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Theoretical Introduction
OSCILLOSCOPES
Digital oscilloscope
DEFINITION:
■ Digital oscilloscope
This instrument that allows you view the waveform
of periodic electrical signal (even very slow) a
function time, view single event. Because the
processing digital, signals and automatic measurements
can stored and the data can transferred onto a
computer. This mode is
reserved for periodic signals.fr
. practice, the oscilloscope must sample frequency least times higher than the presumed
frequency this signal.)
Sampling
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Block diagram digital oscilloscope
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Detailed product brochures can downloaded from www.
■Sampling modes:
For "real-time" "one-shot" sampling, all the samples are
acquired single sweep.
"Equivalent time" sampling can used achieve much
higher "sampling frequencies" because the samples are
taken from several successive sweeps.
Choosing your digital oscilloscope
■ Sampling:
Operation that involves measuring the instantaneous value signal's amplitude regular intervals.
An instrument with times more storage capacity allows
you sample times more frequently for given
recording duration.4% for 8-bit ADC (28=256)
■Signal processing:
Particularly useful mathematical operations between signals: +,-,* and even complex functions (Fast Fourier
Transform (FFT), harmonic analysis, etc. This interval
determines the "horizontal resolution".
■Sampling frequency:
The inverse the sampling interval, this expressed MegaSamples per second (MS/s).
■Vertical resolution:
"Quantization" involves converting sample's value into binary number.
■Memory depth:
This expressed kilo points (kpoints) and determines
the "recording duration" according the sweep speed;
the higher is, the longer the "recording duration" will be. 1/256 0.
The "useful bandwidth" will one tenth the maximum sampling rate and will expressed MegaHertz. varies function of
the sweep speed.metrix. The vertical resolution defined the
capacity bits the Analogue/Digital Converter (ADC).
According "Shannon's theorem", this frequency must least double the frequency the signal be
observed
