValue = (((OldValue - 1) * NewRange) / OldRange) + LOW_TONE_PPS_MAX; //(((OldValue - OldMin) * NewRange) / OldRange) + NewMin

#define DYNON_SERIAL_LEN              53
#define DYNON_SKYVIEW_SERIAL_LEN      74

// AOA values & Tone Pulse Per Sec (PPS) 
#define HIGH_TONE_STALL_PPS   20      // how many PPS to play during stall
#define HIGH_TONE_AOA_STALL   90      // % (and above) where stall happens.
#define HIGH_TONE_AOA_START   70      // % (and above) where high tone starts
#define HIGH_TONE_PPS_MAX     6.5     // 6.5   
#define HIGH_TONE_PPS_MIN     1.5     // 1.5
#define HIGH_TONE_HZ          1600    // freq of high tone
//#define HIGH_TONE2_HZ         1500    // a 2nd high tone that it will cycle between (if defined)

#define LOW_TONE_AOA_SOLID    60      // % (and above) where a solid low tone is played.
#define LOW_TONE_AOA_START    20      // % (and above) where low 
#define LOW_TONE_PPS_MAX      8.5
#define LOW_TONE_PPS_MIN      1.5
#define LOW_TONE_HZ           400     // freq of low tone

#define TONE_PIN              2     // TIOA0
#define PIN_LED1              13    // internal LED for showing AOA status.

        input[inputPos]=inChar;
        inputPos++;
        cyclesWOSerialData = 0;
        //Serial.println(inChar);
        // check for dynon skyview data.
        if (inChar == '\n' && inputPos == DYNON_SKYVIEW_SERIAL_LEN && input[0]=='!' && input[1]=='1') {
          // skyview data starts with a '!1'... the D series efis has no line prefix.  
