Table 2 - Calibration Data
Calibration
The calibration of the AIRRS™ module is dependent on how the data is used in
your code. For threshold type applications, calibration involves determining
the distance required and measuring the voltage at that distance, allowing for
some variations in measurement. In distance measuring applications the
relation between voltage level and distance is non-linear, either a “look up”
table or a suitable algorithm must be used. The voltage levels (representing
distance) will vary slightly from unit to unit. A small survey of randomly
selected devices was done and the following data was gathered. The columns
‘Distance’ and ‘Average Voltage’ in the sample data provided can be used as a
look up table. This data is shown below (graph 1).
Distance Sample
Sample
Sample Average
(cm)
#1
#2
#3
Voltage
10
2.040
2.054
2.008
2.034
15
2.797
2.852
2.840
2.830
20
2.590
2.634
2.606
2.610
25
2.327
2.372
2.350
2.350
30
2.036
2.087
2.067
2.063
35
1.777
1.831
1.810
1.806
40
1.555
1.607
1.587
1.583
45
1.384
1.442
1.406
1.411
50
1.253
1.292
1.274
1.273
55
1.118
1.179
1.164
1.154
60
1.024
1.081
1.047
1.051
65
0.952
1.005
0.971
0.976
70
0.876
0.932
0.902
0.903
75
0.822
0.868
0.847
0.846
80
0.752
0.799
0.789
0.780
85
0.687
0.761
0.751
0.733
90
0.621
0.718
0.703
0.681
95
0.627
0.677
0.666
0.657
100
0.586
0.645
0.636
0.622
105
0.570
0.626
0.608
0.601
110
0.532
0.569
0.590
0.564
115
0.509
0.562
0.545
0.539
120
0.508
0.517
0.525
0.517
125
0.452
0.498
0.489
0.480
130
0.448
0.498
0.489
0.478
135
0.431
0.478
0.471
0.460
140
0.392
0.444
0.452
0.429
145
0.353
0.421
0.429
0.401
150
0.342
0.407
0.432
0.394
155
0.333
0.401
0.411
0.382
160
0.353
0.386
0.371
0.370
165
0.335
0.364
0.369
0.356
170
0.295
0.364
0.355
0.338
175
0.296
0.344
0.351
0.330
180
0.281
0.341
0.341
0.321
185
0.266
0.318
0.329
0.304
190
0.139
0.295
0.310
0.248
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AIRRS+ Manual v1.7
