How to Choose an Oscilloscope

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Accurate reconstruction of a signal depends on both the sample rate and the interpolation method used.

Linear interpolation connects sample points with straight edged signals.

Sin x/x interpolation is a mathematical process in which points are calculated to fill in the time between the real samples.
This form of interpolation lends itself to curved and irregular signal shaples, which are far more common in the real world
than pure square waves and pulses.

Consequently, sin x/x interpolation is the preferred method for applications where the sample rate is 3 to 5 times the
system bandwidth.

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Versatile Triggering

Triggering gives a stable display and lets you zero in on specific parts of complex waveforms.

To acquire anomalies and make best use of the record length of scope, look for a scope that
provides advanced triggering on more challenging signals. Triggering lets you isolate a group of
waveforms to see what is going wrong. Specialized triggers can respond to specific conditions
in the incoming signal making it easy to detect, for example, a pulse that is narrower than it
should be.

The wider the range of trigger options available the more versatile the scope and the faster you
get to the root cause of a problem.

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Triggering synchronizes the horizontal sweep at the correct point in the signal,
rather than just starting the next trace at the point where the present trace
happens to finish. A single trigger acquires all input channels simultaneously.

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Long Record Length
Record lenth is the number of points in a complete waveform record.
An oscilloscope can store only a limited number of samples, so, generally
the greater the record length the better.

To search for infrequent transients such as jitter, runt pulses and glitches,
select at least a mid-end oscilloscope that conbines long record length
with a  high waveform capture rate.

WisdomAugust

Since an oscilloscope can store only a limited number of samples,
the waveform duration (time) will be inversely proportional to
the oscilloscope's sample rate.
Time interval=Record Lengh/Sample Rate

So, with a record length of 1Mpoints and sample rate of 250 MSa/s,
the oscilloscope will capture a signal 4 ms in length.

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Waveform navigation and analysis

You need following tools that automate the process and accelerate the time to search for specific waveform errors.

*Zoom and Pan allows you to zoom in on an event of interest, and pan the area backwards and forwards in time.
*Play and Pause automatically pans the zoom window across the waveform. That allows hands-free playback so you
can concentrate on what's important-the waveform itself.
*Marks let you mark events of interest while you're looking for a problem. You can use front panel controls to rapidly
jump between each mark for quick and easy timing measurements.
*Search and Mark lets you search through the entire acquisition and automatically mark every occurrence of a user-
soecified event.
*Advanced search lets you define varous different criteria, similar to trigger conditions, which will be automatically
detected and marked in the captured waveform.

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Oscilloscopes with record lengths in the millions of points can show
thousands of screens worth of signal activity, essential for examining
complex waveforms. Placing marks on the waveform assists in
latency measurements on a CAN bus, for instance.

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Automated Waveform Measurements

Automated waveform measurements make it easier to obtain accurate numerical readings.

Most oscilloscopes offer front panel buttons and/or screen based menus to take accurate automated measurements.
Basic choices on most oscilloscopes include amplitude, period and rise and fall time.
Many digital oscilloscopes also provides mean and RMS calculations, duty cycle, and other maths operations.
Advanced mathematics functions are found on some oscilloscopes, improving the time to answer even further.
e.g.
* FFT, Integrate, Differentiate, Logarithm, Exponent, Square root, Absolute
*Sine, Cosine, Tangent, Radians, Degrees
*Scalars, with user adjustable variables and results of parametric measurements.

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Automated measurements appear as on-screen alphanumeric readouts,
and are more accurate than direct graticule interpretation.

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Advanced Application

Advanced oscilloscopes have application software for optical and electrical design troubleshooting and standards compliance.

* Signal integrity and jitter measurement packages: provide insight into signal integrity-related problems is digital systems, their
causes, characteristics and effects.
*Power measurement: automated measurements for power quality, switching loss, harmonics, safe operating area, modulation,
ripple, slew rate and more.
*Support for debug of embedded systems with mixed analogy and digital, parallel and serial technologies such as CAN/LIN, I2C,
SPI, FlexRay, MOST and others.
*RF apllications: view signals in the frequency domain and analyze using spectrograms, amplitude, frequency and phase versus
time traces.
*Education: electrical engineering students need to understand complex circuits and electronic designs to develop next generation
technologies.
*Others include optical communications, memory system verification, communications standards testing, disk drive measurements,
video measurements, and more.