Hardware Reference
In-Depth Information
vertical sensitivity of the instrument. To have this adjustment performed for
you automatically is an absolute boon!
High-resolution DSO
High-resolution DSOs are used for precision applications where it is necessary
to faithfully reproduce a waveform, and also to be able to perform an accurate
analysis of noise floor and harmonic content. Typical applications include small
signal work and high-quality audio.
Unlike the low cost which typically has 8-bit resolution and poor DC accuracy,
these units are usually accurate to better than 1% and have either 12- or 16-bit
resolution. This makes them ideal for audio, noise, and vibration measurements.
The increased resolution also allows the instrument to be used as a spectrum
analyser with very wide dynamic range (up to 100 dB). This feature is ideal for
performing noise and distortion measurements on low-level analogue circuits
and high-fidelity equipment generally (such as CD and MP3 players).
A typical specification for a high-speed DSO is:
Sampling rate:
33 MB samples per second
Resolution:
12 bits
Number of channels:
2
Choosing a computer-based DSO
Unfortunately, for newcomers to computer-based instruments, choosing a DSO
can be an somewhat daunting task. It is extreme to avoid making a costly mistake
when choosing an instrument for the first time, and a thought and research at
the outset can certainly help!
The first step (and most obvious) step is that of deciding what you want to use
the instrument for. This will usually be fairly easy if you are intending to simply
replace a conventional stand-alone instrument. It may not be quite so simple if
you are starting out from scratch! In either case, it is worth asking the following
questions:
•
What measurements will you be making on a
regular
basis?
•
What addition
measurements
or applications do you wish to perform?
•
What signal amplitudes and frequency ranges are you working with?
•
Do you need to measure pulse waveforms accurately or do you usually work
with sinusoidal signals?
•
Are your signals repetitive or are they one-off single-shot signals?
•
Do you need to measure small time intervals and precise signal amplitudes?
•
Do you need to carry out accurate measurements of noise and harmonic
distortion, or are you just interested in displaying waveforms?
•
Do you need to analyse signals in the frequency domain (i.e. spectrum
analysis) as well as the time domain (conventional waveform display)?
•
Will the DSO be used only on the bench or will it be used as a portable item
of test equipment with a laptop computer?
•
What budget is available for purchasing the instrument?
