Pressure sensor response
A custome wrote
1) The pressure sensitivty is about 15 bit, which corresponds to about 1/10000 or 0.01% of full scale. We have compared some wave data to a Paros pressure sensor and we are almost as good the crystal sensor.
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2) We are outputting pressure in units of dBar and not m. We are not stating this explicitly, which I realize is pretty dumb. Anyway, to convert to m you have to divide by the density of water (1.023 or thereabouts for salt water)
3) For shallow water pressure measurements it is best to enter a pressure offset using the current release of the software. The problem is that a low pressure cyclone can mean that your instrument outputs 0 pressure for the first few cm. This would mean that the instrument cannot detect it if it is submerged only a few cm. If you set the pressure offset to 30 cm, this particular problem goes away.
- Atle Lohrmann
| Quote |
| My client has asked that I provide details on the pressure measurements from an Aquadopp ADCM. Could someone tell me what the sensitivity of the sensor is, and how data is converted from raw decibars to Meters (i.e., is it possible to back calculate?). Also, I noted on the message board that problems can arise in very shallow water. How do I determine if my data is off, and how do I correct for it? Thanks |
1) The pressure sensitivty is about 15 bit, which corresponds to about 1/10000 or 0.01% of full scale. We have compared some wave data to a Paros pressure sensor and we are almost as good the crystal sensor.
" />'> 2) We are outputting pressure in units of dBar and not m. We are not stating this explicitly, which I realize is pretty dumb. Anyway, to convert to m you have to divide by the density of water (1.023 or thereabouts for salt water)
3) For shallow water pressure measurements it is best to enter a pressure offset using the current release of the software. The problem is that a low pressure cyclone can mean that your instrument outputs 0 pressure for the first few cm. This would mean that the instrument cannot detect it if it is submerged only a few cm. If you set the pressure offset to 30 cm, this particular problem goes away.
- Atle Lohrmann
| Quote |
Thanks for the reply. One other quick question - when you say 0.01% of full scale, do you mean the full scale of measurements made, or the full scale that the sensor is capable of measuring. If the latter, what is the full scale that it is capable of measuring (couldn't find that in the manual). Thanks. |
The full scale refers to the full scale over which the sensor can measure. The default scale for the different instruments are:
Aquadopp: 0-200m
Aquadopp profiler: 0-100m
EasyQ: 0-10m
Vector: 0-20m
AWAC: 0-50m
At the time of purchase, it is possible (for a small fee) to get a non-standard pressure sensor for any one of these instruments.
" />'> - Atle Lohrmann
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