Oscilloscope

This article is about current oscilloscopes, providinggeneral information. For history of oscilloscopes, seeOscilloscope history. For detailed information about var-ious types of oscilloscopes, see Oscilloscope types. Forthe lm distributor, see Oscilloscope Laboratories.

An oscilloscope, previously called an

The interior of a cathode-ray tube for use in an oscilloscope. 1.Deection voltage electrode; 2. Electron gun; 3. Electron beam;4. Focusing coil; 5. Phosphor-coated inner side of the screen

A Tektronix model 475A portable analog oscilloscope, a verytypical instrument of the late 1970s

oscillograph,[1][2] and informally known as a scope,CRO (for cathode-ray oscilloscope), or DSO (for themore modern digital storage oscilloscope), is a typeof electronic test instrument that allows observation ofconstantly varying signal voltages, usually as a two-dimensional plot of one or more signals as a function oftime. Non-electrical signals (such as sound or vibration)can be converted to voltages and displayed.Oscilloscopes are used to observe the change of an elec-trical signal over time, such that voltage and time de-scribe a shape which is continuously graphed against a

Amodern PicoScope 6000USB digital oscilloscope using a laptopcomputer for its display

A modern Siglent SHS800 handheld digital storage oscilloscope(DSO) using an LCD for its display

calibrated scale. The observed waveform can be ana-lyzed for such properties as amplitude, frequency, risetime, time interval, distortion and others. Modern digi-tal instruments may calculate and display these propertiesdirectly. Originally, calculation of these values requiredmanually measuring the waveform against the scales builtinto the screen of the instrument.[3]

The oscilloscope can be adjusted so that repetitive signalscan be observed as a continuous shape on the screen. A

1

2 1 FEATURES AND USES

An oscilloscope displaying capacitor discharge

storage oscilloscope allows single events to be captured bythe instrument and displayed for a relatively long time, al-lowing human observation of events too fast to be directlyperceptible.Oscilloscopes are used in the sciences, medicine, en-gineering, and telecommunications industry. General-purpose instruments are used for maintenance of elec-tronic equipment and laboratory work. Special-purposeoscilloscopes may be used for such purposes as analyzingan automotive ignition system or to display the waveformof the heartbeat as an electrocardiogram.Before the advent of digital electronics, oscilloscopesused cathode ray tubes (CRTs) as their display element(hence were commonly referred to as CROs) and linearampliers for signal processing. Storage oscilloscopesused special storage CRTs to maintain a steady display ofa single brief signal. CROs were later largely supersededby digital storage oscilloscopes (DSOs) with thin paneldisplays, fast analog-to-digital converters and digital sig-nal processors. DSOs without integrated displays (some-times known as digitisers) are available at lower cost anduse a general-purpose digital computer to process and dis-play waveforms.

1 Features and uses

1.1 DescriptionThe basic oscilloscope, as shown in the illustration, is typ-ically divided into four sections: the display, vertical con-trols, horizontal controls and trigger controls. The displayis usually a CRT or LCD panel which is laid out with bothhorizontal and vertical reference lines referred to as thegraticule. In addition to the screen, most display sectionsare equipped with three basic controls: a focus knob, anintensity knob and a beam nder button.The vertical section controls the amplitude of the dis-played signal. This section carries a Volts-per-Division(Volts/Div) selector knob, an AC/DC/Ground selector

Basic oscilloscope

switch and the vertical (primary) input for the instrument.Additionally, this section is typically equipped with thevertical beam position knob.The horizontal section controls the time base or sweepof the instrument. The primary control is the Seconds-per-Division (Sec/Div) selector switch. Also included isa horizontal input for plotting dual X-Y axis signals. Thehorizontal beam position knob is generally located in thissection.The trigger section controls the start event of the sweep.The trigger can be set to automatically restart after eachsweep or it can be congured to respond to an internal orexternal event. The principal controls of this section willbe the source and coupling selector switches. An externaltrigger input (EXT Input) and level adjustment will alsobe included.In addition to the basic instrument, most oscilloscopes aresupplied with a probe as shown. The probe will connect toany input on the instrument and typically has a resistor often times the oscilloscopes input impedance. This resultsin a .1 (10X) attenuation factor, but helps to isolate thecapacitive load presented by the probe cable from the sig-nal being measured. Some probes have a switch allowingthe operator to bypass the resistor when appropriate.[3]

1.1.1 Size and portability

Most modern oscilloscopes are lightweight, portable in-struments that are compact enough to be easily carriedby a single person. In addition to the portable units, themarket oers a number of miniature battery-powered in-struments for eld service applications. Laboratory gradeoscilloscopes, especially older units which use vacuumtubes, are generally bench-top devices ormay bemountedinto dedicated carts. Special-purpose oscilloscopes maybe rack-mounted or permanently mounted into a custom

1.1 Description 3

instrument housing.

1.1.2 Inputs

The signal to be measured is fed to one of the input con-nectors, which is usually a coaxial connector such as aBNC or UHF type. Binding posts or banana plugs maybe used for lower frequencies. If the signal source hasits own coaxial connector, then a simple coaxial cableis used; otherwise, a specialised cable called a "scopeprobe", supplied with the oscilloscope, is used. In gen-eral, for routine use, an open wire test lead for connect-ing to the point being observed is not satisfactory, anda probe is generally necessary. General-purpose oscillo-scopes usually present an input impedance of 1 megohmin parallel with a small but known capacitance such as 20picofarads.[4] This allows the use of standard oscilloscopeprobes.[5] Scopes for use with very high frequencies mayhave 50ohm inputs, which must be either connected di-rectly to a 50ohm signal source or used with Z0 or activeprobes.Less-frequently-used inputs include one (or two) for trig-gering the sweep, horizontal deection for XYmode dis-plays, and trace brightening/darkening, sometimes calledz'axis inputs.

1.1.3 Probes

Main article: Test probe Oscilloscope probes

Open wire test leads (ying leads) are likely to pick upinterference, so they are not suitable for low level signals.Furthermore, the leads have a high inductance, so they arenot suitable for high frequencies. Using a shielded cable(i.e., coaxial cable) is better for low level signals. Coaxialcable also has lower inductance, but it has higher capaci-tance: a typical 50 ohm cable has about 90 pF per meter.Consequently, a one meter direct (1X) coaxial probe willload a circuit with a capacitance of about 110 pF and aresistance of 1 megohm.To minimize loading, attenuator probes (e.g., 10Xprobes) are used. A typical probe uses a 9 megohm se-ries resistor shunted by a low-value capacitor to makean RC compensated divider with the cable capacitanceand scope input. The RC time constants are adjustedto match. For example, the 9 megohm series resistor isshunted by a 12.2 pF capacitor for a time constant of 110microseconds. The cable capacitance of 90 pF in parallelwith the scope input of 20 pF and 1 megohm (total ca-pacitance 110 pF) also gives a time constant of 110 mi-croseconds. In practice, there will be an adjustment sothe operator can precisely match the low frequency timeconstant (called compensating the probe). Matching thetime constants makes the attenuation independent of fre-quency. At low frequencies (where the resistance of R ismuch less than the reactance of C), the circuit looks like

a resistive divider; at high frequencies (resistance muchgreater than reactance), the circuit looks like a capacitivedivider.[6]

The result is a frequency compensated probe for mod-est frequencies that presents a load of about 10 megohmsshunted by 12 pF. Although such a probe is an improve-ment, it does not work when the time scale shrinks toseveral cable transit times (transit time is typically 5 ns).In that time frame, the cable looks like its character-istic impedance, and there will be reections from thetransmission line mismatch at the scope input and theprobe that causes ringing.[7] The modern scope probeuses lossy low capacitance transmission lines and so-phisticated frequency shaping networks to make the 10Xprobe perform well at several hundred megahertz. Con-sequently, there are other adjustments for completing thecompensation.[8][9]

Probes with 10:1 attenuation are by far the most com-mon; for large signals (and slightly-less capacitive load-ing), 100:1 probes are not rare. There are also probes thatcontain switches to select 10:1 or direct (1:1) ratios, butone must be aware that the 1:1 setting has signicant ca-pacitance (tens of pF) at the probe tip, because the wholecables capacitance is now directly connected.Most oscilloscopes allow for probe attenuation factors,displaying the eective sensitivity at the probe tip.Historically, some auto-sensing circuitry used indicatorlamps behind translucent windows in the panel to illumi-nate dierent parts of the sensitivity scale. To do so, theprobe connectors (modied BNCs) had an extra contactto dene the probes attenuation. (A certain value of re-sistor, connected to ground, encodes the attenuation.)Because probes wear out, and because the auto-sensingcircuitry is not compatible between dierent makes ofoscilloscope, auto-sensing probe scaling is not foolproof.Likewise, manually setting the probe attenuation is proneto user error and it is a commonmistake to have the probescaling set incorrectly; resultant voltage readings can thenbe wrong by a factor of 10.There are special high voltage probes which also formcompensated attenuators with the oscilloscope input; theprobe body is physically large, and some require partlylling a canister surrounding the series resistor withvolatile liquid uorocarbon to displace air. At the os-cilloscope end is a box with several waveform-trimmingadjustments. For safety, a barrier disc keeps ones n-gers distant from the point being examined. Maximumvoltage is in the low tens of kV. (Observing a high volt-age ramp can create a staircase waveform with steps atdierent points every repetition, until the probe tip is incontact. Until then, a tiny arc charges the probe tip, andits capacitance holds the voltage (open circuit). As thevoltage continues to climb, another tiny arc charges thetip further.)There are also current probes, with cores that surroundthe conductor carrying current to be examined. One type

4 1 FEATURES AND USES

has a hole for the conductor, and requires that the wirebe passed through the hole; they are for semi-permanentor permanent mounting. However, other types, for test-ing, have a two-part core that permit them to be placedaround a wire. Inside the probe, a coil wound around thecore provides a current into an appropriate load, and thevoltage across that load is proportional to current. How-ever, this type of probe can sense AC, only.A more-sophisticated probe includes a magnetic ux sen-sor (Hall eect sensor) in the magnetic circuit. The probeconnects to an amplier, which feeds (low frequency) cur-rent into the coil to cancel the sensed eld; the magnitudeof that current provides the low-frequency part of the cur-rent waveform, right down to DC. The coil still picks uphigh frequencies. There is a combining network akin toa loudspeaker crossover network.

1.2 Front panel controls1.2.1 Focus control

This control adjusts CRT focus to obtain the sharpest,most-detailed trace. In practice, focus needs to be ad-justed slightly when observing quite-dierent signals,which means that it needs to be an external control. Flat-panel displays do not need focus adjustments and there-fore do not include this control.

1.2.2 Intensity control

This adjusts trace brightness. Slow traces on CRT oscil-loscopes need less, and fast ones, especially if not oftenrepeated, require more. On at panels, however, tracebrightness is essentially independent of sweep speed, be-cause the internal signal processing eectively synthe-sizes the display from the digitized data.

1.2.3 Astigmatism

Can also be called Shape or spot shape. Adjusts therelative voltages on two of the CRT anodes such that a dis-played spot changes from elliptical in one plane througha circular spot to an ellipse at 90 degrees to the rst. Thiscontrol may be absent from simpler oscilloscope designsor may even be an internal control. It is not necessarywith at panel displays.

1.2.4 Beam nder

Modern oscilloscopes have direct-coupled deection am-pliers, which means the trace could be deected o-screen. They also might have their beam blanked with-out the operator knowing it. To help in restoring a visi-ble display, the beam nder circuit overrides any blankingand limits the beam deected to the visible portion of the

screen. Beam-nder circuits often distort the trace whileactivated.

1.2.5 Graticule

The graticule is a grid of squares that serve as referencemarks for measuring the displayed trace. These mark-ings, whether located directly on the screen or on a re-movable plastic lter, usually consist of a 1 cm grid withcloser tick marks (often at 2 mm) on the centre verticaland horizontal axis. One expects to see ten major di-visions across the screen; the number of vertical majordivisions varies. Comparing the grid markings with thewaveform permits one to measure both voltage (verticalaxis) and time (horizontal axis). Frequency can also bedetermined by measuring the waveform period and cal-culating its reciprocal.On old and lower-cost CRT oscilloscopes the graticule isa sheet of plastic, often with light-diusing markings andconcealed lamps at the edge of the graticule. The lampshad a brightness control. Higher-cost instruments havethe graticule marked on the inside face of the CRT, toeliminate parallax errors; better ones also had adjustableedge illumination with diusing markings. (Diusingmarkings appear bright.) Digital oscilloscopes, however,generate the graticule markings on the display in the sameway as the trace.External graticules also protect the glass face of the CRTfrom accidental impact. Some CRT oscilloscopes withinternal graticules have an unmarked tinted sheet plasticlight lter to enhance trace contrast; this also serves toprotect the faceplate of the CRT.Accuracy and resolution of measurements using a gratic-ule is relatively limited; better instruments sometimeshave movable bright markers on the trace that permit in-ternal circuits to make more rened measurements.Both calibrated vertical sensitivity and calibrated hori-zontal time are set in 1 - 2 - 5 - 10 steps. This leads,however, to some awkward interpretations of minor divi-sions

1.2.6 Timebase controls

These select the horizontal speed of the CRTs spot asit creates the trace; this process is commonly referred toas the sweep. In all but the least-costly modern oscillo-scopes, the sweep speed is selectable and calibrated inunits of time per major graticule division. Quite a widerange of sweep speeds is generally provided, from sec-onds to as fast as picoseconds (in the fastest) per divi-sion. Usually, a continuously-variable control (often aknob in front of the calibrated selector knob) oers un-calibrated speeds, typically slower than calibrated. Thiscontrol provides a range somewhat greater than that ofconsecutive calibrated steps, making any speed available

1.2 Front panel controls 5

Computer Model of the impact of increasing the timebasetime/division.

between the extremes.

1.2.7 Holdo control

Found on some better analog oscilloscopes, this varies thetime (holdo) during which the sweep circuit ignores trig-gers. It provides a stable display of some repetitive eventsin which some triggers would create confusing displays.It is usually set to minimum, because a longer time de-creases the number of sweeps per second, resulting in adimmer trace. See Holdo for a more detailed descrip-tion.

1.2.8 Vertical sensitivity, coupling, and polaritycontrols

To accommodate a wide range of input amplitudes, aswitch selects calibrated sensitivity of the vertical de-ection. Another control, often in front of the calibrated-selector knob, oers a continuously-variable sensitiv-ity over a limited range from calibrated to less-sensitivesettings.Often the observed signal is oset by a steady compo-nent, and only the changes are of interest. A switch(AC position) connects a capacitor in series with the in-put that passes only the changes (provided that they arenot too slow -- slow would mean visible). However,when the signal has a xed oset of interest, or changesquite slowly, the input is connected directly (DC switchposition). Most oscilloscopes oer the DC input op-tion. For convenience, to see where zero volts input cur-rently shows on the screen, many oscilloscopes have athird switch position (GND) that disconnects the inputand grounds it. Often, in this case, the user centers thetrace with the Vertical Position control.Better oscilloscopes have a polarity selector. Normally,a positive input moves the trace upward, but this permitsinvertingpositive deects the trace downward.

1.2.9 Horizontal sensitivity control

This control is found only on more elaborate oscillo-scopes; it oers adjustable sensitivity for external hori-zontal inputs.

1.2.10 Vertical position control

Computer model of Vertical position Y oset varying in a sineway

The vertical position control moves the whole displayedtrace up and down. It is used to set the no-input traceexactly on the center line of the graticule, but also per-mits osetting vertically by a limited amount. With di-rect coupling, adjustment of this control can compensatefor a limited DC component of an input.

1.2.11 Horizontal position control

Computer model of Horizontal position control from X oset in-creasing

The horizontal position control moves the display side-wise. It usually sets the left end of the trace at the leftedge of the graticule, but it can displace the whole tracewhen desired. This control also moves the X-Y modetraces sidewise in some instruments, and can compensatefor a limited DC component as for vertical position.

1.2.12 Dual-trace controls

* (Please see Dual and Multiple-trace Oscilloscopes, be-low.)

6 1 FEATURES AND USES

Dual-trace controls green trace = Y = 30*sin(0.1*t)+0.5 tealtrace = Y = 30*sin(0.3*t)

Each input channel usually has its own set of sensitivity,coupling, and position controls, although some four-traceoscilloscopes have only minimal controls for their thirdand fourth channels.Dual-trace oscilloscopes have amode switch to select ei-ther channel alone, both channels, or (in some) an XYdisplay, which uses the second channel for X deection.When both channels are displayed, the type of channelswitching can be selected on some oscilloscopes; on oth-ers, the type depends upon timebase setting. If manuallyselectable, channel switching can be free-running (asyn-chronous), or between consecutive sweeps. Some Philipsdual-trace analog oscilloscopes had a fast analog multi-plier, and provided a display of the product of the inputchannels.Multiple-trace oscilloscopes have a switch for each chan-nel to enable or disable display of that traces signal.

1.2.13 Delayed-sweep controls

* (Please see Delayed Sweep, below.)These include controls for the delayed-sweep timebase,which is calibrated, and often also variable. The slowestspeed is several steps faster than the slowest main sweepspeed, although the fastest is generally the same. A cal-ibrated multiturn delay time control oers wide range,high resolution delay settings; it spans the full duration ofthe main sweep, and its reading corresponds to graticuledivisions (but with much ner precision). Its accuracy isalso superior to that of the display.A switch selects display modes: Main sweep only, with abrightened region showing when the delayed sweep is ad-vancing, delayed sweep only, or (on some) a combinationmode.Good CRT oscilloscopes include a delayed-sweep inten-sity control, to allow for the dimmer trace of a much-faster delayed sweep that nevertheless occurs only oncepermain sweep. Such oscilloscopes also are likely to havea trace separation control for multiplexed display of boththe main and delayed sweeps together.

1.2.14 Sweep trigger controls

* (Please see Triggered Sweep, below.)A switch selects theTrigger Source. It can be an externalinput, one of the vertical channels of a dual or multiple-trace oscilloscope, or the AC line (mains) frequency. An-other switch enables or disables Auto trigger mode, orselects single sweep, if provided in the oscilloscope. Ei-ther a spring-return switch position or a pushbutton armssingle sweeps.ALevel control varies the voltage on the waveform whichgenerates a trigger, and the Slope switch selects positive-going or negative-going polarity at the selected triggerlevel.

1.3 Basic types of sweep

1.3.1 Triggered sweep

Type 465 Tektronix oscilloscope. This was a popular analog os-cilloscope, portable, and is a representative example.

To display events with unchanging or slowly (visibly)changing waveforms, but occurring at times that may notbe evenly spaced, modern oscilloscopes have triggeredsweeps. Compared to simpler oscilloscopes with sweeposcillators that are always running, triggered-sweep oscil-loscopes are markedly more versatile.A triggered sweep starts at a selected point on the sig-nal, providing a stable display. In this way, triggering al-lows the display of periodic signals such as sine waves andsquare waves, as well as nonperiodic signals such as singlepulses, or pulses that do not recur at a xed rate.With triggered sweeps, the scope will blank the beamand start to reset the sweep circuit each time the beamreaches the extreme right side of the screen. For a pe-riod of time, called holdo, (extendable by a front-panelcontrol on some better oscilloscopes), the sweep circuitresets completely and ignores triggers. Once holdo ex-pires, the next trigger starts a sweep. The trigger event isusually the input waveform reaching some user-specied

1.3 Basic types of sweep 7

threshold voltage (trigger level) in the specied direction(going positive or going negativetrigger polarity).In some cases, variable holdo time can be really usefulto make the sweep ignore interfering triggers that occurbefore the events one wants to observe. In the case ofrepetitive, but quite-complex waveforms, variable hold-o can create a stable display that cannot otherwise prac-tically be obtained.

1.3.2 Holdo

Trigger holdo denes a certain period following a trig-ger during which the scope will not trigger again. Thismakes it easier to establish a stable view of a waveformwith multiple edges which would otherwise cause anothertrigger.[10]

Example Imagine the following repeating waveform:

The green line is the waveform, the red vertical partialline represents the location of the trigger, and the yellowline represents the trigger level. If the scope was simplyset to trigger on every rising edge, this waveform wouldcause three triggers for each cycle:

Assuming the signal is fairly high frequency, the scopewould probably look something like this:

Except that on the scope, each trigger would be the samechannel, and so would be the same color.It is desired to set the scope to only trigger on one edgeper cycle, so it is necessary to set the holdo to be slightlyless than the period of the waveform. That will prevent itfrom triggering more than once per cycle, but still allowit to trigger on the rst edge of the next cycle.

1.3.3 Automatic sweep mode

Triggered sweeps can display a blank screen if there areno triggers. To avoid this, these sweeps include a timingcircuit that generates free-running triggers so a trace isalways visible. Once triggers arrive, the timer stops pro-viding pseudo-triggers. Automatic sweep mode can bede-selected when observing low repetition rates.

1.3.4 Recurrent sweeps

If the input signal is periodic, the sweep repetition ratecan be adjusted to display a few cycles of the waveform.Early (tube) oscilloscopes and lowest-cost oscilloscopeshave sweep oscillators that run continuously, and are un-calibrated. Such oscilloscopes are very simple, compara-tively inexpensive, and were useful in radio servicing andsome TV servicing. Measuring voltage or time is possi-ble, but only with extra equipment, and is quite inconve-nient. They are primarily qualitative instruments.They have a few (widely spaced) frequency ranges, andrelatively wide-range continuous frequency control withina given range. In use, the sweep frequency is set to slightlylower than some submultiple of the input frequency, todisplay typically at least two cycles of the input signal (soall details are visible). A very simple control feeds an ad-justable amount of the vertical signal (or possibly, a re-lated external signal) to the sweep oscillator. The signaltriggers beam blanking and a sweep retrace sooner thanit would occur free-running, and the display becomes sta-ble.

1.3.5 Single sweeps

Some oscilloscopes oer thesethe sweep circuit ismanually armed (typically by a pushbutton or equivalent)Armed means its ready to respond to a trigger. Oncethe sweep is complete, it resets, and will not sweep un-til re-armed. This mode, combined with an oscilloscope

8 1 FEATURES AND USES

camera, captures single-shot events.Types of trigger include:

external trigger, a pulse from an external source con-nected to a dedicated input on the scope.

edge trigger, an edge-detector that generates a pulsewhen the input signal crosses a specied thresholdvoltage in a specied direction. These are the most-common types of triggers; the level control sets thethreshold voltage, and the slope control selects thedirection (negative or positive-going). (The rst sen-tence of the description also applies to the inputs tosome digital logic circuits; those inputs have xedthreshold and polarity response.)

video trigger, a circuit that extracts synchronizingpulses from video formats such as PAL and NTSCand triggers the timebase on every line, a speciedline, every eld, or every frame. This circuit is typi-cally found in a waveform monitor device, althoughsome better oscilloscopes include this function.

delayed trigger, which waits a specied time after anedge trigger before starting the sweep. As describedunder delayed sweeps, a trigger delay circuit (typi-cally the main sweep) extends this delay to a knownand adjustable interval. In this way, the operator canexamine a particular pulse in a long train of pulses.

Some recent designs of oscilloscopes include more so-phisticated triggering schemes; these are described to-ward the end of this article.

1.3.6 Delayed sweeps

More sophisticated analog oscilloscopes contain a secondtimebase for a delayed sweep. A delayed sweep providesa very detailed look at some small selected portion of themain timebase. The main timebase serves as a control-lable delay, after which the delayed timebase starts. Thiscan start when the delay expires, or can be triggered (only)after the delay expires. Ordinarily, the delayed timebaseis set for a faster sweep, sometimes much faster, such as1000:1. At extreme ratios, jitter in the delays on consecu-tive main sweeps degrades the display, but delayed-sweeptriggers can overcome that.The display shows the vertical signal in one of severalmodes: the main timebase, or the delayed timebase only,or a combination thereof. When the delayed sweep isactive, the main sweep trace brightens while the delayedsweep is advancing. In one combination mode, providedonly on some oscilloscopes, the trace changes from themain sweep to the delayed sweep once the delayed sweepstarts, although less of the delayed fast sweep is visible forlonger delays. Another combination mode multiplexes(alternates) the main and delayed sweeps so that both ap-pear at once; a trace separation control displaces them.

DSOs allow waveforms to be displayed in this way, with-out oering a delayed timebase as such.

1.4 Dual and multiple-trace oscilloscopes

Oscilloscopes with two vertical inputs, referred to asdual-trace oscilloscopes, are extremely useful and com-monplace. Using a single-beam CRT, they multiplex theinputs, usually switching between them fast enough to dis-play two traces apparently at once. Less common areoscilloscopes with more traces; four inputs are commonamong these, but a few (Kikusui, for one) oered a dis-play of the sweep trigger signal if desired. Some multi-trace oscilloscopes use the external trigger input as an op-tional vertical input, and some have third and fourth chan-nels with only minimal controls. In all cases, the inputs,when independently displayed, are time-multiplexed, butdual-trace oscilloscopes often can add their inputs to dis-play a real-time analog sum. (Inverting one channel pro-vides a dierence, provided that neither channel is over-loaded. This dierence mode can provide a moderate-performance dierential input.)Switching channels can be asynchronous, that is, free-running, with trace blanking while switching, or af-ter each horizontal sweep is complete. Asynchronousswitching is usually designated Chopped, while sweep-synchronized is designated Alt[ernate]". A given chan-nel is alternately connected and disconnected, leadingto the term chopped. Multi-trace oscilloscopes alsoswitch channels either in chopped or alternate modes.In general, choppedmode is better for slower sweeps. It ispossible for the internal chopping rate to be a multiple ofthe sweep repetition rate, creating blanks in the traces, butin practice this is rarely a problem; the gaps in one traceare overwritten by traces of the following sweep. A fewoscilloscopes had a modulated chopping rate to avoid thisoccasional problem. Alternate mode, however, is betterfor faster sweeps.True dual-beam CRT oscilloscopes did exist, but werenot common. One type (Cossor, U.K.) had a beam-splitter plate in its CRT, and single-ended deection fol-lowing the splitter. Others had two complete electronguns, requiring tight control of axial (rotational) mechan-ical alignment in manufacturing the CRT. Beam-splittertypes had horizontal deection common to both verti-cal channels, but dual-gun oscilloscopes could have sep-arate time bases, or use one time base for both channels.Multiple-gun CRTs (up to ten guns) were made in pastdecades. With ten guns, the envelope (bulb) was cylin-drical throughout its length. (Also see CRT Inventionin Oscilloscope history.)

1.6 Bandwidth 9

1.5 The vertical amplier

In an analog oscilloscope, the vertical amplier acquiresthe signal[s] to be displayed. In better oscilloscopes, itdelays them by a fraction of a microsecond, and pro-vides a signal large enough to deect the CRTs beam.That deection is at least somewhat beyond the edgesof the graticule, and more typically some distance o-screen. The amplier has to have low distortion to dis-play its input accurately (it must be linear), and it has torecover quickly from overloads. As well, its time-domainresponse has to represent transients accuratelyminimalovershoot, rounding, and tilt of a at pulse top.A vertical input goes to a frequency-compensated step at-tenuator to reduce large signals to prevent overload. Theattenuator feeds a low-level stage (or a few), which in turnfeed gain stages (and a delay-line driver if there is a de-lay). Following aremore gain stages, up to the nal outputstage which develops a large signal swing (tens of volts,sometimes over 100 volts) for CRT electrostatic deec-tion.In dual and multiple-trace oscilloscopes, an internal elec-tronic switch selects the relatively low-level output of onechannels ampliers and sends it to the following stagesof the vertical amplier, which is only a single channel,so to speak, from that point on.In free-running (chopped) mode, the oscillator (whichmay be simply a dierent operating mode of the switchdriver) blanks the beam before switching, and unblanks itonly after the switching transients have settled.Part way through the amplier is a feed to the sweep trig-ger circuits, for internal triggering from the signal. Thisfeed would be from an individual channels amplier ina dual or multi-trace oscilloscope, the channel dependingupon the setting of the trigger source selector.This feed precedes the delay (if there is one), which al-lows the sweep circuit to unblank the CRT and start theforward sweep, so the CRT can show the triggering event.High-quality analog delays add a modest cost to an oscil-loscope, and are omitted in oscilloscopes that are cost-sensitive.The delay, itself, comes from a special cable with a pairof conductors wound around a exible, magnetically softcore. The coiling provides distributed inductance, whilea conductive layer close to the wires provides distributedcapacitance. The combination is a wideband transmissionline with considerable delay per unit length. Both endsof the delay cable require matched impedances to avoidreections.

1.5.1 X-Y mode

Most modern oscilloscopes have several inputs for volt-ages, and thus can be used to plot one varying voltageversus another. This is especially useful for graphing I-V

A 24-hour clock displayed on a CRT oscilloscope congured inX-Y mode as a vector monitor with dual R2R DACs to generatethe analog voltages.

curves (current versus voltage characteristics) for compo-nents such as diodes, as well Lissajous patterns. Lissajousgures are an example of how an oscilloscope can be usedto track phase dierences between multiple input signals.This is very frequently used in broadcast engineering toplot the left and right stereophonic channels, to ensurethat the stereo generator is calibrated properly. Histori-cally, stable Lissajous gures were used to show that twosine waves had a relatively simple frequency relationship,a numerically-small ratio. They also indicated phase dif-ference between two sine waves of the same frequency.TheX-Ymode also allows the oscilloscope to be used as avector monitor to display images or user interfaces. Manyearly games, such as Tennis for Two, used an oscilloscopeas an output device.[11]

Complete loss of signal in an X-Y CRT display meansthat the beam strikes a small spot, which risks burning thephosphor. Older phosphors burned more easily. Somededicated X-Y displays reduce beam current greatly, orblank the display entirely, if there are no inputs present.

1.6 Bandwidth

As with all practical instruments, oscilloscopes do not re-spond equally to all possible input frequencies. The rangeof frequencies an oscilloscope can usefully display is re-ferred to as its bandwidth. Bandwidth applies primarilyto the Y-axis, although the X-axis sweeps have to be fastenough to show the highest-frequency waveforms.The bandwidth is dened as the frequency at which thesensitivity is 0.707 of that at DC or the lowest AC fre-quency (a drop of 3 dB).[12] The oscilloscopes responsewill drop o rapidly as the input frequency is raised abovethat point. Within the stated bandwidth the response willnot necessarily be exactly uniform (or at), but shouldalways fall within a +0 to 3 dB range. One source[12]states that there is a noticeable eect on the accuracy ofvoltage measurements at only 20 percent of the statedbandwidth. Some oscilloscopes specications do include

10 2 OTHER FEATURES

a narrower tolerance range within the stated bandwidth.Probes also have bandwidth limits and must be chosenand used to properly handle the frequencies of interest.To achieve the attest response, most probes must becompensated (an adjustment performed using a test sig-nal from the oscilloscope) to allow for the reactance of theprobes cable.Another related specication is rise time. This is theduration of the fastest pulse that can be resolved by thescope. It is related to the bandwidth approximately by:Bandwidth in Hz x rise time in seconds = 0.35 [13]

For example, an oscilloscope intended to resolve pulseswith a rise time of 1 nanosecond would have a bandwidthof 350 MHz.In analog instruments, the bandwidth of the oscilloscopeis limited by the vertical ampliers and the CRT or otherdisplay subsystem. In digital instruments, the samplingrate of the analog to digital converter (ADC) is a factor,but the stated analog bandwidth (and therefore the over-all bandwidth of the instrument) is usually less than theADCs Nyquist frequency. This is due to limitations inthe analog signal amplier, deliberate design of the Anti-aliasing lter that precedes the ADC, or both.For a digital oscilloscope, a rule of thumb is that the con-tinuous sampling rate should be ten times the highest fre-quency desired to resolve; for example a 20 megasam-ple/second rate would be applicable for measuring signalsup to about 2 megahertz. This allows the anti-aliasing l-ter to be designed with a 3 dB down point of 2 MHz andan eective cuto at 10 MHz (the Nyquist frequency),avoiding the artifacts of a very steep (brick-wall) lter.A sampling oscilloscope can display signals of consider-ably higher frequency than the sampling rate if the sig-nals are exactly, or nearly, repetitive. It does this by tak-ing one sample from each successive repetition of the in-put waveform, each sample being at an increased timeinterval from the trigger event. The waveform is then dis-played from these collected samples. This mechanism isreferred to as equivalent-time sampling.[14] Some oscil-loscopes can operate in either this mode or in the moretraditional real-time mode at the operators choice.

2 Other featuresSome oscilloscopes have cursors, which are lines that canbe moved about the screen to measure the time intervalbetween two points, or the dierence between two volt-ages. A few older oscilloscopes simply brightened thetrace at movable locations. These cursors are more ac-curate than visual estimates referring to graticule lines.Better quality general purpose oscilloscopes include a cal-ibration signal for setting up the compensation of testprobes; this is (often) a 1 kHz square-wave signal of a

A computer model of the sweep of the oscilloscope

denite peak-to-peak voltage available at a test termi-nal on the front panel. Some better oscilloscopes alsohave a squared-o loop for checking and adjusting cur-rent probes.Sometimes the event that the user wants to see may onlyhappen occasionally. To catch these events, some oscil-loscopes, known as storage scopes, preserve the mostrecent sweep on the screen. This was originally achievedby using a special CRT, a "storage tube", which would re-tain the image of even a very brief event for a long time.Some digital oscilloscopes can sweep at speeds as slowas once per hour, emulating a strip chart recorder. Thatis, the signal scrolls across the screen from right to left.Most oscilloscopes with this facility switch from a sweepto a strip-chart mode at about one sweep per ten seconds.This is because otherwise, the scope looks broken: itscollecting data, but the dot cannot be seen.In current oscilloscopes, digital signal sampling is moreoften used for all but the simplest models. Samples feedfast analog-to-digital converters, following which all sig-nal processing (and storage) is digital.Many oscilloscopes have dierent plug-in modules fordierent purposes, e.g., high-sensitivity ampliers of rel-atively narrow bandwidth, dierential ampliers, ampli-ers with four or more channels, sampling plugins forrepetitive signals of very high frequency, and special-purpose plugins, including audio/ultrasonic spectrum an-alyzers, and stable-oset-voltage direct-coupled channelswith relatively high gain.

2.1 Examples of use

One of the most frequent uses of scopes istroubleshooting malfunctioning electronic equip-ment. One of the advantages of a scope is that it cangraphically show signals: where a voltmeter may show atotally unexpected voltage, a scope may reveal that thecircuit is oscillating. In other cases the precise shape ortiming of a pulse is important.In a piece of electronic equipment, for example, theconnections between stages (e.g. electronic mixers,

2.3 Selection 11

Lissajous gures on an oscilloscope, with 90 degrees phase dif-ference between x and y inputs.

electronic oscillators, ampliers) may be 'probed' for theexpected signal, using the scope as a simple signal tracer.If the expected signal is absent or incorrect, some pre-ceding stage of the electronics is not operating correctly.Since most failures occur because of a single faulty com-ponent, each measurement can prove that half of thestages of a complex piece of equipment either work, orprobably did not cause the fault.Once the faulty stage is found, further probing can usu-ally tell a skilled technician exactly which component hasfailed. Once the component is replaced, the unit can berestored to service, or at least the next fault can be iso-lated. This sort of troubleshooting is typical of radio andTV receivers, as well as audio ampliers, but can apply toquite-dierent devices such as electronic motor drives.Another use is to check newly designed circuitry. Veryoften a newly designed circuit will misbehave becauseof design errors, bad voltage levels, electrical noise etc.Digital electronics usually operate from a clock, so adual-trace scope which shows both the clock signal anda test signal dependent upon the clock is useful. Storagescopes are helpful for capturing rare electronic eventsthat cause defective operation.Pictures of use

Heterodyne AC hum on sound. Sum of a low-frequency and a high-frequency signal. Bad lter on sine. Dual trace, showing dierent time bases on eachtrace.

2.2 Automotive useFirst appearing in the 1970s for ignition system anal-ysis, automotive oscilloscopes are becoming an impor-

tant workshop tool for testing sensors and output signalson electronic engine management systems, braking andstability systems.

2.3 Selection

For work at high frequencies and with fast digital signals,the bandwidth of the vertical ampliers and sampling ratemust be high enough. For general-purpose use, a band-width of at least 100 MHz is usually satisfactory. A muchlower bandwidth is sucient for audio-frequency appli-cations only. A useful sweep range is from one secondto 100 nanoseconds, with appropriate triggering and (foranalog instruments) sweep delay. A well-designed, sta-ble trigger circuit is required for a steady display. Thechief benet of a quality oscilloscope is the quality of thetrigger circuit.Key selection criteria of a DSO (apart from input band-width) are the sample memory depth and sample rate.Early DSOs in the mid- to late 1990s only had a few KBof sample memory per channel. This is adequate for ba-sic waveform display, but does not allow detailed exami-nation of the waveform or inspection of long data pack-ets for example. Even entry-level (

12 3 TYPES AND MODELS

hand value of the instrument.As of 2007, a 350 MHz bandwidth (BW), 2.5 gigasam-ples per second (GS/s), dual-channel digital storage scopecosts about US$7000 new.On the lowest end, an inexpensive hobby-grade single-channel DSO could be purchased for under $90 as of June2011. These often have limited bandwidth and other fa-cilities, but fulll the basic functions of an oscilloscope.

2.4 SoftwareMany oscilloscopes today provide one or more externalinterfaces to allow remote instrument control by exter-nal software. These interfaces (or buses) include GPIB,Ethernet, serial port, and USB.

3 Types and modelsMain article: Oscilloscope types

The following section is a brief summary of various typesand models available. For a detailed discussion, refer tothe other article.

3.1 Cathode-ray oscilloscope (CRO)For more details on this topic, see Oscilloscope types Cathode-ray oscilloscope.The earliest and simplest type of oscilloscope consisted

Example of an analog oscilloscope Lissajous gure, showing aharmonic relationship of 1 horizontal oscillation cycle to 3 verti-cal oscillation cycles.

of a cathode ray tube, a vertical amplier, a timebase, ahorizontal amplier and a power supply. These are nowcalled analog scopes to distinguish them from the digi-tal scopes that became common in the 1990s and 2000s.Analog scopes do not necessarily include a calibrated ref-erence grid for size measurement of waves, and they may

For analog television, an analog oscilloscope can be used as avectorscope to analyze complex signal properties, such as this dis-play of SMPTE color bars.

not display waves in the traditional sense of a line segmentsweeping from left to right. Instead, they could be usedfor signal analysis by feeding a reference signal into oneaxis and the signal to measure into the other axis. For anoscillating reference and measurement signal, this resultsin a complex looping pattern referred to as a Lissajouscurve. The shape of the curve can be interpreted to iden-tify properties of the measurement signal in relation tothe reference signal, and is useful across a wide range ofoscillation frequencies.

3.2 Dual-beam oscilloscope

The dual-beam analog oscilloscope can display two sig-nals simultaneously. A special dual-beam CRT generatesand deects two separate beams. Although multi-traceanalog oscilloscopes can simulate a dual-beam displaywith chop and alternate sweeps, those features do notprovide simultaneous displays. (Real time digital oscil-loscopes oer the same benets of a dual-beam oscillo-scope, but they do not require a dual-beam display.) Thedisadvantages of the dual trace oscilloscope are that itcannot switch quickly between the traces and it cannotcapture two fast transient events. In order to avoid thisproblems a dual beam oscilloscope is used.

3.3 Analog storage oscilloscope

For more details on this topic, see Cathode ray tube Oscilloscope CRTs.For more details on this topic, see Oscilloscope types Analog storage oscilloscope.

Trace storage is an extra feature available on some ana-log scopes; they used direct-view storage CRTs. Storageallows the trace pattern that normally decays in a fractionof a second to remain on the screen for several minutesor longer. An electrical circuit can then be deliberatelyactivated to store and erase the trace on the screen.

3.6 Mixed-domain oscilloscopes 13

3.4 Digital oscilloscopes

Main article: Digital storage oscilloscope

While analog devices make use of continually varyingvoltages, digital devices employ binary numbers whichcorrespond to samples of the voltage. In the case of digi-tal oscilloscopes, an analog-to-digital converter (ADC) isused to change the measured voltages into digital infor-mation.

A Siglent SDS1000 Series Oscilloscope. A modern low cost DSO.

The digital storage oscilloscope, or DSO for short, is nowthe preferred type for most industrial applications, al-though simple analog CROs are still used by hobbyists.It replaces the electrostatic storage method used in ana-log storage scopes with digital memory, which can storedata as long as required without degradation and with uni-form brightness. It also allows complex processing of thesignal by high-speed digital signal processing circuits.[3]

A standard DSO is limited to capturing signals with abandwidth of less than half the sampling rate of the ADC(called the Nyquist limit). There is a variation of the DSOcalled the digital sampling oscilloscope that can exceedthis limit for certain types of signal, such as high-speedcommunications signals, where the waveform consists ofrepeating pulses. This type of DSO deliberately samplesat a much lower frequency than the Nyquist limit and thenuses signal processing to reconstruct a composite view ofa typical pulse. A similar technique, with analog ratherthan digital samples, was used before the digital era inanalog sampling oscilloscopes.[17][18]

A digital phosphor oscilloscope (DPO) uses color infor-mation to convey information about a signal. It may, forexample, display infrequent signal data in blue to makeit stand out. In a conventional analog scope, such a raretrace may not be visible.

3.5 Mixed-signal oscilloscopes

A mixed-signal oscilloscope (or MSO) has two kindsof inputs, a small number of analog channels (typi-cally two or four), and a larger number of digital chan-nels(typically sixteen). It provides the ability to accu-rately time-correlate analog and digital channels, thus of-fering a distinct advantage over a separate oscilloscope

and logic analyser. Typically, digital channels may begrouped and displayed as a bus with each bus value dis-played at the bottom of the display in hex or binary. Onmost MSOs, the trigger can be set across both analog anddigital channels.

3.6 Mixed-domain oscilloscopes

In a mixed-domain oscilloscope (MDO) you have an ad-ditional RF input port that goes into a spectrum analyzerpart. It links those traditionally separate instruments, sothat you can e.g. time correlate events in the time domain(like a specic serial data package) with events happeningin the frequency domain (like RF transmissions).

3.7 Handheld oscilloscopes

Siglent Handheld Oscilloscope SHS800 Series

For more details on this topic, see Oscilloscope types Handheld oscilloscopes.

Handheld oscilloscopes are useful for many test and eldservice applications. Today, a hand held oscilloscopeis usually a digital sampling oscilloscope, using a liquidcrystal display.Many hand-held and bench oscilloscopes have the groundreference voltage common to all input channels. If morethan one measurement channel is used at the same time,all the input signals must have the same voltage refer-ence, and the shared default reference is the earth. Ifthere is no dierential preamplier or external signal iso-lator, this traditional desktop oscilloscope is not suitablefor oating measurements. (Occasionally an oscilloscopeuser will break the ground pin in the power supply cord ofa bench-top oscilloscope in an attempt to isolate the signal

14 5 SEE ALSO

common from the earth ground. This practice is unreli-able since the entire stray capacitance of the instrumentcabinet will be connected into the circuit. Since it is alsoa hazard to break a safety ground connection, instructionmanuals strongly advise against this practice.)

Siglent Isolation Oscilloscope SHS1000 Series

Some models of oscilloscope have isolated inputs, wherethe signal reference level terminals are not connected to-gether. Each input channel can be used to make a oat-ing measurement with an independent signal referencelevel. Measurements can be made without tying one sideof the oscilloscope input to the circuit signal common orground reference.The isolation available is categorized as shown below:

3.8 PC-based oscilloscopes

PicoScope 6000 digital PC-based oscilloscope using a laptopcomputer for display & processing

For more details on this topic, see Oscilloscope types PC-based oscilloscopes.

A new type of oscilloscope is emerging that consists of aspecialized signal acquisition board (which can be an ex-ternal USB or parallel port device, or an internal add-onPCI or ISA card). The user interface and signal process-ing software runs on the users computer, rather than onan embedded computer as in the case of a conventionalDSO.

3.9 Related instruments

A large number of instruments used in a variety of tech-nical elds are really oscilloscopes with inputs, calibra-tion, controls, display calibration, etc., specialized andoptimized for a particular application. Examples ofsuch oscilloscope-based instruments include waveformmonitors for analyzing video levels in television produc-tions and medical devices such as vital function monitorsand electrocardiogram and electroencephalogram instru-ments. In automobile repair, an ignition analyzer is usedto show the spark waveforms for each cylinder. All ofthese are essentially oscilloscopes, performing the basictask of showing the changes in one or more input signalsover time in an XY display.Other instruments convert the results of their measure-ments to a repetitive electrical signal, and incorporate anoscilloscope as a display element. Such complex mea-surement systems include spectrum analyzers, transistoranalyzers, and time domain reectometers (TDRs). Un-like an oscilloscope, these instruments automatically gen-erate stimulus or sweep a measurement parameter.

4 HistoryMain article: Oscilloscope history

The Braun tube was known in 1897, and in 1899 JonathanZenneck equipped it with beam-forming plates and amagnetic eld for sweeping the trace. Early cathode raytubes had been applied experimentally to laboratory mea-surements as early as the 1920s, but suered from poorstability of the vacuum and the cathode emitters. V. K.Zworykin described a permanently sealed, high-vacuumcathode ray tube with a thermionic emitter in 1931. Thisstable and reproducible component allowed General Ra-dio to manufacture an oscilloscope that was usable out-side a laboratory setting.[3] After World War II surpluselectronic parts became the basis of revival of HeathkitCorporation, and a $50 oscilloscope kit made from suchparts was a rst market success.

5 See also Eye pattern

15

Phonodeik Tennis for Two, an oscilloscope game Time-domain reectometry Vectorscope Waveform monitor

6 References[1] How the Cathode Ray Oscillograph Is Used in Radio Ser-

vicing, National Radio Institute (1943)

[2] Cathode-Ray Oscillograph 274A Equipment DuMontLabs, Allen B (in German). Radiomuseum.org. Re-trieved 2014-03-15.

[3] Kularatna, Nihal (2003), Fundamentals of Oscillo-scopes, Digital and Analogue Instrumentation: Testingand Measurement, Institution of Engineering and Tech-nology, pp. 165208, ISBN 978-0-85296-999-1

[4] The 20 picofarad value is typical for scope bandwidthsaround 100 MHz; for example, a 200 MHz Tektronix7A26 input impedance is 1M and 22 pF. (Tektronix(1983, p. 271); see also Tektronix (1998, p. 503), typ-ical high Z 10X passive probe model.) Lower band-width scopes used higher capacitances; the 1 MHz Tek-tronix 7A22 input impedance is 1M and 47 pF. (Tektronix1983, pp. 272273) Higher bandwidth scopes use smallercapacitances. The 500 MHz Tektronix TDS510A inputimpedance is 1M and 10 pF. (Tektronix 1998, p. 78)

[5] Probes are designed for a specic input impedance. Theyhave compensation adjustments with a limited range, sothey often cannot be used on dierent input impedances.

[6] Wedlock & Roberge (1969)

[7] Kobbe & Polits (1959)

[8] Tektronix (1983, p. 426); Tek claims 300 MHz resistivecoax at 30 pF per meter; schematic has 5 adjustments.

[9] Zeidlhack & White (1970)

[10] Jones, David. Oscilloscope Trigger Holdo Tutorial.EEVblog. Retrieved 30 December 2012.

[11] Nosowitz, Dan (2008-11-08). "'Tennis for Two',the Worlds First Graphical Videogame. Retromodo.Gizmodo. Retrieved 2008-11-09.

[12] Webster, John G. (1999). The Measurement, Instrumenta-tion and Sensors Handbook (illustrated ed.). Springer. p.37-24. ISBN 978-3540648307.

[13] Spitzer, Frank; Howarth, Barry (1972), Principles of mod-ern Instrumentation, New York: Holt, Rinehart and Win-ston, p. 119, ISBN 0-03-080208-3

[14] http://literature.cdn.keysight.com/litweb/pdf/5989-8794EN.pdf

[15] Jones, David. DSO Tutorial. EEVblog. Retrieved 30December 2012.

[16] Minimum Required Sample Rate (PDF). Agilent. Re-trieved 30 December 2012.

[17] Sampling Oscilloscope Techniques (PDF), Tektronix,1989, Technique Primer 47W-7209, retrieved 11 Octo-ber 2012, In 1960 Tektronix made it possible to measuresignals over 100 MHz with the introduction of the rstanalog sampling oscilloscope.

[18] Green, Leslie (June 21, 2001), The alias theorems: prac-tical undersampling for expert engineers, EDN, retrieved11 October 2012

US 2883619, Kobbe, John R. & William J. Polits,Electrical Probe, issued April 21, 1959

Tektronix (1983), Tek Products, Tektronix Tektronix (1998), Measurement Products Catalog

1998/1999, Tektronix

Wedlock, Bruce D.; Roberge, James K. (1969),Electronic Components and Measurements, Prentice-Hall, pp. 150152, ISBN 0-13-250464-2

US 3532982, Zeidlhack, Donald F. & Richard K.White, Transmission Line Termination Circuit,issued October 6, 1970

7 External links XYZ of Oscilloscopes, Tektronix, 64 page Tutorial Open Source Physics Oscilloscope Model Oscilloscope Fundamentals Primer, Rohde &Schwarz

Using an Oscilloscope Oscilloscope basic guide Oscilloscope tutorial videos Digital Storage Oscilloscope measurement basics Low Cost Oscilloscope, Utilizing TRS Connector(3.5 mm Jack)

Oscilloscope Development, 1943-1957 The Cathode Ray Tube site Oscilloscope History and Development Milestones,1890-today

16 8 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

8 Text and image sources, contributors, and licenses8.1 Text

Oscilloscope Source: https://en.wikipedia.org/wiki/Oscilloscope?oldid=670491958 Contributors: AxelBoldt, Bryan Derksen, Andre En-gels, PierreAbbat, MauryMarkowitz, Heron, Hfastedge, Patrick, RTC,Michael Hardy, Tim Starling, Collabi, Theresa knott, AugPi, Andres,Tantalate, RickK, Dmsar, Reddi, Andrewman327, Colin Marquardt, Radiojon, Furrykef, Hyacinth, Omegatron, Wernher, Raul654, Denel-son83, Maheshkale, EpiVictor, Robbot, Ktims, Hadal, Victor, Cyrius, Giftlite, DavidCary, Mat-C, Mintleaf~enwiki, Freddybaby, Micru,AJim, Aechols, Tipiac, Chowbok, Antandrus, OverlordQ, Alkivar, Zowie, Discospinster, Rama, YUL89YYZ, Jantangring, Aaronbrick,Bobo192, Longhair, Cmacd123, Giraedata, Hooperbloob, Patrick Bernier, Arthena, Atlant, RoySmith, Nasukaren, BryanD, Metron4,Wtshymanski, Gene Nygaard, Kenyon, Postrach, Dr Gangrene, RHaworth, Brazil4Linux, David Haslam, Drichards2, Pol098, The Word-smith, Rtdrury, Ch'marr, GregorB, Isnow, Bruns, Qwertyus, Vanderdecken, Rjwilmsi, Strait, PHenry, Tawker, ElKevbo, Alll~enwiki,Krash, Matt Deres, Johnrpenner, Arnero, RobyWayne, Wongm, Lmatt, Terrx, Srleer, Chobot, Krishnavedala, Gwernol, Cornellrockey,YurikBot, Hairy Dude, RussBot, DMahalko, Rocketgoat, Pburka, Rada, Hydrargyrum, Eddie.willers, Grafen, Rickyboy, Natkeeran, Is-landGyrl, DeadEyeArrow, Psy guy, Jeh, Morpheios Melas, Dna-webmaster, Light current, Where next Columbus?, Tevildo, Mike1024,CWenger, Shyam, Nelson50, Katieh5584, Bernd in Japan, TuukkaH, SmackBot, Apina~enwiki, Reedy, InverseHypercube, Unyoyega,Tex23, Betacommand, KD5TVI, Bluebot, Nikhilele, Keegan, MK8, Master of Puppets, Thumperward, Oli Filth, MalafayaBot, Nbarth,Dual Freq, Javalenok, Can't sleep, clown will eat me, RyanEberhart, Frap, HeavyD14, Spectrogram, Mike1305, S Roper, HarisM, Sbluen,Adrigon, Tehw1k1, Pasmwaly, Autopilot, SashatoBot, KLLvr283, Hefo~enwiki, Butko, MonstaPro, Fernando S. Aldado~enwiki, CyrilB,TastyPoutine, Odedee, Kbisking, StephenBuxton, NETTKNUT, CapitalR, Flickboy, Wiltors, Alexv7255, CmdrObot, Yinchongding,Nczempin, Requestion, Michael B. Trausch, Theguru320, Funnyfarmofdoom, Fl295, Phatom87, Jetblack101, Michaelas10, Zomic13,Thijs!bot, Joeyhagedorn, Electron9, FourBlades, I already forgot, Malvineous, Bm gub, Alphachimpbot, JAnDbot, CosineKitty, Bong-warrior, VoABot II, Cmiyc, Nikevich, Indon, KumgPhil, DerHexer, Waninge, I B Wright, Cocytus, Read-write-services, Jim.henderson,Glrx, MrPCO, CommonsDelinker, Sbogdanov, Cullen kasunic, Kudpung, Drink Bottle, Tetonca, Trumpet marietta 45750, Mike Sorensen,Imrandhillon, Laichh, Joshmt, Cometstyles, Marthein, 1bigdork, Mark.klimek, Szeltman, Lights, VolkovBot, JohnBlackburne, Alexandria,The Original Wildbear, Chreer, Kipb9, Rei-bot, Anna Lincoln, Jackfork, Cuddlyable3, Jimnoid, Andy Dingley, Submitwiki, Burntsauce,Spinningspark, Nibios, Dkrennin, Monty845, Reedie2be, EmxBot, Elborgo, SieBot, Scarian, AlphaPyro, Da Joe, Jerey Zimmerman,A. Carty, Yerpo, Crowstar, Belda, Xe7al, Tombomp, Ks0stm, Marulas~enwiki, Anchor Link Bot, Smplind, Denisarona, ImageRe-movalBot, Jacob Myers, Martarius, ClueBot, PipepBot, DragonKilla, The Thing That Should Not Be, Roye82, GreenSpigot, Mild BillHiccup, Regibox, NovaDog, Niceguyedc, Hwyengineer47, DragonBot, Mumiemonstret, Rubin joseph 10, Sun Creator, QASIMARA,Thingg, Rippey574, Adtmatt, Lambtron, Johnuniq, XLinkBot, BodhisattvaBot, Cmr08, Dsimic, Addbot, Mortense, Jncraton, ProperFrac-tion, Glane23, LinkFA-Bot, Peti610botH, BakedBeanUK, Tide rolls, Lightbot, OlEnglish, Zorrobot, Softy, Luckas-bot, Yobot, Them-fromspace, QueenCake, KamikazeBot, Wonder, AnomieBOT, Jim1138, Tucoxn, Piano non troppo, AdjustShift, EryZ, Bluerasberry,Materialscientist, Agentforte, ArthurBot, LilHelpa, Capricorn42, TuomasHall, Anon423, Ocgreg, Microlm, Hpmemproject, Nedim Ar-doa, Grantmidnight, Bryawn, Wikihitech, Schekinov Alexey Victorovich, Pa7xg, Prari, Lookang, Febert, Smurfettekla, Berrinkursun,Anitauky, Haeinous, Pinethicket, Vicenarian, 10metreh, SpaceFlight89, TankTrivia, FoxBot, Mjs1991, Sintau.tayua, LuciusMare, Meanas custard, Ziniadas, Becritical, Salvio giuliano, Vishalbanty, EmausBot, John of Reading, Brian S. Elliott, Cragtech, Pipiru22, Heymid,Niluop, Jacquelinereneelewis, Wikipelli, , John Cline, Dolovis, Andyman1125, Cziomek, Caspertheghost, Demiurge1000,Warthogman133244, Rcsprinter123, Sbmeirow, ChuispastonBot, ClueBot NG, Jack Greenmaven, Satellizer, Crtcollector, P.croaker,DieSwartzPunkt, Muon, Widr, JordoCo, Theopolisme, Hxh9, Bhensley2010, Mikei520, Jagrutirk, Phyo WP, Shaun, BattyBot, Jcsjcsjcs,Pratyya Ghosh, ChrisGualtieri, Mediran, Khazar2, Ajv39, SoledadKabocha, Saehry, TwoTwoHello, Tuomasberghall, Abdd0e77, Shailen-dra10794, PantherLeapord, Daniel.bogdano, Binarysequence, PhantomTech, Richpike, Pankaj Warule, Sadashivakamath, Alicewuu,DisgustedPete, Lea-garv, Adirlanz, Mmpozulp, JAFfacake57, NQ, HenryWortel, A2850503011, BoldEditor, Kaufmanitay, Krelcoyne,Scopesinfo, KasparBot and Anonymous: 530

8.2 Images File:CROdual.gif Source: https://upload.wikimedia.org/wikipedia/commons/0/08/CROdual.gif License: CC BY-SA 4.0 Contributors:

Own workhttp://weelookang.blogspot.sg/2015/06/ejss-cathode-ray-oscilloscope-cro.html Original artist: Lookang many thanks to authorof original simulation = Fu-Kwun Hwang author of Easy Java Simulation = Francisco Esquembre

File:CROsweep.gif Source: https://upload.wikimedia.org/wikipedia/commons/a/a2/CROsweep.gif License: CC BY-SA 4.0 Contributors:Own workhttp://weelookang.blogspot.sg/2015/06/ejss-cathode-ray-oscilloscope-cro.html Original artist: Lookang many thanks to authorof original simulation = Fu-Kwun Hwang author of Easy Java Simulation = Francisco Esquembre

File:CROtperdivisionincrease.gif Source: https://upload.wikimedia.org/wikipedia/commons/0/0d/CROtperdivisionincrease.gif Li-cense: CC BY-SA 4.0 Contributors: Own workhttp://weelookang.blogspot.sg/2015/06/ejss-cathode-ray-oscilloscope-cro.html Originalartist: Lookang many thanks to author of original simulation = Fu-Kwun Hwang author of Easy Java Simulation = Francisco Esquembre

File:CROxoffset.gif Source: https://upload.wikimedia.org/wikipedia/commons/6/67/CROxoffset.gif License: CC BY-SA 4.0 Contrib-utors: Own workhttp://weelookang.blogspot.sg/2015/06/ejss-cathode-ray-oscilloscope-cro.html Original artist: Lookang many thanks toauthor of original simulation = Fu-Kwun Hwang author of Easy Java Simulation = Francisco Esquembre

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Features and usesDescriptionSize and portabilityInputsProbes

Front panel controlsFocus controlIntensity controlAstigmatismBeam finderGraticuleTimebase controlsHoldoff controlVertical sensitivity, coupling, and polarity controlsHorizontal sensitivity controlVertical position controlHorizontal position controlDual-trace controlsDelayed-sweep controlsSweep trigger controls

Basic types of sweepTriggered sweepHoldoffAutomatic sweep modeRecurrent sweepsSingle sweepsDelayed sweeps

Dual and multiple-trace oscilloscopesThe vertical amplifierX-Y mode

Bandwidth

Other featuresExamples of useAutomotive useSelectionSoftware

Types and modelsCathode-ray oscilloscope (CRO)Dual-beam oscilloscope Analog storage oscilloscopeDigital oscilloscopesMixed-signal oscilloscopesMixed-domain oscilloscopesHandheld oscilloscopesPC-based oscilloscopesRelated instruments

HistorySee alsoReferencesExternal linksText and image sources, contributors, and licensesTextImagesContent license