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17 Cards in this Set
- Front
- Back
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Difference between analogue and digital signals? |
Continuous and sampled at discrete time intervals |
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Draw the hardware system diagram |
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What is a sensor? |
Device that converts a signal representing a physical property into an electrical signal. |
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What is an ideal sensor? |
No noise Small Low cost Accuracy Efficiency Instantaneous Maintenance free Robust to environment and disturbances |
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What is range and span? |
Range is the limits between input can vary eg can detect between 1-50m. Span would be 49m. Max minus min |
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What is error? |
Difference between the measured result and the true value of the quantity being measured. Error = measured value - true value |
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What is accuracy? |
How close is the data from the target The extent of the measured value being wrong. Eg +- 2deg. Can be given as percentage of full range. |
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What is the difference between accuracy and precision? |
Accuracy is how close you can get to the target. While precision is getting a similar value all the time - low spread of data |
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What is sensitivity? |
Indicating how much output there is per unit input. Can be a percentage. Eg 0.5ohm/deg C or +- 1% of the reading per deg C |
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What is linearity or non linearity error? |
The assumption that sensors have linear output. The error is the difference from the linear line to actual value. 3 ways of calculating error. |
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What is repeatability? |
The ability to give same value given the same input. |
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What is dead band/time? |
Range if input values for which there is no output. |
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What is resolution/ quantisation error? |
Smallest change in the input value that will cause observable change in output value. |
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What is output impedance? |
Resistance sensor has in circuit. It can significantly affect output |
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What is response time? |
The rise time - 0-95% eg |
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What is stability of a sensor? |
Ability to give the same output when it is measuring a constant input. Drift is used to describe change in output over time |
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What is bandwidth? |
Between upper and lower cut off frequencies |
