Operating instructions

University of Saskatchewan
Electrical Engineering Laboratory Equipment Manual
At slow sweep speeds, the sampling rate decreases due to an increase in acquisition time.
Sampling is faster then what is required to fill the memory. Push the Main / Delayed key to
display the sampling rate.
Display key > Infinite Persist. The display is updated with new acquisitions and old
acquisitions are displayed in gray. Persistence is limited to the display area and not memory. The
Intensity knob allows a view of old acquisitions. This is useful in viewing glitches. The
Intensity knob has no effect on digital channels.
Acquire key > Realtime. Default setting. The display waveform is from the current
acquisition only. Not available in Average Acquire mode. When less then 1000 samples are
available to display, a reconstruction filter is used to fill in the display.
Trigger
Normal Mode > Only Triggers when conditions are met ( transition or/and a logic level).
Auto Mode > Triggers when conditions are met or forces a trigger when conditions
are not met.
In Auto or Normal mode, a trigger will not be recognized until the pre-trigger buffer is full. At
slow sweep speeds (ms/div), the trigger may not be found. Use Normal mode and wait for the
trigger indicator to flash before causing the trigger condition in the circuit.
HF Reject is a 50 kHz input low pass filter to the trigger circuit. Noise Rej increases the
trigger hysteresis band, thus reducing noise triggering. This also reduces trigger sensitivity. The
signal may have to be increased.
Holdoff keeps a trigger from occurring until the amount of time set has passed since the
last trigger. Used, on a repeating pattern of a waveform, to trigger on the same edge of the
pattern.
Edge triggers on a falling or rising transition. Pulse Width triggers after a time set pulse
width has occurred. Pattern trigger is a logical AND of the channels. Channels can be specified
high, low, or don’t care (X). A rising or falling edge can be set for only one channel. A trigger
will occur when the specified conditions for all the channels is true. There are many types of
triggers, for specialized waveforms, in the More hard key category. Consult the User’s manual,
available from the technicians, for the many types of triggers.