IviScopeWaveformMeasurement Extension Group Overview

LabVIEW IVI Class Driver

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IviScopeWaveformMeasurement Extension Group Overview

The IviScopeWaveformMeasurement extension group defines extensions for oscilloscopes capable of calculating various measurements such as rise-time, fall-time, period, and frequency from an acquired waveform.

Note  In the following table, the literal string IVISCOPE_VAL_ precedes the measurement name.

Waveform Measurement Descriptions

Measurement Name Description
RISE_TIME The length of time for the first rising edge of the signal to rise from the low reference level to the high reference level.
FALL_TIME The length of time for the first falling edge of the signal to fall from the high reference level to the low reference level.
FREQUENCY The frequency of one complete cycle in the waveform.
PERIOD The length of time of one complete cycle in the waveform.
VOLTAGE_RMS The true Root Mean Square voltage of the entire waveform.
VOLTAGE_CYCLE_RMS The true Root Mean Square voltage over the first cycle in the waveform.
VOLTAGE_MAX The maximum amplitude found in the entire waveform.
VOLTAGE_MIN The minimum amplitude found in the entire waveform.
VOLTAGE_PEAK_TO_PEAK The absolute difference between the VOLTAGE_MAX and the VOLTAGE_MIN in volts.
VOLTAGE_HIGH The voltage that corresponds to 100% when using the reference levels. The oscilloscope calculates this value using either the min/max or histogram methods. The min/max method uses the maximum value found. The histogram method uses the most common value found above the middle of the waveform.
VOLTAGE_LOW The voltage that corresponds to 0% when using the reference levels. The oscilloscope calculates this value using either the min/max or histogram methods. The min/max method uses the minimum value found. The histogram method uses the most common value found below the middle of the waveform.
VOLTAGE_AVERAGE The arithmetic average in volts measured over the entire waveform.
VOLTAGE_CYCLE_AVERAGE The arithmetic average in volts over the first cycle in the waveform.
WIDTH_NEG The length of time between the mid reference level points of the first negative pulse in the waveform.
WIDTH_POS The length of time between the mid reference level points of the first positive pulse in the waveform.
DUTY_CYCLE_NEG The ratio of the WIDTH_NEG to the PERIOD of the first cycle in the waveform expressed as a percentage.
DUTY_CYCLE_POS The ratio of the WIDTH_POS width to the PERIOD of the first cycle in the waveform expressed as a percentage.
AMPLITUDE

The VOLTAGE_HIGH less the VOLTAGE_LOW in volts over the entire waveform.

AMPLITUDE = VOLTAGE_HIGH-VOLTAGE_LOW
OVERSHOOT

The relative waveform distortion which follows an edge transition. It is calculated using the following formula:

  • for the rising edge:

    where the local maximum is the maximum voltage of the signal in the first half of the time period that commences when the rising edge crosses the high reference level and concludes when the subsequent falling edge crosses the high reference level.
  • for the falling edge: where the local minimum is the minimum value of the signal measured in the first half of the time period that commences when the falling edge crosses the low reference level and concludes when the subsequent rising edge crosses the low reference level.
The instrument makes the measurement on the edge closest to the beginning of the waveform record. The units are the percentage of the signal amplitude.
PRESHOOT The relative waveform distortion which precedes an edge transition. It is calculated using the following formula:
  • for the rising edge:

    where the local minimum is the minimum value of the signal measured in the second half of the time period that commences when the preceding falling edge crosses the low reference level and concludes when the rising edge crosses the low reference level.
  • for the falling edge:

    where the local maximum is the maximum voltage of the signal in the second half of the time period that commences when the preceding rising edge crosses the high reference level and concludes when the falling edge crosses the high reference level.
The instrument makes the measurement on the edge closest to the beginning of the waveform record. The units are the percentage of the signal amplitude.
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