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Wireless sensor node for surface seawater density measurements.

Baronti F, Fantechi G, Roncella R, Saletti R - Sensors (Basel) (2012)

Bottom Line: The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller.Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network.The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Ingegneria dell'Informazione: Elettronica, Informatica, Telecomunicazioni, University of Pisa, Pisa, Italy. f.baronti@iet.unipi.it

ABSTRACT
An electronic meter to measure surface seawater density is presented. It is based on the measurement of the difference in displacements of a surface level probe and a weighted float, which according to Archimedes' law depends on the density of the water. The displacements are simultaneously measured using a high-accuracy magnetostrictive sensor, to which a custom electronic board provides a wireless connection and power supply so that it can become part of a wireless sensor network. The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller. Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network. The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

Show MeSH
Displacement readings of the two probes in at-sea test experiments. Note the large oscillations due to the waves and the differential reading that gives the weighted float draft. The solid line shows the progressive average of the draft that filters out the effect of the oscillations after just few seconds of measurement.
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f5-sensors-12-02954: Displacement readings of the two probes in at-sea test experiments. Note the large oscillations due to the waves and the differential reading that gives the weighted float draft. The solid line shows the progressive average of the draft that filters out the effect of the oscillations after just few seconds of measurement.

Mentions: The density meter node was also tested at sea, by hanging it from a pier in a marina. Several acquisitions were performed. An example of the results obtained is reported in Figure 5, which shows the position of the probes along the sensor rod referring to the sensor head position. It is easy to see how these displacements are affected by strong oscillations due to the sea waves. This condition is the worst possible, because the sensor is placed on a fixed pier and the displacement measurements are fully affected by the wave dynamics. Should we repeat the measurements with the sensor placed in a floating container, we would experience a smaller influence of the waves on the displacement measurements, because both the sensor head and the probes are moving with the waves. Therefore, we could expect more stable and less sensitive results, particularly in the difference between the displacement values of the two probes.


Wireless sensor node for surface seawater density measurements.

Baronti F, Fantechi G, Roncella R, Saletti R - Sensors (Basel) (2012)

Displacement readings of the two probes in at-sea test experiments. Note the large oscillations due to the waves and the differential reading that gives the weighted float draft. The solid line shows the progressive average of the draft that filters out the effect of the oscillations after just few seconds of measurement.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376632&req=5

f5-sensors-12-02954: Displacement readings of the two probes in at-sea test experiments. Note the large oscillations due to the waves and the differential reading that gives the weighted float draft. The solid line shows the progressive average of the draft that filters out the effect of the oscillations after just few seconds of measurement.
Mentions: The density meter node was also tested at sea, by hanging it from a pier in a marina. Several acquisitions were performed. An example of the results obtained is reported in Figure 5, which shows the position of the probes along the sensor rod referring to the sensor head position. It is easy to see how these displacements are affected by strong oscillations due to the sea waves. This condition is the worst possible, because the sensor is placed on a fixed pier and the displacement measurements are fully affected by the wave dynamics. Should we repeat the measurements with the sensor placed in a floating container, we would experience a smaller influence of the waves on the displacement measurements, because both the sensor head and the probes are moving with the waves. Therefore, we could expect more stable and less sensitive results, particularly in the difference between the displacement values of the two probes.

Bottom Line: The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller.Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network.The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Ingegneria dell'Informazione: Elettronica, Informatica, Telecomunicazioni, University of Pisa, Pisa, Italy. f.baronti@iet.unipi.it

ABSTRACT
An electronic meter to measure surface seawater density is presented. It is based on the measurement of the difference in displacements of a surface level probe and a weighted float, which according to Archimedes' law depends on the density of the water. The displacements are simultaneously measured using a high-accuracy magnetostrictive sensor, to which a custom electronic board provides a wireless connection and power supply so that it can become part of a wireless sensor network. The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller. Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network. The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

Show MeSH