Oscilloscope Fundamentals
Capturing Your Signal
What is an oscilloscope anyway?
An oscilloscope is a diagnostic instrument that plots the amplitude of an electrical signal as it changes over time. The picture below shows the block diagram of an oscilloscope.
Avoiding Pitfalls
- No Signal:
- Is the channel / device under test turned on?
- Is the waveform off the screen? Try the Autoset feature of adjusting the vertical position / scale.
- Is the instrument waiting for trigger? (Is it displaying “Ready”?) Verify trigger source; try adjusting the trigger level, forcing a trigger or switching to auto mode.
- Aliasing: If the frequency of the signal on the screen seems too low, or it is difficult to get a stable waveform on the screen, adjust horizontal scale to increase the sample rate.
- Unexpected measurement results: Verify that probe is compensated, verify measurement settings such as ref levels and gating, verify the probe attenuation.
- No stable signal: Verify trigger source, trigger level.
| Connect the instrument to circuit | |
| 1. | Connect the probe to the input channel of the instrument. |
| 2. | Check probe compensation: Attach the probe tip to the probe compensation test point on the instrument. Adjust the probe compensation until you see a clean square wave on the screen. |
| 3. | Connect probe ground to the circuit ground and probe tip to the signal you want to view / measure. |
| Set the total amplitude to be displayed on the screen | |
| Scale | Adjusts the size of the waveform on the screen per channel, a larger waveform gives better measurement resolution. |
| Position | Moves the waveform up and down on the screen. |
| Attenuation | Sets the maximum voltage that can be displayed; scope attenuation setting needs to match probe attenuation. |
| Input Coupling | Use DC coupling to see all the input signal. Use AC coupling to see only the AC signal riding on top of a DC offset. |
| Set the total time to be displayed on the screen | |
| Scale | Sets the amount of time displayed on the screen for all channels. |
| Position | Moves the waveform left or right on the screen. |
| Stabilize the waveform on the display | |
| Source | Select which input signal is compared to the trigger settings. |
| Type | Edge trigger is the most commonly used trigger type;trigger on rising, falling or both edges. Other more advanced triggers such as Pulse Width, Runt Timeout, Setup and Hold, Rise/Fall Time, Logic and Pattern trigger types are available for capturing more complex events. |
| Level | Determines the voltage level on the input signal at which the trigger occurs. |
| Measure voltage and time characteristics of signals | |
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04/2023 3GW-60028-2