If an oscilloscope is to be used to acquire and analyze an input signal, three basic settings must be made on the device: vertical, horizontal and triggers. If you know the function of these controls, you can use the oscilloscope for your specific measurement needs.
Vertical system and controls
The vertical controls allow the signal to be vertically positioned and scaled, as well as to adjust the input coupling and other signal states. These include:
- Position and Volts per Scale: Allows you to position and scale the signal exactly where you want it on the screen.
- Input coupling: Can be set to DC, AC or ground. For DC coupling, all parts of the input signal are displayed. In AC coupling, the DC component of the signal is suppressed and the signal is centered at the vertical ground reference.
- Bandwidth Limiting: Limiting bandwidth reduces unwanted noise that sometimes occurs in the signal presented. The result is a sharper signal representation (although this also reduces the high-frequency signal component).
- Bandwidth Magnification: Some oscilloscopes are equipped with a DSP equalization filter. This filter can be used to increase bandwidth, linearize the frequency response of the oscilloscope, and improve phase linearity.
Horizontal system and controls
The horizontal system of an oscilloscope includes the following important controls:
- Position and acquisition time per scale section
The different acquisition modes
There are several detection modes. These include: The acquisition modes are used to calculate and display the signal points starting from the sampling points. Sample points are the digital values derived directly from the analog-to-digital converter (ADC). The sampling interval refers to the time duration between the sampling points. Signal points are the digital values that are in memory and are used to display the signal on the screen.
- Peak mode
- Average mode
- Hi-Res mode
- Envelope mode
- Signal database mode
A big advantage of digital oscilloscopes is the ability to store signals for later viewing. For this purpose, one or more keys are provided on the control panel, with which the detection system can be started and stopped, so that the signals can be analyzed without time pressure. Oscilloscope users always want to buy the best oscilloscope.
The sampling of the measuring signals
Sampling is the same as taking snapshots. Each snapshot corresponds to a specific point in the signal. Digital oscilloscopes offer several sampling methods:
- Real-time Sampling: The oscilloscope captures enough signal points in a capture sweep to capture and reconstruct an accurate image of the signal.
- Equivalent Time Sampling: Can be used to accurately acquire signals whose frequency exceeds half the sampling rate of the oscilloscope. In equivalent-time sampling, the input signal must be repetitive.
Position and acquisition time per scale section
The horizontal position control allows you to move the signal to the left and right to the exact location on the screen. Timebase settings allow you to set the speed at which the signal is written to the screen (also called the bounce rate).
Other horizontal controls
Depending on the make and model, an oscilloscope may have additional horizontal controls:
- Zoom / Move: Use the controls to set the zoom factor and zoom scale, and move the zoom box over the signal to show a magnified portion of the signal on the screen.
- Find and Select: Enables fast navigation through the search for custom events for long acquisitions.
- XY mode: Allows users to present an input signal on the horizontal axis instead of the time base. This allows various methods of phase measurements.
- Z-Axis: The Z or intensity axis on a Digital Phosphor Oscilloscope (DPO) provides real-time three-dimensional representation, much like an analog oscilloscope. This makes it easier to distinguish the base signal from an occasional transient signal.