Cursors, reference, trend and saving

Cursors

Two lines, A and B, to measure between two points on the time view. Drag them on the screen, or use their step keys, which appear in the controls while cursors are on. Keyboard: C.

Choose Cursor type in the cursor controls:

• Time places two vertical lines (Cursor A and Cursor B) across the trace. The readout gives each cursor’s time and voltage on the signal, the time between them (Δt, B minus A), the frequency that time implies (1 / |Δt|), and the voltage difference (ΔV, B minus A).
• Volts places two horizontal lines (Level A and Level B) across the trace to measure amplitudes, thresholds or DC levels directly. The readout gives Level A, Level B and ΔV, B minus A.

Reference

Keeps the capture on screen as a dashed trace, to compare against later ones, for example before and after changing a component. Its frequency and peak to peak are shown under the screen. New reference replaces it; Clear ref removes it. Keyboard: R.

When a spectrum is present, Reference keeps that too, including an average or hold. The dashed spectrum follows the current frequency and level axes; its stored values do not change when you change the window or trace mode. Turn on Markers for each marker’s live level minus the reference level. Differences are in dB for decibel units, or volts RMS for V. The reference uses its nearest stored frequency, shown alongside the difference. Outside its captured frequency range the difference is unavailable. Different windows or frequency steps can change the readings, so use matching settings for a controlled comparison. A time-only capture has no reference spectrum.

The reference lasts until you clear it, replace it or reload the page.

Mask test

While a reference trace is on screen, a Mask test group appears in the key panel. Turn Mask test On to draw a shaded corridor around the reference waveform and check every live capture against it:

• Tolerance sets how wide the allowed corridor is in both time and voltage: 0.2 div, 0.5 div or 1 div around the reference trace.
• Stop on fail automatically stops the scope as soon as a capture steps outside the corridor, so you can leave the scope running to catch an intermittent glitch and inspect the offending capture on screen.
• Reset count zeroes the Pass and Fail capture counters.

Trend

Opens a window that charts one measurement over time while the scope runs: frequency, period, voltage figures, pulse widths, edge times, levels and, while the spectrum’s Distortion figures are on, THD, SNR, SINAD, SFDR or ENOB. It gives the number of readings, how long it has been logging, and the minimum, mean, maximum and standard deviation. Open All logged measurements under the chart to compare those statistics across every quantity at once, or click any row to chart it. Use it to watch a drift, a battery running down, or a temperature effect. It can save its log as CSV.

Saving

• Save CSV saves the capture on screen as a spreadsheet: each sample’s time and voltage, with the settings it was taken with.
• Save spectrum CSV appears while a spectrum is available. It saves every frequency step and its level in the chosen unit, including the displayed average or hold. Zoom does not crop the exported data. The header records the window, trace mode, capture count, resolution bandwidth and whether the spectrum uses the time cursors. V means volts RMS; dBm assumes 50 ohms.
• Save PNG saves a picture of the screen, with a caption of the settings and measurements. The spectrum and dashed reference are included when shown, with spectrum settings in the caption.
• Copy report copies the measurements and settings as a table, ready to paste into a lab report or a document. With More measurements, the cursors or the distortion figures open, it includes them too. With the peak table on, it also includes the peaks, their levels in the chosen unit and their relative levels in dBc.