Trigger

Without a trigger, each capture starts at a random point in the wave and the trace jumps about. The trigger finds the moment the signal meets a chosen condition, and lines every capture up at that point.

Mode

• Auto shows every capture, lined up when the trigger is found, and still shows the signal when it is not (for example a flat line). The usual choice.
• Normal shows a capture only when the trigger is found, and otherwise keeps the last one on screen. Use it for signals that only sometimes cross the level.

Is it triggered?

The strip above the screen says how the latest capture went:

• Triggered: the trigger event was found, and the trace is lined up on it.
• Not triggered (Auto): no event in this capture, so it is shown as it came, and moves.
• Waiting for a trigger (Normal): no event yet; the screen keeps the last capture that had one.

If the event was found only early in a capture, the trace is still lined up on it, and the part of the screen before the capture starts is hatched.

Edge

• Rising triggers when the signal goes up through the level (or starts a positive pulse or high timeout).
• Falling triggers when it goes down through the level (or starts a negative pulse or low timeout).
• Either triggers on the first rising or falling crossing in either direction.

Trigger level

The voltage the signal must cross. Each press moves it a tenth of a division; you can also drag the marker at the right edge of the screen. If the trace will not hold still, the level is probably above or below the whole signal: press Autoset, or move the level into the middle of the wave.

More trigger

Open More trigger below the level control to choose a specialised Trigger type or enable trigger conditioning:

• Edge: the standard trigger on a rising, falling, or either-direction crossing of the level.
• Pulse width: catches pulses whose duration across the level is Shorter or Longer than the chosen Pulse width (useful for catching narrow glitches or missing pulses). The trace aligns on the closing edge of the pulse.
• Window: defines a voltage band of height Window span centred on the trigger level, and triggers when the signal Leaves or Enters that band.
• Timeout: triggers when the signal crosses the level and stays there for at least the chosen Timeout without crossing back.
• Noise reject: widens the trigger hysteresis band three times so noisy slow edges do not re-trigger.
• HF reject: applies a low-pass smoothing filter on the trigger path so brief high-frequency spikes do not cause false triggers, without altering the displayed waveform or measurements.