How to Choose an Oscilloscope

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1 Consider the bandwidth range.

Depending on what you use the oscilloscope for, the range of the bandwidth it can process should be the primary consideration.

Remember that the bandwidth specification of an oscilloscope is the frequency of the "-3 dB point" of a sine-wave signal of a particular amplitude, e.g. 1 Vpp. As the frequency of your sinewave goes up (while keeping the amplitude constant), the measured amplitude goes down. The frequency at which this amplitude is -3 dB lower, is the instrument's bandwidth. This means that an oscilloscope of 100MHz would measure a 1Vpp sinewave of 100MHz at only (approx.) 0.7Vpp. That is an error of about 30%! In order to measure more correctly, use this rule of thumb: BW/3 equals about 5% error; BW/5 equals about 3% error.

In other words: if the highest frequency you want to measure is 100 MHz, choose an oscilloscope of at least 300MHz, a better bet would be 500MHz.

WisdomAugust

LAN, display, and printer interfaces enable you to integrate your oscilloscope with the
rest of your working environment.
*Video port to export the oscilloscope display to a monitor or projector.
*USB device port for easy connection to a PC or direct printing to a printer.
*USB Host port-quick and easy data storage, printing and connecting a USB keyboard.
*Ethernet port for network connection, plus compatible software to capture screen
shots, waveform data and measurement results.

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Connecting an oscilloscope to a computer directly or transferring data via portable
media allows advanced analysis, and simplifies documenting and sharing results.

*Consider an oscilloscope that allows you to access a Windows desktop and provide
network printing and file sharing resources.
*Is it helpful to provide internet access, and share measurements with colleagues
real-time?
*Check if it can run third-party analysis, documentation and productivity software.
*Can it meet your needs as they change?
-Memory to channels to analyze longer record lengths
-Application-specific measurements and application modules
-A full range of probes and modules
-Accessories like battery packs and rack mounts
-Software to control the oscilloscope from your PC, take automated measurements,
waveform data logging and export waveforms live.

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Connectivity and Expansion

Standard interfaces can include GPIB, RS-232, USB, Ethernet,
and links to network communication moduels.

USB is useful for USB flash drives to store waveforms,
captures and settings. PictBridge lets the oscilloscope
act like a digital camera. VGA connects to an external
monitor.

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Easy & Responsive Operation

Many people don't use a oscilloscope every day. Intuitive controls allow even occasional users to feel comfortable
with the oscilloscope while giving full-time users easy access to the most advanced features.

*It should be responsive, reacting quickly to changing events.
*AUTOSET and/or DEFAULT buttons will make for instant setup.
*Frequently used adjustments should have dedicated knobs.
*There should be support for your own language, with templates for the dials.

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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.

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

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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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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.

WisdomAugust

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.