Cathode Ray Oscilloscope (CRO) consists a set of blocks. Those are vertical amplifier, delay line, trigger circuit, time base generator, horizontal amplifier, Cathode Ray Tube (CRT) & power supply. The block diagram of CRO is shown in below figure.
The function of each block of CRO is mentioned below.
The electron beam, which is produced by an electron gun gets deflected in both vertical and horizontal directions by a pair of vertical deflection plates and a pair of horizontal deflection plates respectively. Finally, the deflected beam will appear as a spot on the fluorescent screen.
In this way, CRO will display the applied input signal on the screen of CRT. So, we can analyse the signals in time domain by using CRO
We can do the following measurements by using CRO.
Now, let us discuss about these measurements one by one.
1. Measurement of Amplitude
CRO displays the voltage signal as a function of time on its screen. The amplitude of that voltage signal is constant, but we can vary the number of divisions that cover the voltage signal in vertical direction by varying volt/division knob on the CRO panel. Therefore, we will get the amplitude of the signal, which is present on the screen of CRO by using following formula.
A = j × nv
A is the amplitude
j is the value of volt/division
nv is the number of divisions that cover the signal in vertical direction.
2. Measurement of Time Period
CRO displays the voltage signal as a function of time on its screen. The Time period of that periodic voltage signal is constant, but we can vary the number of divisions that cover one complete cycle of voltage signal in horizontal direction by varying time/division knob on the CRO panel.
Therefore, we will get the Time period of the signal, which is present on the screen of CRO by using following formula.
T = k × nh
T is the Time period
j is the value of time/division
nv is the number of divisions that cover one complete cycle of the periodic signal in horizontal direction.
3. Measurement of Frequency
The frequency, f of a periodic signal is the reciprocal of time period, T. Mathematically, it can be represented as
f = 1/T
So, we can find the frequency, f of a periodic signal by following these two steps.