Warthog Systems LabHelper X
          Y-axis scaling; sample averaging
            using LabHelper

This operation sets the upper and lower Y-axis limits for the screen display of a particular channel.  The default values are -5 to 5.  If you pick one of the pre-defined voltage conversions, the Y-axis scaling will be preset automatically.  Similarly, if you use the 'Direct calibration' function, scaling will be based on the range of values used during the calibration procedure.  If you wish to set a different scaling from the default or the pre-defined values, enter your choices in the two edit fields before you click the 'Selection OK' button.

Note that the scaling you select applies only to the SCREEN display.  Even if values are offscale on the screen, they will still be recorded correctly in the data file -- provided they do not exceed the voltage limits of the A to D hardware.

  • As for other parameters, you can set or adjust the scaling limits in the DISPLAY SETUP window. 

Sample Averaging

These menu options let you select the number of voltage readings to be averaged for each recorded Chart sample value.  Averaging is useful for eliminating background electrical noise, or other short-term variation that may obscure long-term trends.  It may also be used to obtain single integrated readings from long intersample intervals.  Some important aspects of averaging:

  •   When the default Continuous, all channels option is selected (A-D menu; available in Chart mode only), all channels are scanned sequentially and continually throughout the sample interval.  The Averaging window does not appear, and differences in the number of averaged readings between channels are not possible.  This mode provides a more continuous sampling of each channel than in the 'User specified, each channel' mode (A-D menu), wherein each sample is sampled for a specific number of averages before proceeding to the next channel.  It differs from the 'continuous, last channel' option (A-D menu) in that all channels are scanned continuously, not just the last one.

    In Continuous, all channels mode, the number of averaged readings per recorded sample depends on the number of channels, the sample interval, and the speed of the computer and the A-D converter.

    NOTE:  sample averaging is automatic if you have selected Oscilloscope plus Chart mode.  In this mode a voltage reading is made from ALL channels when the oscilloscope reading is made.  When the sample interval for chart channels has elapsed, the stored readings for the chart channels are averaged, plotted, and saved.  Thus the number of samples averaged for chart channels is roughly equal to the value:

    chart sample interval / oscilloscope sample interval

    Use of this method simplifies calculations and allows the highest possible oscilloscope sampling rate.

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