The voltage threshold is also known as the Trigger Threshold, Trigger Voltage or Transition voltage. When capturing the activity (voltage changes) on the channels, this is the voltage level that determines the difference between storing a 1 or storing a 0.
For a typical circuit where the lowest voltage indicates a '0' and the highest voltage indicates a '1', you would set this value to the middle of those two voltages (i.e. for 5 Volt CMOS set the threshold to 2.50 volts).
If too much noise activity is being captured, setting this level higher (away from ground bounce or noise) or lower (away from peak bounce or noise) will improve the quality of the capture and even extend the capture time by preventing the storage of phantom transitions or 'garbage'. When decoding serial protocols, capturing noise can cause poor decoding or no decoding at all.
The number of thresholds, the number of channels and the voltage range varies between models. These variations are shown below.
The cable(s) and channels affected by the threshold setting are displayed first. This area also displays the channel numbers, colors and the detected channel activity (relative to each other).
Below the channel indicator area is the current threshold value.
The selection box provides quick selection of standard values to use for common logic families and also indicates the current value in relation to these common settings. The slider bar beneath the selection box can be used to manually set a custom voltage. The mouse can be used to move the slider and once selected by the mouse, the cursor keys can be used for fine adjustment. If the selected voltage does not match a common selection, an indicator will be placed in the selection box between the two closest values.
Threshold adjustments update the hardware immediately.
Threshold settings for Models DV3109, DV3209, DV3409 and Models DV3100, DV3200 (in 9 Channel Mode)
Threshold settings for Models DV3100, DV3200 (in 18 Channel Mode)
Model DV3400 (in 18 Channel Mode)
Model DV3400 (in 36 Channel Mode)
Model DV3500 (in 18 Channel Mode)
Model DV3500 (in 36 Channel Mode)