Sunday, 18 March 2012

Measurement of frequency using CRO/advantage of general purpose oscilloscope

  • Measurement of frequency using CRO:

The frequency of a signal is measured using oscilloscope in two methods. They are,
1. Using calibrated oscilloscope
2. Using uncelebrated oscilloscope.
Measurement of Frequency using Calibrated Oscilloscope
It is the indirect method of measurement of frequency. In this method, the frequency of unknown
signal is measured by measuring its time period.
Initially, the unknown frequency signal is applied to the vertical inputs of the CRO. Now the
horizontal sweep is turned ON and the display appealing on the screen is adjusted by varying
different control knobs provided on the front panel of CRO, till the signal is suitably displayed
on the screen. After obtaining the display of good deflection, count the number of horizontal
division for a complete cycle. From the counted horizontal divisions, the time period is computed
m=Number of division in one complete cycle
n=Setting of time base =Time/Division
From the measured time period of the signal, the unknown frequency is calculated as,

f =1/T

  • Advantage of general purpose oscilloscope :

1. General purpose CRO's are used for maintenance of electronic equipment and laboratory

2. Amplitude of signals like voltage, current, power etc., can be measured by it

3. amplitude measurement, it can measure frequency, phase angle, time delay of the
signal, time between two events, and relative timing of two related signals.

4. It has an advantage over electro-mechanical measuring devices that it can respond very well
to high frequency signals because it is completely an electronic device.

   It provides a graphical display of the amplitude of a signal as a function of time. Hence, it is
used to measure various electrical parameters.

6. It can also be used to measure capacitance, inductance.

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