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analog oscilloscope vs digital oscilloscope-Difference between analog oscilloscope and digital oscilloscope

This page compares analog oscilloscope vs digital oscilloscope and mentions difference between analog oscilloscope and digital oscilloscope.

Oscilloscope is basically an electronic equipment which senses the voltage waveform. It displays voltage waveform with respect to time on the screen. A probe is required in order to connect the test point from the electronic circuit with the Oscilloscope. In general all the electronic equipments are categorized into analog and digital. Based on this, Oscilloscope are also available in analog and digital version.

Analog Oscilloscope

analog oscilloscope
Fig:1 Analog Oscilloscope

Analog oscilloscope works with continuous variable voltages. The figure-1 depicts analog oscilloscope type.

In analog oscilloscope type, voltage to be measured is applied directly to the moving electron beam. This voltage deflects the beam proportional to amplitude of the voltage. This will create the trace on the screen of the analog oscilloscope.

As mentioned analog oscilloscope deflects electron beam produced by electron gun inside CRT (Cathode Ray Tube) on fluorescent coating. As CRT is used here in the construction, it is known as Cathode Ray Oscilloscope.

It is composed of two parts viz. electron gun and deflection system. The deflection system is made of two parallel plates known as vertical deflection plates and horizontal deflection plates. In general, electron beam is made to pass through the deflection plates. Following rules apply to the movement of electron beam based on polarity of applied voltage.
➨+ve voltage to Y input results into deflection of electron beam vertically upward.
➨-ve voltage to Y input results into deflection of electron beam vertically downward.
➨+ve voltage to X input results into deflection of electron beam horizontally towards right side.
➨-ve voltage to X input results into deflection of electron beam horizontally towards left side.

Digital Oscilloscope

digital oscilloscope
Fig:2 Digital Oscilloscope

Digital oscilloscope works with binary numbers consisting of ones and zeros. The binary numbers in oscilloscope represents voltage samples. The figure-2 depicts digital oscilloscope type.

Digital Oscilloscope type reads the analog voltage waveform. It samples the waveform and converts analog voltage to the digital form with the use of ADC (Analog to Digital Converter). Later sampled binary information is used to construct the plot in the digital oscilloscope.

The digital oscilloscope types are digital storage oscilloscope, digital phosphor oscilloscope and digital sampling oscilloscope.



Following table mentions summary of difference between analog oscilloscope and digital oscilloscope.


analog oscilloscope digital oscilloscope
Direcly reads analog voltage and displays it on screen. It reads the analog voltage and converts it into digital form before being displayed on the screen.
Do not require ADC, microprocessor and acquision memory Requires ADC, microprocessor and acquisition memory
Can only analyze signal in real time as there is no storage memory available. Can analyze signal in real time as well as can analyze previously acquired large samples of data with facility of storage available.
Can not analyze high frequency sharp rise time transients Can analyze high frequency transients due to advanced DSP algorithms available and ported on microprocessor which can operate on stored samples of input voltage.

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