Ateneo de Naga UniversityCollege of EngineeringElectronics and Computer Engineering DepartmentSummerS/Y 2014 - 2015

EPFE003LAB DIGITAL COMMUNICATIONS LAB INSTRUCTOR: ENGR. GILBERT DETERAName: Aonuevo, Paolo Antonio P.Date Performed: April 14, 2015Section: GEN1Lab Activity No. : 4Lab Activity Title: PCM (Pulse Code Modulation)

OBJECTIVES To be familiar with the PULSE CODE MODULATION (PCM) ENCODER module To examine the PCM in this activity Changing the value of the input voltage, we must view the data pattern of the PCM

MATERIALS AND EQUIPMENTS Digital Multimeter Connectors Digital Oscilloscope PCM Encoder Wideband True RMS Meter

PULSE CODE MODULATIONCH 2 B

4 bit LINEAR

CH - 1 A

8.33 kHz TTL sample CLK

-2.5 to 2.5 volts

PROCEDURE1. Prepare the needed materials and read the activity2. Follow the TIMS MODEL connection of PCM3. Select the TIMS companding A4 law with the on-board COMP jumper (in preparation for a later part of the experiment)4. Locate the on-board switch SW2. Put the LEFT HAND toggle DOWN and the RIGHT HAND toggle UP. This sets the frequency of a message from the module at SYNC MESSAGE. This message is synchronized to a sub-multiple of the MASTER CLK frequency.5. Use the 8.333 kHz TTL SAMPLE CLK as the PCM CLK6. Select the 4-bit encoding scheme7. Switch the front panel toggle switch to 4-BIT LINEAR8. Connect the Vin input socket to ground of the variable DC module9. Connect the frame synchronization signal FS to the oscilloscope ext. synch. Input10. Start with a DC message. This gives stable displays and enables easy identification of the quantizing levels11. On CH1-A display the frame synchronization signal FS. Adjust the sweep speed to show three frame markers. These mark the END of each frame.12. On CH2-A display the CLK signal13. Record the number of clock periods per frame14. On CH2-B displays the PCM DATA from the PCM DATA output socket15. Identify the binary word in slots 4, 3, 2, and 116. Remove the ground connection, and connect the output of the VARIABLE DC module to Vin. Sweep the DC voltage slowly backwards and forwards over its complete range, and note how the data pattern changes in discrete jumps.17. If a WIDEBAND TRUE RMS METER module is available use this to monitor DC amplitude at Vin otherwise use the oscilloscope (CH1- B). Adjust Vin to its maximum negative value. Record the DC voltage and the pattern of the 4-bit binary number.18. Slowly increase the amplitude of the DC input signal until there is a sudden change to the PCM output signal format. Record the format of the new digital word, and the input amplitude at which the change occurred.19. Continue this process over the full range of the DC supply20. Draw a diagram showing the quantizing levels and their associated binary numbers.

ACTUAL SIMULATIONPULSE CODE MODULATIONOutput waveform of the Frame Sync and the DC output(ground)

Output waveform of the frame sync and clk waveform

Output waveform of the frame sync and PCM data out@ ground DC level

Output waveform of the frame sync and PCM data out (negative voltage)

Output waveform of the frame sync and PCM data out (negative voltage)

Output waveform of the frame sync and PCM data out (negative voltage)

Output waveform of the frame sync and PCM data out (negative voltage)

Output waveform of the frame sync and PCM data out (posititve voltage)

Output waveform of the frame sync and PCM data out (posititve voltage)

Output waveform of the frame sync and PCM data out (posititve voltage)

Output waveform of the frame sync and PCM data out (posititve voltage)

ANALYSIS AND CONCLUSIONKamo nalang bhala digdi mga idol.