Hello! I am trying to create a device that measures the respiratory rate(RR) with a ntc thermistor. I need to know if there is a way of measuring the RR. The values that I get from the thermistor are in degrees. Could someone help me with some code or any idea on how to do this. Thank you!
This is how the values are plotted.
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Using an Arduino, the values you get is an integer with a value between 0 and 1023. What are you using and how is it wired?
Paul
That you will get after averaging.
Is the red line following RR ?
How fast can your NTC thermistor recover it's room temp resistance?
Paul
If you use two small glass bead thermistors mounted in tube and each wired into an op amp bridge circuit to maintain a fixed bead temperature then …
When breath passes in one direction then heat is transferred between beads in one direction and visa versa
The output of the op Amps will give you a reading for flow direction
This compensates partially for breath temperature etc and can be very sensitive .
Or google Honeywell low dp flow sensor ( micro bridge) , which is similar using etched resistors
Those are the peaks. I need to count those somehow. If I record for a longer period the peaks are more visible but I don't even know where to start.
start with some smoothing so you have single pics as on 1 not double as on 2. google - arduino smoothing , then convert the signal to rectangle shape, something like this - if current value > previous value serial print high else serial print low.
you need peak detection
if ( (avg [n-2) <= avg [n-1]) && (avg [n-1) > avg [n]) )
probably if avg [n] is above some threshold
after some filtering (K = 1/N, avg = 95% max in 3N iterations)
avg [n] += (samp - avg [n-1]) * K;
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