AEMC Instruments Oscilloscopes

AEMC Instruments Oscilloscopes

An Oscilloscope is an instrument that is used as a graph displaying device of an electrical signal. The graph will show how signals change over time. The vertical (Y) axis represents voltage and the horizontal (X) axis represents time. The horizontal sweeps at a constant rate. The (Z) axis, although not that common, can display brightness or intensity of the display. With a proper transducer, an oscilloscope can measure just about anything. A transducer is a device that creates an electrical signal in response to physical stimuli such as sound, pressure, light, heat, etc.
 

When graphing a signal, what do you want to find out?

• The time and voltage value of a signal
• The frequency of an oscillating signal
• How much of a signal is direct current (DC) or alternating current (AC)
• How much of the signal is noise and if the noise is changing over time
• To see the “moving parts” of a circuit represented by the signal
• To tell if a malfunctioning component is distracting the signal

Oscilloscopes come in many different versions

• Analog
• Digital
• Mixed signal
• Portable
• PC based versions

If the recording of a waveform is required, a digital scope will be applicable. If you need to see the waveform in real time, or to see the original intensity an analog scope would better suit that requirement.  The higher the input signal frequency is, the higher  the bandwidth that will be required. If you do not have the appropriate amount of bandwidth, you risk the possibility of not getting accurate results.

If there is doubt about the amount of bandwidth that is required, then you should go the next step up. The bandwidth can usually be calculated by this formula: BANDWIDTH = (0.35 / rise time of the signal)

The higher the sampling rate, the more accurate and precise the captured waveform is. As the sampling rate increases, it allows for more samples a captured waveform has, for any given period of time.

In almost every electric application, including lab use, research and development, and product development there is a need for an oscilloscope to provide waveform analysis.

Here is the best guide we can recommend on getting to know everything about oscilloscopes.  This is the XYZs of oscilloscopes by Tektronix.  It has 64 pages packed with information.  Click the picture below to download.

Analog Oscilloscopes

An Analog Oscilloscope will draw waveforms on its display by deflecting an electron beam that sweeps across its screen horizontally. The beam is vertically deflected in proportion to the applied voltage, which allows the shape to reproduce the shape of the target trace. Analog equipment works with continuous variable voltages. Analog oscilloscopes can display signals as they happen.

The immediate representation of a waveform on the CRT (panel) display results in a faster update rate. The CRT’s have a higher resolution and faster waveform update rate. The analog oscilloscope displays the signal in real-time with less risk of modifying any part of the original signal. The original intensity of the waveform can be observed with the CRT. Depending upon application, the intensity of the waveform can be critical.

Analog oscilloscopes are sometimes preferred by some users. They can both interpolate and aliasing the points between the waveforms. Although the analog oscilloscopes do not allow for digital storage and analysis, pre or post triggering information, and high frequency limitations, they can still be used.

The basic difference between the digital and analog oscilloscopes is the display signals. The digital scope can display signals that may happen only once and analog scopes can display signals as they happen, or in real-time.

To use an analog oscilloscope, there are three basic settings to adjust an incoming signal

• Time base: Set the amount of time per division represented on the screen.
• Triggering: Use a trigger level to stabilize a repeating signal, or trigger one event.
• Attenuation: Adjust the amplitude of the signal before it is applied.

What is trace storage?

Trace storage allows for direct-view storage CRT’s. It will display a trace pattern that would normally disappear in seconds to stay on the screen for several minutes.

PC Based Oscilloscopes

PC based oscilloscopes are the modern alternative to the traditional bench top oscilloscope. All data and configurations measured on these scopes can be saved into a PC for further data analysis.

One of the key factors involved is the USB connection. The USB (universal serial bus) is intended for communications between interfaces, such as the oscilloscope and the PC in this instance

PC based scopes come in either internal or external versions. The external version is a small unit that connects to a PC, usually by a USB. They can be used by a laptop or a desktop computer. The internal versions usually come with a plug in card that is PCI format. This does not allow for portability and being that the card is placed in the actual PC, there is a lot of noise which could interfere with the results that are attempting to be measured.

Advantages  of PC Based Oscilloscopes

• Easy to Use
• Portable
• Cost Effective
• Large Display
• Uses already “off-the-shelf” equipment- USB and PC

Portable Oscilloscopes

Portable oscilloscopes are otherwise known as handheld oscilloscopes. They are typically used for on-site contractor maintenance and either in the industrial or electronic field.