Segmented Capture (Pulse)
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Specifies if the signal acquisition, pulse detection and analysis are performed over a single continuous time acquisition or instead over multiple time acquisition segments.
When Segmented Capture mode is enabled, the Acquisition Length (s), Extra Acquisition (samples) and Include Extra Data Before and After properties are all grayed-out (unavailable) since user should specify desired Segmented Capture mode acquisition length using the separate Segment Length (s) and Segment Count properties.
Segmented Capture mode can also be enabled in the Input > Capture tab.
When Segmented Capture mode is enabled:
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Segment Type: Specifies the total number of consecutively triggered acquisition time segments, over which the pulse detection and analysis will be performed.
Segment Type can also be set in the Input > Capture tab.
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Fixed: Segmented capture acquires a fixed amount of data. Capture starts when the signal crosses the defined trigger threshold, and stops after a fixed amount of data is acquired (based upon the current VSA measurement setup). Segments continue to be acquired until the specified segment count is reached. See Fixed Length Segmented Capture for more information.
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Variable: Variable length segmented capture uses gated acquisition to control the start and stop of each segment based on gating criteria. For example, you can use IF Magnitude triggering to start capturing data when the rising edge of a pulse crosses the IF Magnitude threshold, and to stop capturing on the falling edge of the pulse. You can capture additional data before and after the pulse using the Gate Start Delay and Gate Stop Delay parameters. This method of segmented capture removes long stretches of undesired "off" time from the acquisition, which can dramatically reduce memory usage. See Variable Length Segmented Capture for more information.
If you are having difficulty achieving pulse detection for variable length segmented capture, try increasing the FM Filter Bandwidth. A larger filter bandwidth reduces the amount of settling for the low-pass FM Frequency Modulation Filter.
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Capture Length Type: Selects the measure used to set the length of the capture sequence.
Capture Length Type can also be set in the Input > Capture tab.
- Count: Segmented capture occurs for the number of segments specified by Segment Count (Fixed Segment Type) or Desired Segment Count (Variable Segment Type).
- Duration: Segmented capture occurs for the length of time specified by Desired Capture Duration. This selection is only available in Playback mode (Input > Data From > Recording).
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Segment Length (Segment Type = Fixed): Specifies the per segment acquisition length in seconds. In other words, how much data to analyze in each segment. The analyzer acquires additional data in each segment to account for settling of various digital filters, including the low-pass FM Filter used during pulse analysis. This is handled automatically by the analyzer.
When playing back a segmented capture recording, the length of the segments in the recording places a maximum limit on the Segment Length that you can analyzer. Filter settling directly reduces the amount of data that is available for analysis of each segment. If you are unable to set the Segment Length long enough for your desired measurement, try increasing the FM Filter Bandwidth – a larger filter bandwidth reduces the amount of settling for the low-pass FM Filter.
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Segment Count (Segment Type = Fixed): Specifies the total number of consecutively triggered acquisition time segments, over which the pulse detection and analysis will be performed.
Segment Count can also be set in the Input > Capture tab.
has priority over . Setting Segment Count will not affect , but setting will reduce if necessary to achieve the set .
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Desired Segment Count (Segment Type = Variable): Sets the desired number of segments to be captured. With segments of varying length, it may be difficult to know for sure if the number of segments you want to capture will occur in the acquisition. As many segments as possible will be captured up to the specified number.
Desired Segment Count can also be set in the Input > Capture tab.
has priority over . Setting Segment Count will not affect , but setting will reduce if necessary to achieve the set .
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Desired Capture Duration (Segment Type = Variable): Sets the desired length of time (in seconds) for the capture. With segments of varying length, it may be difficult to know for sure how many segments will occur in the desired capture duration. As many segments as possible will be captured within the desired capture duration.
Desired Capture Duration can also be set in the Input > Capture tab.
The input acquisition segment identifier associated with each detected pulse is reported as the Segment metric within the Pulse Table results.
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Default checkbox: Off
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Default value (Segment Count) 10
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Default value (Segment Length) 10 us
See Also
