Data Communications Laboratory experiment Essay Research Paper

Contents

Introduction & Test ProcedurePage 3

Test Procedure (contd.)Page 4

Peak-to-Peak voltages & Frequency explainedPage 4

ConclusionPage 4

ResultsPages 5-10

Introduction

The purpose of this laboratory exercise was to introduce the student to the techniques of using an Oscilloscope, a test meter, a waveform generator and a spectrum analyser. Three waveforms were examined; the first was a SINE WAVE; the second was a SQUARE WAVE; the third was a TRIANGULAR WAVE.

The Oscilloscope was also used to make measurements in the TIME DOMAIN and the spectrum analyser in the FREQUENCY DOMAIN.

Test Procedure

Oscilloscope measurements: We connected the output of the waveform generator to the A channel of the Oscilloscope and then the Oscilloscope setting was adjusted so that it would display the waveform as a sine wave.

Simultaneously we adjusted the frequency of the generator to 1kHz and the output level of the generator to 1V r.m.s.* using the test meter and then adjusted the Oscilloscope display so that two to three periods were shown.

*r.m.s. = route mean squared, this is the equivalent to a direct current.

Vrms.=Vmax

2

Vmax =2 x Vrms =

2 x 1 = 1.44

Therefore Vpp* = 2.825

* pp = Peak-to-Peak

Analyser Measurements: 1) Time Domain: Next we attempted to use the analyser to measure the time waveform. We connected the generator output to the input of the analyser and pressed the time button. We used the frequency buttons to adjust the scale on the time axis and we used the AMP buttons to adjust the voltage scale. It was also possible from here to make further voltage and frequency scale adjustments using the menu available on the display. These results were recorded and are documented in this report.

2) Frequency Domain: By pressing the SPECT button we were then able to observe the signal spectrum. We adjusted the frequency and zoom so that the horizontal scale occupied at least 3 kHz centred on 1kHz. These results were recorded and are documented in this report.

Peak-to-Peak Voltages

This is a measurement taken between the two maximum points of Amplitude within one cycle. (The Amplitude is the instantaneous value of signal at any time and for electromagnetic signals the amplitude is measured in volts).

e.g.

The Frequency ( )

This is the inverse of the period  = 1/T or the number of repititons of the period per second, it is expressed in cycles per second or Hertz (Hz).

The Results of this experiment are documented overleaf.

Conclusion

In conclusion, this experiment helped to familiarise me with the use of an Oscilloscope, a test meter, a waveform generator and a spectrum analyser. The experiment also helped in enhancing my understanding of terms such as, frequency (), Spectral lines, R.M.S. and Peak-to-Peak voltages.

All aspects of this experiment went smoothly and without problems, although we did struggle at one stage when we believed the analyser to have frozen, but this was as a result of forgetting to release the pause button on the machine which is used for freezing a recording.