Is there a calibration on Data acquisition?
Answer:
I am not sure what type of system you are using, but I have used systems that needed to be calibrated and I have used systems that did not need to be calibrated. For example, some sensors are calibrated at the factory and transfer their data digitally back to the acquistion system (e.g. gyro assemblies, some temperature sensors, etc). These require no calibration. In fact, the factory calibration is normally better than what most folks can do on their own.
However, if the sensor passes back an analog signal, there are voltage errors in the network that usually have to be calibrated out. This usually requires finding a standard of some sort (e.g. a voltage reference, a temperature reference) and making sure the acquistion system is calibrated to put out the exact value put out by the reference. This zeros out the bias errors present in the network.
In some cases you don't need to calibrate the acquistion system itself. Simply record the data put out from the acquistion in response to some standard references. You can then fit a curve to the data from the acquistion system. For example, suppose you have a 2.0 V and 3.0 reference. You measure these references with your DAQ. It reads out 2.1 and 3.2 V. If the DAQ is linear, you can create a linear function that converts the output from the DAQ (x) to the calibrated output (y). In this case, the line would be
y -2.0 = (2.0-3.0)/(2.1-3.2)*(x-2.1)
y = 0.909+x*0.909
Plug in 2.1 and you get 2.0.
Some sensors are very nonlinear. Then you may have to measure many points using many references. You then may have to fit a polynomial to the curve. I have seen folks use things like a 7th order polynomial to get a good fit.
any recording device that aquires data must be calibrated!otherwise you don't have a clue where you are or going. these parameters are time,amplitude,etc chk mcgraw hill "waveform analysis"
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