Menu

CPR Mirror offset

CPR Mirror uses a single flexible sensor (Tekscan A502), which is different than load cells used in digital scales. Because there is only a single sensor, not enclosed in a rigid system, it is subject to variance in reading because of irregular application of applied pressure due to the surface applying the force and the surface the sensor is resting on. There is also a variance in quality of manufacturing from sensor to sensors. To account for these variances from actual applied force, the APP uses an offset to correct this error and bring the reading to within 5% of actual measurements. Mirror is calibrated from 0-125 pounds. Beyond this range variance may be greater.
If the APP and interface are purchased with the Samsung Tablet accessory, this offset will be set at the factory and this procedure will not be necessary.During first uses without factory supplied tablet, or during sensor replacement, this offset should be calculated and entered using the offset feature that will displayed during APP operation .
Calculating the offset;

a.) Start the APP.
b.) Place the sensor on a scale ( a simple bathroom scale will do)
c.) Place weights of zero, 50 and 100 pounds on the sensor while it is on the scale.
(you can use your knee, or simply stand on the scale to get these values)
d.) Record the reading on mirror at zero (0), 50 pounds, and 100 pounds, and the amount of difference between the scale and Mirror.
e.) If Mirror is higher than the scale, the number is negative. If mirror is lower, the offset is positive.
f.) Add these values together and divide by two. This is the offset for this sensor.
Next you will enter the offset into Mirror.

1.) Start the APP and look in the lower right hand corner for the offset control

2.) Tapping this symbol will open the offset control. It will look like this;

By tapping the numbers shown, or tapping between the two blue lines will bring up a key board to enter your offset number.
3.) Once the key board appears as shown below , enter the numbers of your offset, and press, done and set.
(To enter a negative offset, tap the .- twice to get the negative sign to appear to enter negative numbers (example, -10.0))

Measured values for force should now be within 5 to 7 pounds of actual measured value.