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Oscilloscope

Oscilloscope

Overview

The Oscilloscope is a measurement tool that displays the waveform of the input signal on a time axis in real-time. It is used to visually confirm the shape, amplitude, and period of a signal. It also includes trigger functions, automatic measurement capabilities, and arithmetic (math) functions.

☕ Coffee Break: An "Ultra-High-Speed Camera" for Electricity

The name "Oscilloscope" might sound intimidating, but what it does is quite simple. Think of it as an "ultra-high-speed camera" that takes continuous shots of how sound or electricity moves.

For example, when you pluck a guitar string, you can see the string vibrating with your own eyes. But once that vibration passes through a microphone and turns into an electrical signal, it becomes invisible to the human eye. Furthermore, sound vibrations happen at breakneck speeds—thousands or even tens of thousands of times a second.

An oscilloscope draws a graph of this rapidly changing electrical voltage over "time," moving from left to right. With this tool, you can clearly see the exact shape of a "plink" sound, or how noise is mixed in, revealing the true form of invisible electricity right before your eyes!

Basic Operation

Starting and Stopping Measurement

  • Start/Stop button: Toggles the measurement start and stop.

Reading the Screen

  • Time/Div: Changes the scale of the time axis (horizontal axis). Larger values display a longer duration (slower changes), while smaller values zoom in to show a shorter duration (faster changes).
    • 💡 Key Point: Even when displaying a long duration, the system continues to record the waveform internally at high resolution. Therefore, you don't have to worry about the waveform becoming 'choppy' or losing its trigger sync.
  • Scale: Changes the scale of the voltage axis (vertical axis).
    • Left Scale / Right Scale: Allows you to set the display magnification for each of the left and right channels. "1.0x" is the standard; setting it to a larger value, such as "2.0x", will vertically expand the display of the waveform.
  • Channels: Check boxes can be used to toggle the display/hide status of each channel (Left/Right).

Trigger Settings

A function to stop (stabilize) the waveform for easier observation.

💡 Why do we need to stop the waveform? Sound and electrical waves repeat the same shape at incredible speeds. If displayed exactly as they are, the waveform would flow left and right so fast that to the human eye, it would just look like a blurry band. The trigger function sets a rule: "Take a picture the exact moment the wave reaches this height (Level)!" By updating the screen at the exact same timing every time, it looks as if the wave has completely stopped. It's the exact same principle as shining a strobe light on a moving object in the dark to make it look like it's standing still!

  • Source: Selects the signal source for the trigger (Left or Right).
  • Slope: Selects the direction in which the signal crosses the trigger level.
    • Rising: Triggers when the voltage increases from low to high (rising edge).
    • Falling: Triggers when the voltage decreases from high to low (falling edge).
  • Mode:
    • Auto: Updates the waveform at regular intervals even if the trigger conditions are not met (something is displayed even if no signal is found).
    • Normal: Updates the waveform only when the trigger conditions are met (the screen stays frozen until a signal arrives).
    • Single: Captures the waveform only once when the trigger conditions are met and then automatically stops (useful for observing one-time signals).
  • Level: Sets the voltage level at which the trigger occurs.

Persistence Settings

A feature to display an "afterimage" similar to an analog oscilloscope. It is useful for visually capturing noise distribution and waveform fluctuations (jitter).

💡 The Sparkler Effect If you wave a sparkler around in the dark, the afterimage of the light lets you draw letters or pictures in the air, right? Persistence is exactly that. By leaving a faint trail of past waveforms on the screen, it becomes much easier to visually spot rare, abnormal noise (a sudden spark) or subtle waveform shaking (jitter) by looking at how the light overlaps over time. Even in the digital age, this 'analog afterimage' is the ultimate weapon for finding noise!

  • Enable Persistence: Enables the persistence display.
  • Decay: Adjusts the time until the afterimage disappears (decay rate). Moving it to the right makes it last longer.
  • Intensity: Adjusts the brightness and density of the afterimage.

Tools and Measurements

Measurements

The current signal measurement values are displayed in the upper left of the screen.

  • Vrms: Root mean square voltage.
  • Vpp: Peak-to-Peak voltage (the difference between maximum and minimum values).

When "Enable Waveform Measurements" is checked, the following additional measurement values are also displayed (automatically calculated from the waveform shape).

  • Freq: Frequency (displayed in Hz, kHz, etc.).
  • Rise/Fall: Rise/Fall time (displayed in s, ms, us, ns).

Cursors

When "Enable Cursors" is checked, two cursors (C1, C2) are displayed on the screen. By dragging these cursors with the mouse, you can measure details such as the time difference (dT), frequency (1/dT), and voltage difference (dV) between two points.

Math Functions

Displays the results of calculations performed on two channels or signals as a "Math" waveform (white dotted line).

  • Off: No calculation.
  • A + B: Left + Right.
  • A - B: Left - Right.
  • A * B: Left × Right (product).
  • A / B: Left / Right (quotient).
  • Derivative: Differentiated waveform of the Left channel.
  • Integral: Integrated waveform of the Left channel.

Filter

Applies a simple filter to the input signal for display. Convenient for checking noise, etc.

  • Type: LPF (Low Pass), HPF (High Pass), BPF (Band Pass).
  • Cutoff / Freq: Sets the cutoff frequency or passband of the filter.