Besides
the programming, this study also examines how the ultrasonic sensors functions.
All the data are gathered presented in Table 3. The table shows analysis of the
ultrasonic Sensor analog voltage value between the calculation value and
measurement value. Figure 24 illustrate the concepts of the calculation which
is followed with the formulas.
Table
3: Result of analyzing the ultrasonic sensor
No

Range
(cm)

Calculation
(mV) 1 inch= 10mV

Measured
(mV)

Error
%

1

0

0

0

0

2

5

50

42

16

3

10

100

94

6

4

15

150

142

5.3

5

20

200

193

3.5

6

25

250

245

2.0

7

30

300

296

1.3

8

35

350

346

1.1

9

40

400

396

1.0

Figure 24: Square Wave Oscillation
Figure
24 shows the usual square wave. In each time interval, the waves repeat
regularly because they are stable. The waves commute between V and V+, stop at
every stage of running time (Ta or Tb). Therefore, t is the addition of Ta and
Tb.
T
= Ta + Tb
Where
T is the period of the square wave
Ta is the interval between T1 and T2
Tb is the interval between T2 and T3
For frequencies,
T = (1/F) = 0.69 C1 [2R1 + (R2+R3)]
By using the formula above, duty
cycle can be found through the calculation steps as follows:
T off = 0.69C1
T on = 0.69C1 (R1 +R2+R3)
Duty cycle = (T on / T)
Duty cycle = (R1+R2+R3) / [(R2+R3) +2R1]
In
Table 3, the voltage values obtained from the test are slightly different from
the values shown in the ultrasonic sensor data sheet. It shows that there were
errors with the ultrasonic analog output by. In relation, Figure 25 shows the
difference between calculation value and the measured value.
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