Environmental Engineering Reference
In-Depth Information
10 kS/s 100 ms/div
CH1
5.00
DC
CH2
2.00
DC
CH3
2.00
DC
100:1
V/div
Full
100:1
V/div
Full
1:1
V/div
Full
CH1
CH2
CH3
20.00 V
8.00 V
8.00 V
Main: 10 k
-8.00 V
-8.00 V
-20.00 V
Expanded View
-500.0 ms
500.0 ms
CH1
CH2
CH3
20.00 V
8.00 V
8.00 V
<Z1:200>
2 ms/div
Edge CH1
AutoLevel
20.00 V
1000000001010
Sync Bit
-8.00 V
-8.00 V
-20.00 V
47.0 ms
67.0 ms
P-P
Max
Min
Avg
(C1)
(C1)
(C1)
(C1)
4.16667 V
8.75000 V
4.58333 V
6.91327 V
P-P
Max
Min
Max
(C2)
(C2)
(C2)
(C3)
4.66667 V
4.41667 V
-250.000 mV
3.41667 V
FIGURE 2.46
Waveforms collected at the RF receiver side to verify the 12-bit encoded data word.
8.75 to 4.58 V, the voltage regulator is able to maintain its output voltage at
3.3 V for around 90 ms. After this, the output voltage of the voltage regula-
tor starts to decay with the voltage across the storage capacitor.
Figure 2.46
shows the waveform of a 12-bit decoded data word that is generated by the
HT12D decoder at the receiver end. The decoded data sequence of the wave-
form is read as [0000 0000 1010]. Comparing the decoded data sequence with
the encoder data sequence at the transmitter side (starting with a synchro-
nization bit following an 8-bit address [0000 0000] and 4-bit data [1010]), the
two data sequences match each other quite accurately. The positive outcome
concluded from the experimental results verify that the RF transmitter is able
to successfully transmit five encoded digital data words to the RF receiver at
the base station in a wireless manner using the wind energy harvested by the
proposed piezoelectric wind energy harvester system.
2.2.5
Summary
A novel way of harvesting wind energy using piezoelectric material for a
low-power autonomous wind speed sensor has been proposed and demon-
strated with an experimental setup. Unlike the conventional wind turbine, the
piezoelectric wind harvester together with its related electronic circuits are
relatively smaller in size and lighter in weight; hence, it is more portable and
suitable for low-power autonomous sensors. Experimental results showed
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