Fundamentals of Telecommunication Systems

EE4330

Lab Assignment 4

Project Assignment: Build and test a Frequency Modulation modulator.

Required equipment and parts:

The Signal Generator you built

A 0.2 microfarad capacitor (provided)

Lab Power Supply

Lab Signal Generator

Lab Oscilloscope

Detailed Instructions:

1. Review drawing 5A and 5B of the ICL 8038 data sheet.

2. Solder the 0.2 µF capacitor to pin 8 of the ICL 8038 in the Signal Generator you built. Connect the positive terminal of the capacitor to pin 8. Mount the capacitor so that the negative lead can be used for the external frequency input.

3. Connect channel 1 of the oscilloscope to the sine wave output of the ICL 8038.

4. Set the output frequency of the signal generator you built to 10kHz. This signal corresponds to f_C.

5. The Lab Signal Generator will provide the modulating signal, f_m. for this experiment. Set the Lab Signal Generator outputs as follows:

a. 1000 Hz

b. Square wave

c. 1.0 V peak to peak

6. Connect the Lab Signal Generator output to the capacitor you added to your Signal Generator.

7. Adjust the Oscilloscope and Lab Sig Gen for a stable display showing two cycles of f_m. Record appropriate waveform and FFT signals.

8. Change the Lab Signal Generator’s output to a sine wave (other parameters unchanged). Record appropriate waveform and FFT signals.

9. Adjust the Lab Signal Generator to several frequencies between 100 Hz and 5 kHz. Stabilize the oscilloscope display by fine tuning fm. Record appropriate waveform and FFT signals.

10. Set f_c to 10 kHz sine wave and f_m to 5 kHz sine wave. Record screen shots of the waveform (time and frequency domains). Set f_c to 10 kHz sine wave and f_m to 5 kHz square wave. Record screen shots of the waveform (time and frequency domains). In your reports explain the difference you saw between the waveforms produced using a sine wave signal source and a square wave source.

In your report, compare (with supporting mathematical detail) the observations you expected with the observations you obtained for each of the waveforms. The report is due on July 23.