Term
| Analog signal conditioning |
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Definition
| A signal (usually electrical), some component (such as amplitude or frequency) of which is continuously proportional to another variable (temperature, wind speed, etc. in meteorology. |
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| Analog-to-digital converter |
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Definition
| A device which quantizes the information content of an analog signal, that is, transforms it into a finite set of discrete output states, and assigns a digital code to each output state. Essential elements are an analog input signal with a defined input range, a reference quantity, and an output expressed as a finite number of states each representing a discrete input quantum |
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| An instrument used to calibrate other instruments, whose calibration can be traced to national or international standards, and ultimately to primary standards used in the SI system. |
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| Data faults must be detected rapidly, corrective action must be initiated. Questionable data must be flagged |
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| Digital signal processing |
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| After signal is in digital form, it may be manipulated by digital processing elements, most commonly a microprocessor. |
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Definition
| A source of error in instruments caused by physical changes in the instruments subsequent to calibration. For example, leakage of air into an aneroid cell would degrade the vacuum and cause drift. |
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Definition
A way of defining a sensor response to a changing input.
The most widely known dynamic performance parameter is the time constant. |
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Definition
| Due to a changing input, is the sensor output, after static calibration has been applied, minus the input at any given instant. Commonly used with ramp inputs. |
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Definition
| Error due to improper sensor exposure or failure to provide adequate coupling between the sensor and the measurand. |
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| Standard guidelines for the exposure of meteorological instruments. A wind exposure standard may specify distance from the senor to obstacles, slope of the land, and character of vegetation in the vicinity. |
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Definition
| A measurement system, which interacts with the atmosphere and delivers data (information about the desired atmospheric variables) to the users. |
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| In-situ or immersion sensors |
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Definition
Sensors in direct contact with the atmosphere being measured
Ex: thermometer, anemometer, pressure sensors |
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Definition
| An instrument consist of a senor, which interacts with the measurand, and may also include signal conditioning elements, an analog-to-digital converter, data processing elements, data transmission elements, data storage elements, and a mechanism for data display. |
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| Generic term for sensor input(s). Temperature is the measurand of a thermometer. |
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| Reference to a standardized set of performance definitions. These characteristics are used by manufacturers to describe instruments and as purchase specifications by buyers. |
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| The measurand, the desired input as opposed to secondary inputs, which usually are unwelcome. |
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| A procedural standard defines procedures used in data acquisition such as sampling time and averaging time. |
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Monitor the state of the atmosphere at distances great enough to eliminate interaction between the sensor and the parcel of air being sensed.
Ex: radar, lidar, sodar |
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Definition
| Other sensor inputs in addition to the primary input or measurand. Secondary inputs are usually unwanted. Temperature is a secondary input to an aneroid barometer. |
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Definition
| The primary transducer in an instrument. It is the one that interacts with the measurand. |
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Definition
| A fluctuating quantity, typically mechanical (distance, orientation, rotation, rate, etc.) or electrical (voltage, current, frequency, etc.), whose variations convey information about the measurand. The information content may or may not be coded. A voltage proportional to temperature is a signal, as is a sequence or binary bits that represents the digitally coded value of the temperature. |
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Definition
| Those obtained when the senor input and output are static (not changing) |
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Definition
| At any given instant, static error is the observed value (sensor or instrument output) minus the reference value (input as measured with a reference quality instrument) while the input is held constant and while the sensor output is steady. |
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Definition
| Slope of the transfer equation or curve. It is a measure of the sensitivity of a senor in the static sense. Also the derivative of the raw output with respect to the input. |
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Definition
| A device, which converts energy from one form to another. All sensors are transducers. In addition to the senor, transducers are used in an instrument to convert the raw sensor output to a more useful form, often voltage. |
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