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5a_Postlab

# 5a_Postlab - is ±z 90 ·σ n evaluate the uncertainty for...

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ME365 POSTLAB 5A Fall 2011 Compare the sensor calibration listed in Table 1 and answer the questions below. Table 1: Results of Static Calibration Analysis Sensor A Sensor B Sensitivity (K, mV/°C) .1 .07 Bias (b, mV) -0.2 -0.5 Standard Error (σ n , mV) 0.025 0.003 Because of the large amount of data used to generate the calibration curves, the confidence intervals of the sensitivity and bias are quite small, so K and b are reliable. Hysteresis and nonlinearity were not factors for the temperature range of interest. We need to measure temperatures to within 0.25°C. The total range of temperatures we need to measure is 200°C. 1. If we use a 12 bit ADC to acquire the data with a nominal input range of ±0.05 V. What is the input resolution of each sensor in °C, if the output resolution is limited by the quantization interval? 2. The standard error gives us a measure of how far from the true value any data point might lie (usually due to noise on the measurement). If we use the 90% confidence interval for a data point as the uncertainty (i.e. uncertainty

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Unformatted text preview: is ±z 90% ·σ n ), evaluate the uncertainty for each sensor in °C. 3. With the current system, which sensor gives a more precise measurement and will the final uncertainty be less than 0.25°C (Uncertainty from quantization is max rounding error, Q/2, and is independent from Uncertainty from problem 2)? ME365 POSTLAB 5A Fall 2011 4. We are considering upgrading the data acquisition system’s ADC to a 16 bit system, but we would like to know if we can save expense by reducing the input range of the ADC instead. If we reduce the input span to 40 mV, will the error from quantization be less than the uncertainty from the noise (due to σ n ) for both sensors? 5. The temperatures we are measuring are slowly varying (which is why we are only considering the static response), so we can possibly filter/average the sensor signal and minimize the effects of random noise. For our future reference, which sensor would be best if experiments confirm the effects of noise can be made negligible?...
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