Hey, I'm old and have not had my coffee yet this AM. Could you do me a favor and edit your post and use those so called code tag thingies </> around your code? Code tags make things like reading your code much easier.
See:
attachInterrupt(CHANNEL_1_PIN, calcSignal, CHANGE);
Serial.begin(9600);
pause = LOW;
}
void loop()
{
//Serial.println(pulse_time);
if (pulse_time > 1750){
Serial.println("START");
endSent = LOW;
digitalWrite(12, HIGH);
while(pulse_time > 1750 ){
if(!pause){
Serial.println(analogRead(analogInPin));
}