How does oscilloscope operate

Try fiddling with the horizontal and vertical system knobs to maneuver the waveform around the screen. Rotating the scale knobs clockwise will "zoom into" your waveform, and counter-clockwise zooms out.

You can also use the position knob to further locate your waveform. If your wave is still unstable, try rotating the trigger position knob. Make sure the trigger isn't higher than the tallest peak of your waveform. By default, the trigger type should be set to edge, which is usually a good choice for square waves like this. If your probe is set to 10X, and you don't have a perfectly square waveform as shown above, you may need to compensate your probe.

Most probes have a recessed screw head, which you can rotate to adjust the shunt capacitance of the probe. Try using a small screwdriver to rotate this trimmer, and look at what happens to the waveform. Adjust the trimming cap on the probe handle until you have a straight-edged square wave. Compensation is only necessary if your probe is attenuated e. Once you've compensated your probe, it's time to measure a real signal! Go find a signal source frequency generator? The first key to probing a signal is finding a solid, reliable grounding point.

Clasp your ground clip to a known ground, sometimes you may have to use a small wire to intermediate between the ground clip and your circuit's ground point. Then connect your probe tip to the signal under test. Probe tips exist in a variety of form factors -- the spring-loaded clip, fine point, hooks, etc. Once your signal is on the screen, you may want to begin by adjusting the horizontal and vertical scales into at least the "ballpark" of your signal.

If part of your wave is rising or falling of the screen, you can adjust the vertical position to move it up or down. If your signal is purely DC, you may want to adjust the 0V level near the bottom of your display.

Once you have the scales ballparked, your waveform may need some triggering. Edge triggering -- where the scope tries to begin its scan when it sees voltage rise or fall past a set point -- is the easiest type to use. Using an edge trigger, try to set the trigger level to a point on your waveform that only sees a rising edge once per period.

Now just scale, position, trigger and repeat until you're looking at exactly what you need. With a signal scoped, triggered, and scaled, it comes time to measure transients, periods, and other waveform properties. Some scopes have more measurement tools than others, but they'll all at least have divisions, from which you should be able to at least estimate the amplitude and frequency.

Many scopes support a variety of automatic measurement tools, they may even constantly display the most relevant information, like frequency. To get the most out of your scope, you'll want to explore all of the measure functions it supports. Most scopes will calculate frequency, amplitude, duty cycle, mean voltage, and a variety of other wave characteristics for you automatically. A third measuring tool many scopes provide is cursors. Cursors are on-screen, movable markers which can be placed on either the time or voltage axis.

Cursors usually come in pairs, so you can measure the difference between one and the other. Measuring the ringing of a square wave with cursors. Once you've measured the quantity you were looking for, you can begin to make adjustments to your circuit and measure some more!

Some scopes also support saving , printing , or storing a waveform, so you can recall it and remember those good ol' times when you scoped that signal. Now that you've learned all about this handy tool's features and benefits, it's time to put an oscilloscope on your workbench.

See our Engineering Essentials page for a full list of cornerstone topics surrounding electrical engineering.

Take me there! With the tools discussed in this tutorial, you should be prepared to start scoping signals of your own.

If you're still unsure of what certain parts of your scope are for, first consult your user's manual. Here are some additional resources we recommend checking out as well:.

Now that you're a practiced oscilloscop-er, what circuit are you going to be debugging? Need some inspiration? Here are some related tutorials we'd recommend checking out next! Need Help? Mountain Time: Shopping Cart 0 items. Product Menu. Today's Deals Forum Desktop Site. All Categories. Development Single Board Comp.

Contributors: jimblom. Introduction Have you ever found yourself troubleshooting a circuit, needing more information than a simple multimeter can provide?

Favorited Favorite 50 Wish List. Favorited Favorite 49 Wish List. Favorited Favorite 3 Wish List. HAMlab - 10W Only 3 left! Favorited Favorite 11 Wish List. Basics of O-Scopes The main purpose of an oscilloscope is to graph an electrical signal as it varies over time. Oscilloscope Lexicon Learning how to use an oscilloscope means being introduced to an entire lexicon of terms. Key Oscilloscope Specifications Some scopes are better than others. These characteristics help define how well you might expect a scope to perform: Bandwidth -- Oscilloscopes are most commonly used to measure waveforms which have a defined frequency.

No scope is perfect though: they all have limits as to how fast they can see a signal change. The bandwidth of a scope specifies the range of frequencies it can reliably measure.

Digital vs. Analog -- As with most everything electronic, o-scopes can either be analog or digital. Analog scopes use an electron beam to directly map the input voltage to a display. Digital scopes incorporate microcontrollers, which sample the input signal with an analog-to-digital converter and map that reading to the display. Generally analog scopes are older, have a lower bandwidth, and less features, but they may have a faster response and look much cooler.

Channel Amount -- Many scopes can read more than one signal at a time, displaying them all on the screen simultaneously. Each signal read by a scope is fed into a separate channel. Two to four channel scopes are very common. Sampling Rate -- This characteristic is unique to digital scopes, it defines how many times per second a signal is read. For scopes that have more than one channel, this value may decrease if multiple channels are in use. The sample points from the ADC are stored in memory as waveform points.

More than one sample point may make up one waveform point. Together, the waveform points make up one waveform record. The number of waveform points used to make a waveform record is called the record length.

The trigger system determines the start and stop points of the record. The display receives these record points after being stored in memory. Depending on the capabilities of your oscilloscope, additional processing of the sample points may take place, enhancing the display. Pretrigger may be available, allowing you to see events before the trigger point. Fundamentally, with a digital oscilloscope as with an analog oscilloscope, you need to adjust the vertical, horizontal, and trigger settings to take a measurement.

Sampling Methods. The sampling method tells the digital oscilloscope how to collect sample points. For slowly changing signals, a digital oscilloscope easily collects more than enough sample points to construct an accurate picture. However, for faster signals, how fast depends on the oscilloscope's maximum sample rate the oscilloscope cannot collect enough samples.

The digital oscilloscope can do two things:. Real-Time Sampling with Interpolation. Digital oscilloscopes use real-time sampling as the standard sampling method. In real-time sampling, the oscilloscope collects as many samples as it can as the signal occurs.

See following figure for single-shot or transient signals you must use real time sampling. Digital oscilloscopes use interpolation to display signals that are so fast that the oscilloscope can only collect a few sample points.

Interpolation "connects the dots. Linear interpolation simply connects sample points with straight lines. Sine interpolation or sin x over x interpolation connects sample points with curves. See Following Figure Sin x over x interpolation is a mathematical process similar to the "oversampling" used in compact disc players.

With sine interpolation, points are calculated to fill in the time between the real samples. Using this process, a signal that is sampled only a few times in each cycle can be accurately displayed or, in the case of the compact disc player, accurately played back.

Now your hand is strapped to two electric motors, both of which are in turn connected to electronic circuits that can test signals of different kinds. Moreover, one of the motors can move your hand in a vertical y direction, even as the other moves the hand in the horizontal x direction. Now say, we connect the x-circuit to an electronic quartz clock. So when the clock ticks, it sends a signal to the x motor thus moving your hand to the right, thereby making you draw a horizontal line.

With the x and y circuits connected at the same time, your hand will move across the page, but it will jump up vertically each time the heart beats.

This, in effect, is what happens in an oscilloscope too; except the pencil is the electronic beam and the graph paper is the screen. Oscilloscopes are used in several fields today - be it sciences, medicine, engineering, automotive or the telecommunications industry. General-purpose oscilloscopes are used for maintenance of electronic equipment and laboratory work. For instance, within radio frequency RF design, general electronics circuit design, electronics manufacturing, service, repair or an area where electronic circuits and the waveforms on them have to be observed.

In fact, troubleshooting with an oscilloscope is a common and rather reliable method for analyzing modern electronic circuitry.

Special-purpose oscilloscopes, as the name suggests, are used with a specific aim in mind, say, displaying the waveform of the heartbeat as an electrocardiogram or analyzing an automotive ignition system. Oscilloscopes can be bought from Tektronix, a leading manufacturer of test and measurement devices including oscilloscopes, logic analyzers, and video and mobile test equipment.

Tektronix also provides oscilloscope calibration services. Engineering : Electronic, sound and computer design engineering rely heavily on oscilloscopes -be it carrying out complicated measurements or tracking sound and engine vibrations.

Electronics : Electronic technicians, including those who service and repair household and business electronics such as televisions, computers, and audio video systems, use oscilloscopes for testing equipment, parts and assemblies in these devices.

Healthcare : Oscilloscopes are used as medical measuring instruments; especially to check for heart irregularities. Sciences Physics : Oscilloscopes are extensively used for diagnosis in the scientific community, and enjoy greater demand from physicists who tend to regularly use them for several applications.

Vehicle Repair : Mechanics use oscilloscopes to test fuel injectors or to examine and repair a car in a no-start condition.

This is the earliest and simplest type of oscilloscope that was made up of a cathode ray tube, a vertical amplifier, a timebase, a horizontal amplifier and a power supply. Now referred to as analog oscilloscopes to distinguish them from the digital ones that shot to popularity in the s, these CROs do not always include a calibrated reference grid for size measurement of waves, and they may not show waves in the conventional sense of a line segment sweeping from left to right.

But they could be used for signal analysis by putting a reference signal into one axis and the signal to measure into the other axis. The dual-beam analog oscilloscope can send out two signals at the same time. A special dual-beam CRT produces and deflects the two different beams. A dual-trace analog oscilloscope can simulate a dual-beam display with chop and alternate sweeps, but simultaneous displays are still lacking here.

This is where a dual-beam oscilloscope fares better: unlike the dual trace oscilloscope, it can switch quickly between traces, and capture two fast transient events. Trace storage is the extra feature in these oscilloscopes that dwell on the use of direct-view storage CRTs. Storage allows the trace pattern to stay on the screen for several minutes as opposed to a fraction of a second. Here the analog-to-digital converter ADC measures the voltages and converts into digital information.

The digital storage oscilloscope, or DSO for short, is the standard oscilloscope model used today in several industrial applications, and even by hobbyists due to the low costs of entry-level oscilloscopes. Digital memory comes into play here and sample data is stored for as long as needed without worries about degradation and or the brightness issue one faces with storage-type CRTs. A DSO also makes possible the complex processing of the signal by high-speed digital signal processing circuits.

The two key specs of a digital scope are its analog bandwidth and its sampling rate or sample rate. While the analog bandwidth helps determine if we can accurately measure a signal with a given frequency, a sample rate is the number of samples an oscilloscope can acquire per second. If the sample rate is not fast enough, one will not be able to see the signal accurately on the oscilloscope screen. So the resolution of the waveform depends on the sample rate.

A mixed-signal oscilloscope MSO has two kinds of inputs, a small number of analog channels , and a greater number of digital channels usually It can accurately time-correlate analog and digital channels.