Tektronix H500 User Manual page 77

When using the Internal Timebase trigger with Repeat Interval or Both selected, the instrument trigger time depends on how
the instrument interprets the trigger time in relation to the closest 24-hour point within ±12 hours of the current instrument
time. See the Spectrum Triggering Tips Online help topic for more information on using the Internal Timebase trigger with
the Repeat Interval or Both setting.
A trigger icon, located at the top of the display graticule, is shown when the instrument is in Amplitude vs Time measurement
mode (Time Domain). The trigger icon marks the position of the trigger event on the waveform for all trigger modes except
Free Run.
In Spectrum-based measurements, IF level triggering can occur even when no part of the displayed waveform reaches the
specified trigger threshold level. This happens because trigger level detection is done on the total signal power in the span
bandwidth, while the displayed spectrum waveform shows the signal power divided into RBW intervals across the span. For
modulated signals with bandwidths wider than the RBW setting, the signal spectrum power level in any RBW interval is lower
than the total signal power detected by the trigger system.
Certain settings or combinations of settings can disable External triggering. When triggering is disabled, the instrument displays
a yellow highlighted notification message for a short period and disables the Trigger tab controls. Changing the settings to
those that allow triggering enables the Trigger tab controls. The following are the most common causes of disabled triggering:
Setting Span greater than 20 MHz
Setting any combination of Span and Resolution BW (RBW) that requires multiple signal acquisitions to take a measurement
Selecting DPX, Audio Demod, or Signal Strength measurement modes (including Signal Classification Audio Demod mode)
H500 User Manual
Operating basics
51