Equipment Manual

Siglent SDS1000CML Oscilloscope (PDF)

Equipment Videos

Important Notes

Triggering

Be sure the oscilloscope is appropriately triggered. If not, the waveforms will appear to dance around the screen. Refer to the oscilloscope triggering video for more information.

Scale

When directly comparing two signals, be sure the scales are equal. Rotate the large knobs on each channel to change the vertical (voltage) scale. The scale values are displayed in the lower left corner of the oscilloscope.

The image below shows two signals displayed with different scales. Channel 1 (yellow) has 2 V/division. Channel 2 (magenta) has 500 mV/division. While it appears from looking at the screen that channel 2 has a larger amplitude, that’s not the case. Channel 1 has an amplitude of 4 V (2 V/division * divisions). Channel 2 has an amplitude of 1.5 V (500 mV/division * 3 divisions).

Screenshot of oscilloscope with two different voltage scales. Both channels are sinusoids with equal periods. Channel 1 (yellow) has an amplitude of 2 divisions. Channel 2 (magenta) has an amplitude of 3 divisions. The channel 1 scale is 2.00V/div. The channel 2 scale is 500mV/div.

Position

To correctly measure signal properties, be sure the signals are positioned without an offset from the oscilloscope. Press the small knobs on each channel to zero the position.

Zooming

When measuring timing parameters, be sure the signal is not zoomed out too much. The oscilloscope uses the number of pixels to measure time and voltage values. When zoomed out too much, these measurements will not be accurate.

The figure below shows a signal that is likely zoomed out too much. The signal on channel 2 corresponds to a homogeneous 1st order circuit transient response. The time constant should be ~490 us. However, the measurement shows a time constant of 600 us.

Oscilloscope screen. Channel 1 = square wave. The time scale is zoomed out such that there are four periods displayed on the scope. Channel 2 = 1st order RC transient response. A falling edge is analyzed at t=0 seconds.

The figure below shows the same signal that’s zoomed in to a more appropriate degree. Now the time constant is measured at 520 us.

Oscilloscope screen. Channel 1 = square wave. The time scale is zoomed in such that there is one period displayed on the scope. Channel 2 = 1st order RC transient response. A falling edge is analyzed at t=0 seconds.

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