Digital Storage Oscilloscope
The digital storage oscilloscope input waveform is digitalized and stored in memory. Then. When needed, it is converted back into an analog signal and displayed on an oscilloscope
The input circuit and CRO probe are used in the same way as in the conventional oscilloscope. First the input signal travels through the attenuator and amplifier to the analog to ditigal converter
Its worm is the most important factor for ADC. Therefore, flash type or successful approximation type ADC is commonly used.
Next, we will see how the analog input signal is digitized. Sampling is the division of a waveform into smaller parts (also called pulse)
Holding means delaying, which means that the sampling singla will not be output immediately but will be output shortly. Let’s see what holding is done for. ADC may take some time to convert the analog signal to digital
If the next sampling pulse is given to the ADC while the conversion is in progress it will not take. This can lead to information loss In return we will not be able to reconstruct the original signal. The signal thus converted to digital is stored in memory
ADC converts data in memory into analog signal before displaying signal on CRT The analog signal from the ADC is amplified before being fed to the vertical deflection plate
The control logic circuit transmits the sweep signal to the horizontal deflection plate. It also controls and integrates the functions of all the circuits in the oscilloscope
Digital Storage Oscilloscope Advantages
- Digital Storage Oscilloscope is easier to operate and has more capability
- Storage time is infinite
- The display flexibility is available. The number of traces that can be stored and recalled depends on the size of the memory
- The cursor measurement is possible
- The characters can be displayed on screen along with the waveform information such as minimum and maximum frequency amplitude
- The X‑Y plots, B‑H curve, P‑V diagrams can be displayed
- The pre trigger viewing features allows to display the waveform before trigger pulse
- Keeping the records is possible which includes translating the raw data into finished information example: computing parameters of a captured signal like RMS value, energy stored etc.
Applications of Digital Storage Oscilloscope
- It is used to give the visual representation for a target of radar such as aeroplane, ship etc.
- It is used to check the faulty components in various circuits
- It can be used in medical field
- It can be used to measure AC as well as DC voltages and currents
- It is used to observe the radiation pattern generated by the transmitting antenna oscilloscope
- It can be used to measure inductance and capacitance
- It can be used to measure frequency time period,time interval between signals
- It can be used to observe the VI characteristics of diodes and transistors
- Audio and video recording equipments
- Testing of signals voltage in radio broadcasting equipment
- Used for testing signal voltages in circuit debugging
Dual Trace CRO
Dual beam CRO and dual trace CRO are used to compare one signal with another Two electron guns are used in the dual beam CRO. There is only one electron gun in the Dual Trace CRO. But the two vertical deflection plates alternately display faster
Thus, they are continuous to the eyes and both signals appear simultaneously The block diagram of the dual trace CRO is shown in the figure. It has two channels A and B. Each channel has its own attenuator and pre-amplifier stage.
So we can control the amplitude of the two inputs separately The pre-amplifier output of the two channels meets at the electronic switch.
The electronic switch transmits only one channel at a time to the vertical amplifier via the delay line. The dual trace oscilloscope is operated by an electronic switch in two modes
They are Alternate mode and Chopped mode
In this mode the electronic switch connects channel A and B alternately or alternately to the vertical amplifier First, the electronic switch connects channel A to the vertical amplifier for one cycle of the horizontal sweep Disconnect Channel A for the next cycle and connect channel B to the vertical amplifier
The display is blank during fly back and hold off When displaying high frequency signals the speed of the sweep signal is greater than the decay time of the CRT phosphoer so the input signals of channel A and B can be seen constantly on the screen alternate mode to display the low frequency signals can not be used
In this mode the electronic switch operates at a frequency of 100 to 500 KHz. From channel A and B are given as small segments to the vertical amplifier.
First the electronic switch connects a small segment from channel A to the vertical amplifier. Then disconnect channel A and connect a small segment from channel B to the vertical amplifier. Chopped mode is used to display low frequency signals
Also Read: Digital Energy Meter Block Diagram