Measurements

The scope measures every capture and lists the results beside the screen (on a phone, under Measurements). A dash means the measurement does not apply, for example a frequency for a flat line.

Measurement	What it is
Frequency	How many cycles a second the signal repeats
Period	The time one cycle takes (1 divided by the frequency)
Peak to peak	Maximum minus minimum
Minimum, Maximum	The lowest and highest voltage in the capture
Mean	The average voltage; for a signal centred on a level, that level
RMS	The root mean square: the steady voltage that would deliver the same power
Duty cycle	The share of each cycle spent above the middle level, for square waves
Sample rate, measured	The rate the board actually used, from its own clock
Spectrum peak	The strongest frequency in the spectrum (when the spectrum is shown)
Spectrum peak level	That peak’s level, in the unit chosen under Spectrum (dBV unless changed)

More measurements

Open More measurements under the main list when you need whole-cycle figures, pulse widths, edge speeds or step levels. It stays closed by default so the screen remains clear, and remembers whether you left it open.

Measurement	What it is
AC RMS	The RMS of the alternating part alone, with the DC mean removed
Cycle RMS	The RMS across whole cycles only, ignoring any partial cycle at the ends of the capture
Cycle mean	The average voltage across whole cycles only
Positive width	The time each cycle spends above the middle level
Negative width	The time each cycle spends below the middle level
Rise time	The time a rising edge takes to climb from 10% to 90% of the step height
Fall time	The time a falling edge takes to drop from 90% to 10% of the step height
Slew rate	How fast the edge changes between the 10% and 90% levels, in volts per second
Top, Base	The settled high and low levels of a pulse or square wave, ignoring brief ringing spikes
Amplitude	Top minus Base (distinct from Peak to peak when the edges ring)
Overshoot	How far Maximum rises above Top, as a percentage of Amplitude
Preshoot	How far Minimum dips below Base, as a percentage of Amplitude

Trust the numbers

• Frequency and period need at least one full cycle on screen; two or more is better. Press Autoset if they show a dash.
• A capture must hold whole cycles for RMS and mean to be exact; with many cycles on screen the difference is small.
• If part of the screen is hatched, a capture is shorter than the screen; a note under the measurements says why and how to fill it (see Rate setting).
• A warning that the signal is faster than half the sample rate comes from the Alias check: the figures above it describe a false, slower wave until you raise the rate.
• Peak to peak and the shape need enough samples in each cycle. With fewer than 10, a note under the measurements says so: the frequency is still right, but raise the rate if you can. See Samples a cycle.
• Readings can only be as accurate as the board’s input. See Accuracy and limits.

Link health

Under the list, Blocks lost counts captures that did not arrive, and Corrupt frames counts ones that arrived damaged and were thrown away. Both should stay at 0; if they climb, see Troubleshooting.