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Keysight Oscilloscope Glossary

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A

AC Waveform

AC stands for "alternating current". Alternating current is generally symmetrical to the centerline (zero). The signal will go positive, stay positive for a little bit, then go negative, stay negative for a little bit, and constantly repeat.

Acquisition Mode

This specifies whether your oscilloscope is currently using "auto2 or "normal" mode. In "auto" mode, the oscilloscope will automatically switch itself into the correct mode. "Normal" mode allows you to switch into all of the different modes yourself, which enables you to take a more active role in how your measurements progress.

Active Probes

This specifies whether your oscilloscope's probes are active or passive. Active probes require an external power supply, but they're extremely sensitive for measuring very high-frequency signals and very low voltages. Passive probes do not require their own power supply, so you can switch them on or off quickly, depending on what kind of measurements you need to perform, but they're not as sensitive and they require an amplifier to boost low frequencies.

Alternate Mode

This specifies whether your oscilloscope is currently in the "alternative trigger" mode or "normal" mode. In normal mode, any triggers that appear on the screen will stay there for as long as necessary. However, if you want to measure a specific time between trigger events, this mode will allow you to do that. It makes it easy to find the maximum or minimum values of your signal.

Amplitude

Specifies whether your oscilloscope is currently displaying amplitude (i.e. voltage) measurements or phase measurements.

Amplitude Modulation

Amplitude modulation means that the voltage of a signal varies with time, and can be shown in an oscilloscope by drawing a line that varies in width or shape over time.

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Amplitude Over Time

Specifies whether your oscilloscope currently displays amplitude (i.e., voltage) measurements over time or phase measurements over time.

Analog Channels

Specifies whether your oscilloscope is currently using the analog channels or digital channels to display measurements. Analog channels give you access to the last part of the signal chain with lower input impedance, and these can be useful for measuring signals where signal loss isn't a big issue.

Analog Oscilloscope

Analog oscilloscopes give you access to the last part of the signal chain with lower input impedance. These can be useful for measuring signals where signal loss isn't a big issue.

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Analog Oscilloscope Cathode-ray Tube

In contrast to digital oscilloscopes that use flat-panel displays, analog oscilloscopes use cathode-ray tubes to display information. Because they can vibrate back and forth, these screens give you a continuous line showing the history of your signal, making it easier for you to see wiggles or high frequencies that might be hard to spot otherwise.

Analog Signal

An analog signal is a continuous waveform. It's called an analog signal because it can take on any value. You’ll see smooth transitions between values instead of the distinct steps produced by digital signals.

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Analog-to-digital Converter (ADC)

Converting an analog signal into a digital one is called "digitizing", This mode lets you choose the rate at which your scope does so. Digitizing too slowly can result in jittery results, but digitizing too fast makes it harder for you to accurately see low frequencies.

Aperture Delay (APD)

APD is also known as "aperture jitter". It is the time error between when the rising edge of an internal clock attempts to open the comparator aperture and when that aperture actually opens. APD can be caused by variations in transistor delays, variations in the voltage reference setting, or power supply fluctuations.

Application

This is the circuit that your oscilloscope is measuring. There are two main types of applications – timing applications and video applications.

ARB Info

Specifies whether your oscilloscope is currently displaying the results of an ARB’s calculation or not.

Arbitrary Waveform Mode

Specifies whether your oscilloscope is currently using "arbitrary waveform mode" or "normal mode". In arbitrary waveform mode, you can generate test signals of any kind and these are quite useful when you're debugging circuits because it enables you to look at things like high frequency noise signals.

Asynchronous Sample Mode

When you enable the "asynchronous sample mode", the oscilloscope will automatically display only one channel at a time. It ensures you don't miss any important signal activity on either of the two channels in the dual-channel instruments.

Asynchronous Signals

To prevent any part of a circuit from affecting other circuits, engineers often use asynchronous signals, meaning the samples received by your oscilloscope will be different at different times. This can be useful to give you an idea about what's happening in a circuit without having any outside influence affect your results.

Attenuated Probes

Attenuated probes use resistors to reduce voltage values before sending them through your oscilloscope's input. They're useful when you need to work with very high voltages because they let you see signals without letting outside interference affect your measurements.

Autoset

Autoset makes it easy to acquire accurate measurements by automatically selecting the most appropriate parameters for each measurement, leading to more consistent results with less user input required.

Auto Measurements

If you want to quickly and easily take all kinds of different measurements, this mode will let you do precisely that, making it easy to find the maximum or minimum values of your signal.

Auto Scale

Autoscaling lets you take many different measurements without manually adjusting the vertical scale to accommodate them.

Auto Setup

In "Auto Setup mode", the oscilloscope automatically adjusts its trigger settings for you to allow a quick look at your signal. This mode is beneficial if you are viewing signals with similar frequencies and amplitude.

Attenuation

Attenuation means that a signal decreases in magnitude or power.

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Auxiliary Input/output

Input/output on most oscilloscopes are used to hook up all of your equipment. Depending on how many inputs the scope has available, you’ll have one or two sets of input/output ports available. Some models also include auxiliary I/O for additional control signals or easier access.

Auxiliary Trigger

The auxiliary trigger lets you trigger your oscilloscope automatically by using an external signal.

Averaging

Averaging refers to a mode on some oscilloscopes that allows you to remove noise from your results. It's more common on high-end models, and it works by taking repeated readings, showing you the average of those readings as one result.

Average Mode (AVG)

When your oscilloscope is in "average" mode, it will average together a certain number of samples and display that averaged result as one sample.

B

Bandwidth

Bandwidth refers to the range of frequencies your oscilloscope can handle. It also determines how many signals you can see at any one time. If the bandwidth is too narrow, then you may not be able to see lower frequencies.

Bandwidth Limits

Oscilloscopes will often have bandwidth limits where they can't measure signals that are too high or too low. If the oscilloscope has a bandwidth limit, then it's usually included in the spec sheet.

Biphasic

This is another word for "two-phased". It often implies that there are two different polarities of the waveform. For example, bipolar signals have two different polarities. Positive and negative signals have different polarities, but they both have the same polarity.

Bipolar Probe

A bipolar probe lets you measure both positive and negative voltages of a signal, while a unipolar probe only allows you to measure positive voltages.

Bits (B)

Are a measurement of analog-to-digital conversion precision. A signal with eight bits of resolution will have one of 28 or 256 possible amplitude values when it is digitized. A signal with ten bits of resolution will have 210 or 1024 possible amplitude values when it is digitized.

Bit Error Rate (BER) or Bit Error Frequency (BEF) or Bit-Error Ratio (BERR)

Bit error ratio tells you the number of errors in a digital data stream per given amount of time, usually one second. In other words, the bit error ratio is the percentage of bits that have been corrupted or misinterpreted in a given time period.

Bit Error Rate Tester (BERT)

A "BERT" is a device that sends test patterns to another device at known bit rates and checks whether there are any errors in the received bits. BERTs are critical components in manufacturing test systems for high-volume products, such as cell phones and hard drives, where a single bit error can lead to a significant cost.

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Bits Per Second (BPS)

The BPS setting tells you how many bits of data will be sent per second at the given clock rate. For example, a 2Gb/s signal will have 1000Mb/s of bandwidth.

Bridge Circuit

A bridge circuit is a four-point measurement device. It has two voltage inputs and two corresponding ground connections.

Budget Oscilloscope

A budget oscilloscope is between one-quarter and one-half the price of a mid-range oscilloscope, usually with fewer features. They are not recommended for engineering use but are suitable for someone who just needs to monitor signals now and again.

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Burst Mode

When your oscilloscope is in burst mode, it will automatically take measurements over a certain amount of time at set intervals. For example, if you wanted to have one measurement per second for ten seconds, you would use burst mode with an interval of 1s and a total measurement time of 10s.

C

Calibration Error

Calibration error is the error in your measurements because of how you use your device or environmental factors that affect your ability to measure signals accurately.

Capture Rate

Capture rate refers to how many points your oscilloscope captures per second. The faster the capture rate, the easier it is to see a signal and determine its shape or characteristics.

Cathode-ray Oscilloscope

A cathode-ray oscilloscope uses a cathode ray tube to display the results of your measurements. A beam of electrons is passed through a series of electrodes, and this creates a glowing dot on the screen that varies depending on the voltage being measured.

Chemical Phosphor Oscilloscope

Chemical phosphor oscilloscopes use a chemical compound to light up and display the results of your measurements. The scope draws a beam of electrons toward this phosphor, and the amount of current determines how brightly it will glow.

Chop Mode

Chop mode lets you use your oscilloscope to measure very high frequencies. It works by chopping the display on and off very quickly, averaging the results of each measurement over time.

Circuit Loading

Different probes can load a circuit differently, which is why it's important to know the specifications of the probe you're using. A high-input impedance probe won't affect the circuit very much, while a low-input impedance probe will likely interfere with the measurements or distort them.

Circuit Specialist

A circuit specialist is someone who knows how to test circuits, but not necessarily how they work or what the measurements mean. They are commonly used to test things like oscilloscopes, multimeters, and other measurement equipment to ensure that everything works as intended.

Common Trigger Modes

Common trigger modes for oscilloscopes include normal, auto, and single. "Normal" triggers when the signal crosses below or above a set point, depending on whether you're using an AC or DC trace. "Auto" lets the scope automatically figure out the voltage and then start measuring once it reaches that level. "Single" allows you to choose precisely when and where you want the scope to trigger and start measuring.

Common Waveform Shape Terms

Many terms describe the shape of a waveform. These include sine, square, sawtooth, triangle shapes, and parabolic and exponential waves. Understanding what these look like is important because it will help you understand your measurements more thoroughly.

Complementary Metal Oxide Semiconductor

CMOS is a low-power digital chip that can operate at very high speeds without overheating or breaking down. They use much less power than other types of chips, and they're ideal for low-power applications like mobile phones.

Complex Waveforms

A complex waveform is a signal that changes over time. An example would be data from an accelerometer or other device that varies with time, such as sound waves.

Composite Video Signal

A composite video signal is a signal that combines both a color and a brightness value into a single waveform. TV sets commonly use it to display on-screen signals from devices like VCRs, satellite receivers, and more.

Constant Rate of Decay

Constant rate of decay is a type of trigger mode that looks for a steady decrease in voltage. It's suitable for measuring digital signals because it only looks at the slope of the signal, not any other factors.

Constant Rate of Rise

A constant rate of rise is a type of trigger mode that looks for a steady increase in voltage. It's suitable for measuring digital signals because it only looks at the slope of the signal, not any other factors.

Conventional Current

Conventional current flows from positive to negative, which is against the direction of electron flow. Electron flow sometimes is also known as conventional current because that was the original convention used when it was discovered.

Control Channels

Control channels are used in data transmission with computers to transfer information from one device to another. For example, when you send a file from your computer to a printer, the print command is considered a control channel because it tells the printer what operations need to be performed.

Coordinate Frame

A coordinate frame refers to a specific location in space that has its own set of axes. For example, you could have a coordinate frame for the XY plane of paper or the XYZ axis system used in science.

Coupling

Coupling is a setting on oscilloscopes that allows you to connect the ground of one scope to another. This is used for bi-directional measurements to transmit signals from one device to another and display on the same waveform.

Coupling Capacitor

A coupling capacitor is an electronic component used in oscilloscopes to reduce other signals’ effect on the one you're trying to measure. It's typically installed right in front of the probe, just before it meets the input port on the device under test (DUT).

Correctable Range

The maximum voltage difference that can be measured on an oscilloscope before noise begins to affect measurements. The greater the bandwidth, the higher the correctable range will be.

Correlated Double Sampling

A technique used to reduce noise in measurements by creating a digital value from an analog value, discarding it, and then measuring the difference between the two. This reduces the effects of noise on the waveform you're seeing.

Crest Factor

A crest factor is a ratio that represents how much larger an AC waveform's peaks and troughs are compared to its RMS value. The greater the crest factor, the greater amount of energy or power involved in the signal.

Cross Triggering

With cross triggering, the trigger signal for one channel allows you to see the result of another channel at that moment in time. This is often combined with delayed sweep so that you can get an idea about how one signal affects another over time.

Current Probes

Current probes are used to measure the amount of current in a system. They have very low impedance, so they don't affect the device being tested. Some current probes also come with switches you can use to select between high and low impedance modes, suitable for measuring different components.

Cursor Measurements

Cursor measurements measure the voltage at a specific point on an oscilloscope display. Many modern scopes feature cursors that can be automatically or manually positioned to measure rising edges, falling edges, and other important points in signals.

Cutoff Frequency

The cutoff frequency is the lowest point in a band-pass filter filter's transition point to blocking frequencies. It's where all frequencies below the cutoff frequency are allowed. The higher the pass-band, the lower the cutoff frequency will be.

D

Decrease In Signal Amplitude

A measurement on an oscilloscope that shows a negative slope. This can indicate a problem with the system’s power supply being measured, or it may mean that crosstalk or noise is being introduced into your signals.

Delay

Delay (also called Delay Line) describes how much time passes between a signal entering and exiting a device.

Delayed Time Base

The delayed time base is a feature found on some oscilloscopes. It allows users to set the horizontal sweep delay and capture more details about how events unfold over time.

Demodulated Signal

A signal that has been changed into its original format. For example, an AM signal that is demodulated will be changed to a standard sine wave.

Difference Mode Waveform

A difference mode waveform shows the difference between two voltages, rather than just showing one voltage on its own. For example, if you're measuring an AC signal with both common-mode and differential measurements, you'll see the difference between them on your waveform display.

Differential AC Voltage Measurement

When you measure the voltage of AC signals on an oscilloscope, differential AC voltage measurement connects your test leads to two different parts of a circuit at different voltages. This means that you'll measure both positive and negative differences in voltage, which can give you a more accurate idea of what's happening.

Differential Mode Waveform

A differential mode waveform shows voltage differences between two parts of a circuit, but it doesn't show the individual voltages at each point. It shows how different pins in a device behave with respect to one another. For example, you'll typically see the difference between an input voltage and output voltage in this mode.

Digital MultiMeter

A digital multimeter is an electronic measuring device that features several different measurement modes to give users precise information about how circuits work. They typically measure things like current, voltage, resistance, capacitance, and frequency.

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Discontinuity

A discontinuity is any break in the shape of a signal, which typically indicates a problem with how the device being tested is operating. Discontinuities can also show up as noise, incorrect waveforms, or jitter.

Differential Time Base

A differential time base is typically used to adjust the phase relationship between two signals. It's essential for applications like bandwidth limitation, which ismeasured in degrees.

Differential Voltage

The difference between one signal and another. You'll typically see this on an oscilloscope as an option that shows up automatically when you're using a differential input type with your probes. Differential voltage is the most common measurement type for oscilloscopes.

Dynamic Range

The dynamic range of an instrument is how much it can accurately measure in terms of voltage. Generally, better quality instruments will have a higher dynamic range and handle larger signals than their cheaper counterparts.

Difference In Timing

The difference between when an event starts and finishes and the total time that elapses between those two events. Oscilloscopes usually measure this by using different triggering modes (edge, pulse width, etc.)

Digital Channels

If you're working with things like serial buses on your oscilloscope, this feature is for you. It allows the instrument to break apart digital signals into multiple channels for easier measurement.

Digital Instruments

Devices that use digital signals to perform measurements on a system. They're becoming increasingly common, and most modern oscilloscopes have a digital display mode for displaying information about a circuit digitally.

Digital Logic Signals

Digital logic signals are electronic signals with only two states, which correspond to the values of voltage (0 or 1).

Digital Oscilloscope

A digital oscilloscope is a measurement device that displays data digitally instead of on an analog screen. They're popular because they can measure far more signals than their analog counterparts simultaneously, and they tend to have a better overall signal-to-noise ratio.

Digital Phosphor Oscilloscope (DPO)

A digital phosphor oscilloscope is the successor to the traditional analog oscilloscope. Instead of an analog display, it uses a digital screen with high resolution that can show many different signals at once.

Digital Sampling Oscilloscope

A digital sampling oscilloscope measures analog signals by converting them into digital values that are sent to the screen. Since it samples at an extremely high rate, this often results in a very accurate display of whatever you're measuring.

Direct Digital Synthesizer (DDS)

Many modern oscilloscopes have digital signal generators built right in, which are known as direct digital synthesizers. This works similarly to an external signal generator in that it generates waveforms, but it saves you the hassle of needing something else entirely.

Digital Signals

Digital signals use a series of “on and off” states to deliver information.

Digital Storage Oscilloscope (DSO)

A digital storage oscilloscope is an advanced digital oscilloscope that allows you to manually trigger measurements and then save the data for future use. They're helpful for long-term analysis, but they don't have as much flexibility as their analog counterparts.

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Display Characteristics

The display characteristics of an oscilloscope are the maximum frequency, pulse width, and amplitude that it can measure. These factors play a large part in how accurate your measurements will be to real-world values.

Display Modes

Oscilloscopes can display information in several different ways. The most common are the digital and analog display modes, but many oscilloscopes also include other types, like pulse width, intensity, persistence (static), and more.

Display Memory

Display memory is an oscilloscope memory that allows you to take measurements and save them for later use. Most oscilloscopes have some kind of display memory, although the amount varies from unit to unit.

Display Signals

Display signals are the measurements you can see on an oscilloscope's screen. They're displayed in real-time--it updates them as new data comes in.

Distribution Of Amplitude

A measurement that tells you how much power your signals have. It's expressed as a percentage and describes how much of the signal's overall power is at any given voltage level.

Dynamic Range

The ability of equipment to accurately measure small, fast fluctuations in electrical signals without giving false readings. Dynamic range is a crucial factor in the accuracy of oscilloscopes, and it's usually measured from 1Hz to 100MHz.

Division Control

Most oscilloscopes have a division control, which lets you set how much data it will display on one screen.

Dual And Multiple-trace Oscilloscopes

Dual and multiple-trace oscilloscopes have two or more displays, which allow you to see multiple signals simultaneously. They help compare different waveforms and get a better picture of what's going on in your circuit.

Dual-beam Oscilloscope

An oscilloscope that uses two beams of light to measure signals instead of one. Dual-beam oscilloscopes are more accurate than single-beam units because they use multiple amplifiers, which helps reduce noise interference.

Dual-trace Oscilloscopes

An oscilloscope that has two different displays so you can measure two signals at once. Dual-trace oscilloscopes are helpful in laboratory settings because they have a wide bandwidth and enable measurements on AC and DC signals.

E

Edges

Edges are sudden voltage changes in an electrical signal. Most oscilloscopes can measure how fast the signals change or their frequency.

Environmental Tolerances

Environmental tolerances are the operating conditions of an oscilloscope, including its maximum allowable temperature and atmospheric pressure when in use.

Extended Acquisition Mode (EAM)

An oscilloscope's extended acquisition mode allows it to take data samples continuously and create a single waveform from all those samples. This helps reduce noise interference and creates a more accurate picture of your signal than normal real-time mode.

External Trigger

An external trigger is a signal that comes from an outside source and triggers a 
measurement. For oscilloscopes, the most common external triggers come from computers via USB or LAN.

Effective Bits

The effective bits of an oscilloscope are how many bits it uses in its calculations. The more bits, the greater the dynamic range of signals it will be able to measure accurately.

Electrical Signal

A measurable quantity of electricity that can be used to provide information. Electrical signals include voltage and current, and they're measured in volts and amperes, respectively.

Electron Beam

The path that electrons take when an oscilloscope’s cathode accelerates them. A vacuum tube, called a cathode, emits electrons, which are then attracted to positively charged plates, called grids. The grids control the amount of electricity that enters an electron stream and bends it into different shapes.

Electronic Beam Deflection

Electronic beam deflection is how oscilloscopes deflect electron beams so they can be used to measure voltage. They do this by using electromagnetic coils that produce magnetic fields, which then pull on the electron stream in different ways, depending on how much electricity enters them.

Electronic Components

Electronic components are the basic building blocks of analog and digital circuits. Their 
values determine how electricity flows in a circuit, including resistors, capacitors, inductors, voltage sources, and current sources.

Envelope

How an oscilloscope displays electrical signals. You can plot an envelope by placing markers on your waveform at several points corresponding to your signal’s most significant voltage levels. If you plot the envelope, you’re creating a graph that shows voltage over time.

Equivalent-time Sampling

When using equivalent-time sampling, an oscilloscope takes samples on both the rising and falling sections of a waveform to produce a more accurate display than it would if it only sampled the peak.

External Source Impedance

The impedance of an oscilloscope's external source tells you how much the outside world will affect your measurements. The higher this number, the more likely it is that voltage changes in your source signal could be caused by something other than what you're trying to measure.

F

Field Service Applications

Field service applications refer to any time that an oscilloscope can be deployed in the field by engineers doing onsite work. Field service usually covers industrial settings, but it can also apply to any location that isn't a normal office or lab space.

Frequency

Frequency is the number of times something repeats per unit of time. 
In oscilloscopes, frequency also refers to how often your signal moves back and forth between 0 volts and its peak voltage level.

Frequency Components

Frequency components are the different frequencies that make up a single signal. Frequency components are what produce the distinct shape of the signal you're looking at on your oscilloscope.

Frequency Response

Frequency response is the quantitative measure of a system or device's output spectrum. It can be used to characterize that system’s dynamics and measures magnitude and phase in comparison with its input at any given frequency.

Frequency Signals

A frequency signal is an analog or digital representation of a voltage that moves up and down with time. All waveforms are made of frequency signals, but noise signals are not indicative of any particular frequency.

Function Generator

A function generator is a signal source that you use to create a waveform over a wide range of frequencies. It produces waveforms such as sine waves, square waves and triangular waves.

G

Glowing Trace

A glowing trace is any bright area on your oscilloscope's display that isn't part of the signal. The glowing trace could be caused by nearby neon lights, too much brightness in your measurement signal, or simply by an object in your field of view.

Ground

Ground is the reference point from which all your measurements are made. The ground on most oscilloscopes is connected to earth by a grounding wire, usually via a metal rod driven several feet into the earth.

Ground Clip

A ground clip is a short wire with alligator clips at either end. You use this to connect your oscilloscope's grounding wire to the ground reference point in an electrical device so that you can take measurements on it.

Ground Reference

A ground reference is a point in your circuit connecting to earth, most often with a grounding clip. You can use the ground reference to accurately measure voltages and currents on your circuit.

H

Handheld Oscilloscopes

Handheld oscilloscopes are designed to be small and portable. You can use them in the field to diagnose your equipment when it isn't practical to bring a bench oscilloscope for remote/off-site testing.

Horizontal Mode

This specifies whether your oscilloscope is currently in linear or log mode. Linear mode tells the oscilloscope to draw its waveforms in straight line segments, whereas log mode tells the oscilloscope to draw its waveforms in a logarithmic fashion. If your application requires you to see detailed high-frequency signals, then it's best to switch into log mode in order to take full advantage of what the oscilloscope has to offer.

Horizontal Offset

Horizontal offset refers to the difference between where your waveform initiates on an oscilloscope's display and where it would be if it started at 0 volts. A horizontal offset will appear as either positive or negative depending on whether it is above or below your ideal reference point.

Horizontal Position Control

Horizontal position control is a knob or button you use to adjust the horizontal positioning on your oscilloscope. It moves the waveform left and right to where you want it on the screen.

Horizontal Sweep

Horizontal sweep is the term used to describe how much time it takes for a waveform to go from one side of your screen to the other. You can control sweep speed in terms of seconds or milliseconds.

I

Incoming Signal

An incoming signal is any electrical signal that enters your oscilloscope through the input channels.

Industrial Applications

Industrial applications are measurements for your oscilloscope which you can't perform at home. They may include testing industrial machines, checking the output of industrial equipment, or monitoring noise in industrial environments.

Input Bandwidth

Input bandwidth is the range of frequencies that an oscilloscope can successfully measure. It is usually stated in terms of megahertz or gigahertz.

Input Coupling

Input coupling refers to how an oscilloscope channels incoming signals through its input channels. Different oscilloscopes use different input couplings for various purposes, but they are all included to allow you to see how your circuit will behave under different conditions.

Input Signal

An input signal is any electrical signal that enters your oscilloscope as a whole. This could be either a signal from an external source or a reflection of the circuit under test on your oscilloscope's input channels.

Input Voltage

Input voltage is the electrical potential at your oscilloscope's input channels. It varies depending on the source of the signal.

Input Waveform

Input waveform refers to the electrical signals that enter your oscilloscope's input channels. You use these waveforms to make measurements and analyze circuits.

Instruments

Instruments are pieces of equipment, such as an oscilloscope or a spectrum analyzer, that are used to test electrical circuits and devices.

Intensity Grading

Intensity grading is the act of adjusting the brightness of your oscilloscope's display to get the most out of its contrast.

Internal Trigger

An internal trigger is a signal that comes from within the oscilloscope and triggers a measurement. For this, we recommend using a square wave as your signal because it's easy to see what you're measuring on the screen. However, you can use any other kind of signal as your trigger as long as you understand what you're looking at and can explain it to others.

Interpolation

Interpolation is the process of using points with known values to estimate other unknown points. It is used on oscilloscopes to give you more detailed measurements of your waveform.

Interpolation Methods

There are two main types of interpolation used on oscilloscopes, linear interpolation and sineX/X.

Interval Mode

This specifies whether your oscilloscope is currently in the “Single Shot Mode” or the “Normal Continuous Mode”. In normal mode, your scope will continuously update itself with any changes that happen on its screen and is ideal if you're trying to perform real-time measurements. If you want to freeze a waveform, then the Single Shot Mode will take a single snapshot of it. This enables you to take extremely precise measurements.

L

Linear Interpolation

Linear interpolation works by creating an output point between two input points. A linear trendline is then fitted to the input points. The endpoint of the line is used as an approximation for the value at that point on your waveform.

Leading Edge

The leading edge of a waveform refers to the front, or first part, as it goes from low to high. It's also known as the ascending edge.

Level Knob

A level knob is a tool that lets you control the brightness of your oscilloscope display. It is usually located on the front panel and may be labeled as such or as “Gradient Level”.

Limit lines

Limit lines are drawn on an oscilloscope's screen as a visual aid for measuring points of interest. They indicate the extremes of your waveform both above and below the centerline.

Level Signals

A level signal is any electrical signal that stays at either your oscilloscope’s input channels’ high or low voltage levels.

Loading

Loading is the act of connecting your oscilloscope to your circuit or an external signal source. This is usually done with probes or cables.

Linear Interpolation

Linear interpolation works by creating an output point between two input points. A linear trendline is then fitted to the input points. The endpoint of the line is used as an approximation for the value at that point on your waveform.

M

Manual Mode

This specifies whether your oscilloscope is currently in manual or automatic mode. This determines how your oscilloscope behaves when it comes across an unknown signal. In manual mode, the oscilloscope will require trigger position inputs from you in order to measure what it can from that signal. If you're using this scope, then it's best to leave this in automatic mode unless you know for sure that your signal has a very specific critical point that you need to measure again later.

Maximum Voltage

The maximum voltage of an input signal is the highest potential that can ever come into your oscilloscope. It is important to know this, as it affects your minimum sensitivity setting.

Measurement Functions

Measurement functions are references that you use to take measurements on your oscilloscope. They include cursors, time/div, and math functions.

Measurement Signal

A measurement signal is any external electrical signal that you connect to your oscilloscope. It can come from a circuit's output, an external signal generator, or another test instrument.

Mhz Bandwidth

Mhz bandwidth is a measurement of the highest frequency that an oscilloscope can accurately measure. It's the difference between the lower and upper limits of your instrument's frequency range.

Minimal Controls

Oscilloscopes with minimal controls have a small number of knobs and a single screen. These typically have the basic measurements found on all oscilloscopes, such as volts/div and time/div.

Minimum Sample Rate

The minimum sample rate is the lowest frequency at which your oscilloscope can acquire and integrate data. It's usually stated in megahertz or gigahertz.

Mixed-signal Oscilloscope

A mixed-signal oscilloscope is one that can simultaneously display signals from both analog and digital sources.

Mode Of Operation

Mode of operation is the primary function that your oscilloscope performs at any given time.

Multi-trace Oscilloscopes

Multi-trace oscilloscopes are designed to display multiple signals at once. They're often used to compare the various waveforms of a circuit.

N

Negative Slope

A negative slope means that two variables are negatively related; in other words, as one variable increases, the other value decreases and vice versa. Graphically speaking, as the line moves from left to right, the line will descend.

O

Oscilloscope Display

An oscilloscope display is the screen of an oscilloscope that shows electrical signals.

Oscilloscope Input

Oscilloscope inputs are the two channels of an oscilloscope – vertical and horizontal.

P

Peak Voltage (vP)

Peak voltage is the maximum voltage that an electrical signal ever reaches as measured from a zero-volt level.

Peak Detection

Peak detection is a measurement function that identifies the maximum and minimum values of an electrical signal.

Peak-to-peak (vp-p)

Peak-to-peak describes a waveform that varies between a maximum and minimum value.

Period

A period is the time it takes for a waveform to repeat itself. It's usually stated in seconds.

Period Of Time

Period of time is an interval of time, such as seconds or milliseconds.

Phase

Phase is a measurement of an electrical signal's position along a time scale. It's expressed in degrees. A complete waveform cycle is said to be 360 degrees of phase.

Phase Differences

Phase differences are the amount of time between two repeating signals. For example, if one signal leads another by 30 degrees, one waveform is delayed by half a cycle behind the nother.

Phase Shift

Phase shift is when one voltage leads or lags another voltage by some number of degrees.

Polarity

The polarity of a signal refers to the voltage difference between two points that make up your device's circuit. Using a square wave as an example, if you look at the top and bottom of the waveform, then you will notice that one is positive and the other negative.

Pre-trigger Viewing

Pre-trigger viewing is a setting on an oscilloscope that allows you to view measurements before the trigger. This feature is useful when capturing events leading up to some event (like load voltage changes before a power outage).

Probe

A probe is an instrument used to connect your oscilloscope with the circuit or device that you're testing. Probes are usually made up of two parts: a cable that attaches to the oscilloscope’s ground connection, and a probe tip that connects with your circuit.

Probe Delay

Probe delay is the length of time it takes for a signal from a signal generator to travel from its probe tip, through your device's circuit, and back to the oscilloscope's input.

Pulse Width

The Pulse Width (PW) is the ..elapsed time between each pulse.

R

Ramp Waveform

A ramp waveform is a sinusoidal pattern that starts at zero and rises continuously to a maximum value.

Range

The range of the oscilloscope is how wide of a voltage difference it can measure. For example, if your instrument can measure up to 10 volts, you should use probes with a 10-volt rating.

Raster Display

Raster displays are Cathode Ray Tubes (CRTs) that display images by moving a beam of electrons across the screen.

Real Signal

A real signal is an electrical signal that may actually exist in the physical world. A perfect example of a real signal on an oscilloscope would be a sine wave.

Real-time Sampling

Real-time sampling is when you see your waveform update on the screen of an oscilloscope in real-time.

Record Length

Oscilloscopes capture a specified number of samples or data points, called the record length for each acquired waveform. The record length specifies the total length of time acquired.

Reference Signal

A reference signal is any waveform that can provide a time standard. Most oscilloscopes include an internal oscillator that serves as the system's clock and provides this timing reference. You can also use signals from other devices or instruments as references for your measurements if your scope has them available.

Repetitive Signals

Repetitive signals are waveforms in which a similar pattern repeats itself. For example, a sine wave in which the peak and trough values remain constant would be a repetitive signal because it displays the identical cycle repeatedly.

Rise Time

Rise time is the time it takes for an electrical signal to transition from 10% to 90% of its voltage. Rise time is usually measured in nanoseconds (ns).

S

Sample Point

A sample point is a single reading of an electrical signal at any given point in time. This measurement is taken by an oscilloscope and used for analysis.

Sampling Mode

Sampling mode is the oscilloscope's method of collecting and measuring multiple voltage samples at a time. Samples are collected in pairs, depending on how your scope is set to acquire data. You can set your sampling mode to either single-shot or repetitive.

Sampling Rate

The sampling rate is the frequency at which analog signals are sampled or digitized by your instrument. For example, if your scope can sample at 100 MHz every one-millionth of a second, it will take these measurements and store them to be viewed later. Oscilloscope sweeps are created in this manner.

Scopes

An oscilloscope is an instrument that allows you to see how changing electrical signals behave over time. These devices are used in many industries to provide insight into what's happening when things go wrong, or when there are problems with a circuit.

Selector Knob

A selector knob is the primary mode of control for an oscilloscope. You use this knob to select or adjust your settings.

Signal

Signal is the term used to describe an analog electrical voltage varience. A signal can be analog, like voltage or current, ordigital, like a binary bitstream of 1s and 0s.

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Signal Characteristics

Signal characteristics tell you how well your signal is functioning. These include magnitude, range, amplitude, frequency, dynamic, static, deterministic, non-deterministic, mean, and RMS (root-means-square).

Signal Details

Signal details tell you all about your signal. For example, they can tell you the size of the voltage peaks, relative amplitude in fixed-sized units, and crest factor.

Signal Frequencies

Signal frequencies tell you how often your signal repeats per unit of time. Frequency can be expressed in hertz (Hz), kilohertz (KHz), megahertz (MHz), and gigahertz (GHz).

Signal Integrity

Signal integrity refers to the quality of your signal. This includes the number of timing errors, distortion, crosstalk, and attenuation.

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Signal Source

A signal source is the device that provides asignal to the scope. This can be an instrument, such as a function generator, another scope, or another piece of test equipment.

Signal Swing

Signal swing is the percent difference between the smallest and largest signals that your oscilloscope can display. For example, if your signal swings from -5V to +15V, you would say it has a 50% signal swing.

Signal Types

There are two types of signals: analog and digital. Analog signals are electrical voltages that vary over time. Digital signals also vary over time, but only have two voltage states: +V and -V.

Signal Voltages

Signal voltages are the electrical voltages in your signals that range between ground and some upper limit. This can be stated as a percentage or in volts DC (VDC) when negative. For example, if your signal varies from -5V to +3V, it's at 40%.

Signal Waveform

A signal waveform is the pattern of your signal over time. This pattern represents the voltage over time for an analog signal and the sequence of values for a digital signal.

Sine Wave

A sine wave is the most basic type of signal. It's a smooth, repetitive oscillation that repeats itself without interruption. A sine wave looks like a wavy line on an oscilloscope display.

SineX/X

The sineX/X interpolation method uses linear interpolation to estimate the first point. The remaining points are then estimated by fitting a sine function between each consecutive pair of linear approximations.

Single Shot

A single-shot trigger occurs when the oscilloscope triggers on a single event and does not repeat.

Single Sweep

A single sweep is one complete cycle of the oscilloscope's CRT beam. This occurs when it moves from left to right and then returns to zero volts in preparation for the next sweep.

Slope

The slope is the rate of change in your waveform. It's the measure of how steep or shallow your waveform is at any given time.

Special-purpose Oscilloscopes

Some oscilloscopes are designed for specific testing tasks. These include logic analysis, automotive, high-speed digital, and microwave oscilloscopes.

Speed Error

Speed error is the phase difference between a signal's actual frequency and its display.

Square Waves

A square wave displays sharp transitions between high and low voltages that look like a square or rectangular shape on an oscilloscope display. They're used in digital analysis because the signal easily filters out undesired frequencies.

Sweep

Sweep refers to the horizontal motion of the oscilloscope beam on your display. This is caused by sweeping or repetitively scanning the CRT left to right across the screen. A single sweep moves from left to right and then returns to zero volts in preparation for the next sweep.

Sweep Circuit

A sweep circuit is an electrical component that controls how fast your CRT beam moves across the screen. It also enables it to start at any point along the horizontal axis.

Sweep Repetition Rate

The sweep repetition rate (SRR) is the number of times your signal moves across the screen per second. If you have an SRR of 5 ms, your beam will move left and right five times each second.

Sweep Speed

Sweep speed is the velocity of your CRT beam as it moves across the screen. It's measured in inches or centimeters per second.

T

Time Base

The time base is the interval of time that's represented on each division of an oscilloscope. It controls the vertical position of your CRT beam or how far it jumps up or down when you trigger an event.

Time Base Sweep

Time base sweep refers to the oscilloscope's vertical scanning circuit. A single-time base sweep moves from top to bottom and then returns to zero volts in preparation for the next sweep.

Time Constants

Time constants are the time periods associated with a given electrical component.

Time Interval

A time interval is a specific length of time. It's used to set the amplitude and duration of a waveform on your oscilloscope.

Time Scale

A time scale is a type of measurement for any given waveform. It's used to set the amplitude and duration of a waveform on your oscilloscope.

Time Scale Setting

A time scale setting is the act of changing your oscilloscope's horizontal mode to accommodate a given waveform.

Timing

Timing is the ability of your oscilloscope to take measurements. It's affected by internal memory limitations and processing speed.

Timing Relationship

A timing relationship is the relationship/alignmment between two or more signals so that you can see how they relate to one another. This may be done by triggering or delaying one signal relative to another.

Trace

A trace is a line that appears on your screen representing the actual waveform you're measuring.

Trace Separation Control

The trace separation control is a feature that changes the spacing between multiple waveforms. If you take more than one simultaneous measurement, you can easily use this setting to distinguish between them.

Transient

A transient is an event, waveform, or signal that doesn't last very long.

Transient Event

A transient event is any change in the signal voltage. This could be the result of a pulse, glitch, or noise.

Trigger

The trigger function on an oscilloscope is what synchronizes the horizontal sweep to any point in time. Trigger controls are used to stabilize repetitive waveforms and capture single-shot waveforms.

Trigger Circuit

The trigger circuit is the electrical component that controls how your oscilloscope triggers.

Trigger Event

A trigger event is any vertical change in the input signal to your oscilloscope. This could be caused by a glitch, noise burst, or pulse.

Trigger Holdoff

Trigger holdoff is the disabling of your oscilloscope trigger for a given amount of time. This ensures that you don't capture multiple data points from spurious noise.

Trigger Level

The trigger level control provides the basic trigger point definition and determines how a waveform is displayed.

Trigger Mode

Trigger mode is the setting that dictates how your oscilloscope triggers. There are three standard trigger modes: auto, normal, and single.

Trigger Sensitivity

This specifies how sensitively your scope responds to triggers, so if you have a low trigger sensitivity then your scope will require a stronger signal to trigger. You might find this useful if you are measuring fast signals, as otherwise, triggering on every single little noise would become annoying.

Trigger Slope

The trigger slope is the triggering method of your oscilloscope. It's either positive or negative edge sensitive.

Trigger Source Signal

A trigger source is an input that controls when your oscilloscope triggers. You can choose from channels, external and internal.

Trigger Type

Trigger types are used to specify how your oscilloscope will trigger on a signal. You can think of it as the first step in setting up your measurement. For example, if you're using an external probe then you might choose Normal for Trigger Type, but if you're using Channel 1 with its built-in preamp and attenuator, then you might choose Auto.

V

Vertical Channels

Vertical channels are the oscilloscope's input channels. They measure a specific time interval and voltage value for a single channel.

Vertical Controls

The vertical controls are the settings that affect voltage measurements on your screen. They include vertical position, coupling, and attenuation.

Vertical Division

A vertical division is a measurement of time, determined by the vertical position control. It's used to set the amplitude and duration of a waveform on your oscilloscope.

Vertical Input Signal

The vertical input signal is the waveform, or voltage, appearing at a particular point in time and space. The oscilloscope’s vertical input channel detects it.

Vertical Mode

When using an oscilloscope's vertical mode, you are instructing your oscilloscope to display which channel it is reading at any given time.

Vertical Offset

The vertical offset control offsets your oscilloscope's voltage measurement. This is often used to compensate for attenuation or to maximize displayed amplitude.

Vertical Position Control

The vertical position control sets the time interval that you measure on your screen. It can also be used to lengthen or shorten waveforms shown on your oscilloscope.

Vertical Resolution

Vertical resolution is the smallest increment of measurement that your oscilloscope can distinguish. This determines how finely you can measure the voltage on an oscilloscope screen.

Vertical Scale

This specifies how quickly the vertical axis should scroll through your oscilloscope's display. It can be displayed in “volts per division” or as a percentage of full scale. Of course, this will vary, depending on which scope you are using, but it is helpful to understand what this means, regardless of which oscilloscope you are using

Vertical Sensitivity

The vertical sensitivity control changes the level or height at which a waveform appears on your oscilloscope's screen. This is often compared with the trigger level control.

Vertical Signal Input

Vertical signal input is the oscilloscope's voltage, terminal, or channel, that measures time intervals. This term refers to all of an oscilloscope's inputs.

Visible Trace Width

The visible trace width is the area that a waveform occupies on your oscilloscope's screen. This also refers to the oscilloscope channel setting.

W

Waveform

A waveform is the graphical representation of a voltage. It's typically shown as a line, but can also be a curve or numeric display.

Waveform Capture Rate

The waveform capture rate, also called the sweep speed, is the oscilloscope's measurement of a waveform over a set time interval. It can be changed to show a different quantity or duration.

Waveform Display Area

The waveform display area is the location on your oscilloscope screen where you see a given waveform.

Waveform Point

A waveform point is a single data point on your oscilloscope screen that appears as a cross mark.

Waveform Repetitions

A waveform repetition is the full cycle of a waveform. It corresponds to the total amount of time it takes for something to occur, whether that's voltage or time.

Window

This is an advanced feature that can be enabled on your oscilloscope which allows you to zoom in and out of a particular waveform. It's often used when there is a high-frequency component of a signal that you would like to see more clearly, but don't necessarily care to measure at the specific frequency. Let's say you're measuring a 10MHz signal, but you're using a 20MHz oscilloscope. If you enable the scope's window, then it will display a zoomed view of the most important part of that high-frequency waveform.

Writing Speed

The writing speed is the oscilloscope's speed at which data is written to a storage medium. The higher this is, the faster your device can capture and store waveforms.

X

X-y Mode

X-y mode is a way to display voltage versus time on your oscilloscope. It is the most common type of measurement, and it has both horizontal and vertical axes.

Z

Z-Axis

The z-axis is the axis in 3-D space where an oscilloscope measures the third dimension. Z is often used to represent a third voltage channel.

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