Free Run: In this mode, a new sweep is started immediately upon completion of an old sweep. No trigger event is required to initiate a sweep.
External(TTL): This mode is used in zero span. A TTL signal applied to the External Trigger BNC input connector causes a single sweep to occur. Triggering occurs on the rising edge of the signal. After the sweep is complete, the resultant trace is displayed until the next trigger signal arrives.
Video: This mode is used in zero span to set the power level at which a sweep is initiated. The power level can be set from
–130 dBm to +30 dBm, using the rotary knob, arrow keys, or keypad. The trigger is based on the measured signal level. If no signal reaches or exceeds the trigger level, there will be no trace
on the screen.
Back: Returns to the Triggering Menu.
Used when External or Video buttons are activated. Measurement begins after set time delay once the trigger has occurred. The delay can be entered either as a percentage of the sweep time or as an absolute time delay with units of ns,
μs or ms.
When used, value unit is in dB. Hysteresis can be used with Level and Slope when setting a measurement trigger. Hysteresis is used to prevent undesired triggering when the signal is hovering near the trigger value. For example, the Level is set to 10 dBm, the Slope is set to Rising, and Hysteresis is 1 dB. The first trigger occurs when the signal at least reaches the 10 dBm level. To trigger again, the signal must drop below 9 dBm before returning to 10 dBm. For another example, with Level set to 10 dBm and slope set to Falling, and Hysteresis set to 1 dB, the opposite must occur to activate a trigger. The signal amplitude falls and a trigger occurs when the signal reaches the 10 dBm level. The signal must then reach at least 11 dBm before falling to 10 dBm and initiating a trigger.
