At SUSTAIN (U. Miami) we’ve used HR Wallingford wave staffs which made good data at up to 100 Hz but have been finicky and have occasional drifts, and the software is a pain to use (not to mention no integration with your own logging). We’ve also used Ocean Sensor Systems wave wires in the tank and in the field (ASIS buoys). These have worked mostly well but are relatively thick (about 0.8 mm diameter) and sample at 32 Hz at the fastest. Their founder and lead engineer also recently passed away and it’s not clear to me that their products will continue to be produced and serviced long term.
Anyone know of capacitance (or similar technology) wave probes that:
- Can sample fast (at least 50 Hz but 100 Hz would be great)
- Are thin (5 mm diameter or less)
- Can easily integrate with custom logging (e.g. analog voltage or current output would be ideal)
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Hi @milancurcic. I only have experience with OSS WaveStaffs in the field (sorry to hear the founder passed away) and they are great, but it’s true that the 32 Hz sampling frequency could be a limitation for lab experiments. Maybe @lucia.robles-diaz has some hints on the capacitance wires used for her experiments in Pythéas-IRPHE wave tank in Marseille.
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Hi @milancurcic! At the moment I don’t have much more detail than what is in the publication. DISA is the name of the company for the capacitive wire probes we used. I am including the link to the publication for more details. If I get more information on this subject I will let you know.
https://www.sciencedirect.com/science/article/abs/pii/S0997754618306952
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Hey @milancurcic and @lucia.robles-diaz , just following up on this topic.
Do you guys think that ultrasonic sensors could be a suitable replacement for wave staffs in a laboratory setup or even in the field? I was checking OSS website and they appear to offer a range of ultrasonic sensors (like this one). They have a similar sampling rate as a regular wave staff though. Also, I came across this company MaxBotix (there should be more like this), they offer a variety of low-cost ultrasonic sensor to measure water level. I didn’t check the specs but maybe it wouldn’t be too difficult to design a simple interface (Arduino, Raspberry Pi or similar) with custom sampling rate, data logger and so on?
Does anyone have some experience with those kind of sensors? What would be the pros and cons of considering ultrasonic sensors vs. capacitance wires? Maybe the noise?
Ultrasonic distance meters can work well for waves too. We’ve used Senix Toughsonic in the lab and on the buoys, though their data from buoys I barely touched so far and can’t comment on the quality. Some brief comments based on the experience from the lab:
- Wires disrupt the surface and the wave information from the shortest waves becomes useless as their wavelength approaches a few diameters of the wire. So if you have a 1-cm diameter wire, it will affect the measurement of wavelengths of several cm. There are also issues with surface tension forces on the wire itself, so the wire reading may be biased high when the water level is going down (crest passing, trough approaching). In the field on buoys, wave wires attract organic stuff. They don’t work well in spray and very foamy surface.
- Ultrasonics are remote sensors so don’t have the above issues but they do have a footprint depending on the distance from the surface and beam width angle. So overall they won’t see the smallest wavelenghts that wires can. In steep but clean waves the beam reflects away so there are dropouts in such waves. There can be crosstalk if multiple ultrasonics are placed too close together.
I tentatively plan to experiment with low-cost components and custom logging for both approaches.
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