Measuring Waveforms
3–82
TDS 420A, TDS 430A, TDS 460A & TDS 510A User Manual
Be careful when taking automatic measurements on noisy signals. You might
measure the frequency of the noise and not the desired waveform.
Use High-Low Setup (page 3–78), Reference Levels (page 3–78), and Gated
Measurements (page 3–77) with snapshot exactly as you would when you
display individual measurements from the Select Measrmnt menu.
The oscilloscope provides a graticule for measuring the difference (either in time
or amplitude) between two points on a waveform record. Graticule measure-
ments provide you with quick, visual estimates. For example, you might look at
a waveform amplitude and say, “It is a little more than 100 mV.”
Measure Waveform Amplitude. To measure the amplitude of a waveform, do the
following steps:
1. Press the channel selection button of the channel you wish to measure. Note
the vertical scale factor for the channel in the channel readout on screen.
2. Count the graticule divisions between to two features to be measured and
multiply by the vertical scale factor.
For example, if you count five major vertical graticule divisions between the
minimum and maximum values of a waveform at a scale factor of 100 mV/di-
vision, then you can easily calculate your peak-to-peak voltage as:
5 divisions × 100 mV/division = 500 mV.
NOTE. When you select the NTSC graticule, the volts per division of all selected
channels is set to 143 mV/div (152 mV/div for PAL) where the divisions are those
of the conventional graticule, not the divisions of the video graticules. For
NTSC, the actual grid lines represent 10 IRE, and for PAL the lines are
100 mV apart.
Measure Waveform Time. To measure the time of a waveform, repeat the process
just described, but count the horizontal divisions and multiply by the horizontal
scale factor. For example, if you count five major horizontal graticule divisions
for one waveform cycle at a horizontal scale factor of 50 ms/division, then you
can easily calculate the waveform period as:
5 divisions × 50 ms/division = 250 ms, or 400 kHz.
Taking Graticule
Measurements
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