Author(s) Cookson, Shireen M. Title Laboratory experiments for communications analysis Publisher Monterey, California. Naval Postgraduate School Issue Date 1995-06 URL http://hdl.handle.
NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS LABORATORY EXPERIMENTS FOR COMMUNICATIONS ANALYSIS by Shireen M. Cookson June, 1995 Thesis Advisor: Second Reader: Randy L. Borchardt Tri T. Ha Approved for public release; distribution is unlimited.
REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information.
11
Approved for public release; distribution is unlimited. LABORATORY EXPERIMENTS FOR COMMUNICATIONS ANALYSIS Shireen M. Cookson B.S., Clarkson University, 1986 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN ELECTRICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL June 1995 Author: Approved by: /Randy L. Borchardt, Thesis Advisor Tri T. Ha, Second Reader Michael A.
IV
ABSTRACT This is a set of five laboratories designed to provide a working knowledge of the subjects covered in a course on the basics of communication theory. There are a wide range of topics covered. The concepts start with spectral anaysis of signals and continue with the sampling of those signals. Sampling at and above the Nyquist rate is demonstrated, as well as the inability to reconstruct an undersampled signal. Several signals are generated and analyzed.
VI
TABLE OF CONTENTS I. INTRODUCTION 1 II. LABORATORY DEVELOPMENT NOTES 3 A. LABORATORY DESIGN 3 B. LABORATORY 1: INTRODUCTION TO LABORATORY EQUIPMENT 3 C. LABORATORY 2: SAMPLING AND CONVERSION D. ANALOG-TO-DIGITAL 4 LABORATORY 3: AMPLITUDE AND FREQUENCY MODULATION 5 E. F. LABORATORY 4: FREQUENCY-DIVISION MULTIPLEXING AND TIME-DIVISION MULTIPLEXING 6 LABORATORY 5: PHASE LOCKED LOOP 7 m. LABORATORY EQUIPMENT 9 IV. CONCLUSION 11 APPENDIX A LABORATORY 1 13 APPENDIXB.
LIST OF REFERENCES 123 INITIAL DISTRIBUTION LIST 125 vui
I. INTRODUCTION This document contains the development notes and results for a set of five laboratories designed to provide a working knowledge of the subjects covered in an introductory communications analysis course. Each appendix contains a laboratory document that will guide the student in the completion of each experiment, a data sheet to accompany each lab, a solution guide and an equipment sheet.
the original in the frequency and time domains. Two signals are compared by listening to their tones. The procedure is repeated using a double tone created by the summer circuit of laboratory 1. FM signals are generated and analyzed in the time and frequency domains. The HP8656B signal generator is also introduced in this lab. Laboratory 4 demonstrates the concepts of frequency-division multiplexing (FDM) and time-division multiplexing (TDM).
II. LABORATORY DEVELOPMENT NOTES A. LABORATORY DESIGN The majority of the development centered around providing adequate setups and circuits that would demonstrate the basic theories and concepts of communications analysis. The laboratories were developed with the following questions in mind: 1. What are the concepts that have been covered and need to be demonstrated at this particular point in the course? 2. What research circuits and/or setups will accomplish the demonstration of these concepts? 3.
the student who is unfamiliar with circuit construction in mind. For those students who are familiar with circuit construction, completion of this lab will still be beneficial. A summer circuit is designed using a /xA741 operational amplifier [Ref. 1]. The circuit provides summation of two signals with a gain of two. This circuit provides for the demonstration of basic circuit construction and analysis. Two periodic waveforms are applied as inputs and the output signal is analyzed.
(LPF). The LPF was constructed with the following specification, and components to ensure a 60dB rolloff [Ref. 1]: C3 = .01uf, Ct = 5C3 = .005 uf, R = —^— = QC, C 3 2000 Ji(.Ol)' C2 = 2C3 = .02 uf, - 16*0 v (2 1) ' v The Fourier series and transform are computed for the sampled signal and compared to the RAPIDS displays. A-D conversion is accomplished through the use of a printed circuit board constructed for the course EC2220: Applied Electronics.
the input, the output of the envelope detector and the radio. Transmission of the signal also incorporates the use of the HP8656B signal generator. Using the summer circuit of laboratory 1, two tones are added to produce a double tone signal. The AM exercise is repeated using the double tone signal. FM signals are generated using the same equipment as the AM signals. For sine wave and square wave messages, the frequency deviation, bandwidth and modulation indexes are measured and compared with theory.
Each signal component, as well as the composite wave, are measured for frequency, period and amplitude. The increase in signal bandwidth is also measured. F. LABORATORY 5: PHASE LOCKED LOOP The phase locked loop experiment completes the lab sequence. This circuit is constructed using a NE565 PLL integrated circuit based on the National Semiconductor NE/SE565 specifications. An external resistor is determined by the student using the equations provided in the lab.
in. LABORATORY EQUIPMENT The equipment required for the completion of all labs is listed in Table 1. It is recommended that each station be set up with all the equipment listed. The total number of each system required is based on 8 lab stations. This number was chosen based on an average class of 16 to 24 students. The components required are listed for stocking purposes in Table 1. In several cases the systems required exceed the stock on hand.
8 8 Speaker 8 10 AM Radio 8 1 461A Amplifier 8 7 Antenna 8 1 NE565 PLL 8 >40 4001 NOR 8 >50 CD4029B Counter 8 0 CD4051B 8 >50 XR8038 8 0 N4764 8 >40 /xA741 Op Amp 8 >50 LF198A Sample 8 35 16 70 A-D D-A PCB 8 30 Breadboard 8 30 Several Plenty on hand HP8590B Signal 1 Generator Mulitplexor and Hold LM301 Resistors and 2 Several Capacitors Table 1.
IV. CONCLUSION Overall, these laboratories cover several topics and help to build a broad scope of knowledge for the student being introduced to the field of communications. Course syllabi and notes were obtained and compared to the content to ensure no major subjects were missed. Beginning electrical engineering students will enjoy the opportunity to see circuits in action, rather than building a circuit to analyze it's internal functions.
12
APPENDIX A.
Lab 1: Introduction to Laboratory Equipment Objectives: To introduce the student to the laboratory equipment, circuit construction and troubleshooting techniques needed throughout the course.
The end of the chip with the semicircular mark is the top. The pins are numbered from the top left. See Figure 1. Section of« breadboard Vertical rows Figure 1 b) Figure 2 is a representation of a summer circuit. This circuit adds the two input signals, denoted A and B, and multiplies them by a gain of two. The pins numbers on the op-amp correspond to the numbers marked in Figure 1. Connect the circuit of Figure 2, disregarding connections to A and B. They will be connected later.
Turn off the power supply and connect the ground and the ± 15 volt leads to the circuit. Leave the power off. A +B Figure 2 Part 2: Introduction to RAPIDS oscilloscope a) Turn on the power to the RAPIDS system. Select 'Lab Students' and "RAPIDS' and hit . You will eventually see a general options screen with choices Fl to F10. Select the oscilloscope (F10). We will change the configuration of the screen using the control options posted at each workstation.
VIEWTIME: 0.0s F9 DISPLAY TYPE: Variable Compressed F8 To display channels A, B, and C, press F7. Press A and then use the up/down arrows to position the signal on the screen. Repeat for channels B and C so the signals do not overlap. b) Connect the 50 Q output of the Wavetek 132 to channel A on the RAPIDS Digital Oscilloscope Peripheral (DOP) using a BNC cable. Connect the trigger output of the Wavetek 132 (located on the back) to the trigger input on the DOP.
Adjust the Wavetek 186 settings to: Waveform: sinusoid norm (no offset) Gen mode: cont symmetry: norm atten: -20 dB Your configuration should now look like Figure 3. WAVETEK 132 WAVETEK 186 OUT OUT P3 ^ 6A oc OP © TRIG Figure 3 d) Use a T-connector at the outputs of each Wavetek to split the signals. This will enable you to continue to view your signal while applying it to your circuit. These will be your A and B inputs to your summer. Apply the inputs to the summer circuit (order is irrelevant).
inputs on channels A and B, and the output on channel C. Press F8 to label your plot. Press PRT SC to plot. e) To pause the display during acquisition mode, press . Use the up/down arrows to position the marker on the screen to measure the period and amplitude of each signal. The values will be displayed at the bottom of the screen. Make sure you are measuring the correct amplitude by selecting the channel (press A, B or C).
Press F10 until channel A is displayed. Press to pause the display to measure the spectral frequency(s). Press to reacquire the display. Repeat for channels B and C. Q: What are the measured frequency components and their amplitudes for each signal? Press F7 to label the screen and then PRT SC to print. Provide spectral plots for each signal. Q: How do these measurements compare to the theoretical FT's computed in part 2? b) Turn the power on to the oscilloscope.
to the measurements taken with the RAPIDS system? Do not disconnect your summer circuit. It will be used for laboratory 3.
Lab 1: Introduction to Laboratory Equipment Data Sheet 2e) Q: Using the RAPIDS oscilloscope, what are the measured period and amplitude as well as the calculated frequency of each signal? Q: What is the Fourier series and transform of each signal? Lab 1 Data Sheet Page 1 22
3a) Q: What are the measured frequency components and their amplitudes for each signal? Q: How do these measurements compare to the theoretical FT's computed in part 2? Q: Using the Tektronix 2445B oscilloscope, what are the measured frequency, period and amplitude of each signal? Q: How does this compare to the measurements taken with the RAPIDS system? Lab 1 Data Sheet Page 2 23
Plot check list ü 4 kHz square wave, 1 kHz sine wave and their sum.
Lab 1: Introduction to Laboratory Equipment Solutions 2e) Q: Using the RAPIDS oscilloscope, what are the measured period and amplitude as well as the calculated frequency of each signal? Channel Amp A (sine) (mv) Period (ms) Freq( 530 1.06 0.943 B (square) 470 0.250 4.000 C(A + B) 2.06 0.245 4.
Square wave: x(t) = AA 1 1 (saitot + — sin3o>* + — sin5o? + 3 5 7t ) 2 11 *(0 = — (sin2 n 4000 t + — sin2n 12000 t + — sin2it20000 t + % 3 5 *(/) = J— YW + + 4000 ) W - 4000 ) + -6(^+ 12000 ) + - b(f - 12000 ) 7c 3 - b(f 5 20000 ) + + ) + 3 - 6(7 - 20000 )] 5 Sine + Square wave: 12 x(t) = — sin27cl000* + — 2 (äW2TC4000^ 7C X(f) = J- [6(/r+ 2 + 100 °) 12000 ) + + SüI2TC 12000 t 3 + — sin27i20000 t + 5 + — b(f 3 1 + — ) W- 1°00)] +J— [ö(/"+ 4000) TU - 6(/* - 12000 ) 3
3a) Q: What are the measured frequency components and their amplitudes for each signal? A: Channel Amp (mv) Freq(KHz) A (sine) 0.394 0.976 1st harmonic 0.402 4.052 2nd harmonic 0.171 12.10 3rd harmonic 0.104 20.16 1st harmonic 0.659 0.976 2nd harmonic 0.171 4.052 3rd harmonic 0.104 12.10 4th harmonic 0.
Q: Using the tektronix 2445B oscilloscope, what are the measured frequency, period and amplitude of each signal? A: Channel Amp A (sine) (mv) Period (us) Freq I 0.60 1.067 0.938 B (square) 0.56 0.249 4.020 C(A + B) 2.16 0.248 4.090 Q: How does this compare to the measurements taken with the RAPIDS system? A: The RAPIDS system is not as accurate as the Tektronix oscilloscope. The summed wave is much easier to read on the RAPIDS system.
4 KHz square ♦ 1 KHz sine IME/DIU: toots ACTIVE CHAHS: MC II : 500 mi/liu wimrmmmm E : 500 KMiV C: I Mill 0 : 100 «Mil' IRI55E8: Ural liraillE: 0.0 S 4.SM l.U I.5J"-" 2.00 II: PArH:C:\MP» I/o FILEHRHC: hpitiys DISPIA! IVPE: brittle Ceitpressd Itftti Function, CR, SPC, ör^ Estf ■ 12:21:69 Plotl Spectrun of 1 KHz sine wave IHPM 1)01 USE: 0.0 II W ACTIVE CHftN: II L0.J « u TRftrrsLftr FREO i 0.2 0.000 kHz niHODK IVFE: R«Un
Spectruw of 4 KHz square wave mi««« mi, tom\ SAHNE RATE: SO kHz SfECtM «USD i FftlH: C:\RAPID I/O FILEHAItE: UtMnMi Enter Function, CR, SPC, or Esc Plot 3 Spectrun of 1 KHz sine ♦ 4 KHz Square mun mmt: 8.0 u p/p AC HUE CKAH: C t u TPANUAI FRED t 0.7 0.000 (Hz KIHDDIf IKE: Rectangular 0.! IRI65ER TYPE: Horn)I * 0.2 SAHPIE RAIE: SO (Hz 0.0 SFECIRA AV60: i r iJ. tr FftlH: C:\RAP10 ■ ' ■ id- J ITT i_*. 20 .V kHz STATUS:ACQUIRING I/o FllEHAIIE: KspidSys.MS Enter Functitfn.
LAB 1 Equipment List Equipment Required/Team On/Hand Wavetek 132 24 RAPIDS station 10 Tektronix DM502A 25 Tektronix PS503 35 1 Wavetek 186 12 The number of teams is limited to 12, the number of Wavetek 186's available..
32
APPENDIXE.
Lab 2: Sampling and Analog to Digital Conversion Objectives: To explore the sampling and quantization processes. To build and demonstrate the characteristics of a low pass filter. To explore the Analog-to-Digital (AD) and Digital-to-Analog (D-A) conversion techniques. To analyze the spectra of several signals.
Parti: Sample and Hold. LPF and Spectral Analysis a) Construct the circuit of Figure 1. You will need to connect a ground bus, a + 15 volt bus and a - 15 volt bus on your bread board from the power supply. The ±15 volt busses will provide power to your chips. When the circuit is fully connected, measure the ±15 volts on the DMM before connecting them to the breadboard. Turn the power supply off. Connect your ground and power. Turn the supply back on.
D = 2 V/div TRIGGER: Normal VBEWTIME: 0.0s DISPLAY TYPE: Variable Full Scale c) Set up the Wavetek 142 to produce a 1kHz square wave that varies between 0 and +5 volts (to raise the upper voltage, adjust the attenuation and the vernier). Verify the square wave characteristics by connecting the Wavetek output to DOP channel A. Using a splitter, send the square wave to the logic input of the Sample and Hold chip (pin 8), as well as channel A. This signal is your sample pulse.
Change the sample rate to 5000 Hz. Q: Calculate the first four harmonic's amplitude and frequencies for the sample pulse and the sampled output (fs = 5000 Hz and fm= 1000 Hz). g) Turn off all power. Construct the LPF circuit of Figure 2 on the same breadboard. Connect the output (pin 6 on op amp 2) to channel D. Connect the output of the sample and hold to the input of the LPF ( pin 3 on op amp 1). Turn the power on. Set the sample pulse at a frequency of 5 kHz.
the spectra averaged equals eight. You may want to plot both dB scale and volts scale to make measurements easier. Label the baseband frequency and specra components (freq and amp) Q: How do these compare to the calculated results in part If? Vary the frequency of the input while viewing the spectrum of the output of the LPF. Q: Does this behave as expected? Q: What is the cutoff frequency of the LPF? Part 2: D-AandA-D a) The D-A and A-D circuits have been pre-wired for you.
Lab 2: Sampling and Analog to Digital Conversion Data Sheet le) Q: You will not be able to make sense of the output, why not? What is the sample period and the sample pulse duration? Q: What happens when you vary the DC signal? What kind of sampling is this? If) Q: WhatistheNyquistrateof5sin2rcl000t? Q: Attach plots and comment on results.
Q: Determine the first 4 harmonics (amplitude and frequency) for the sample pulse and the sampled output (for f=5000 and 4=1000).
lh) Q: How do the plotted spectra components compare to the calculated results in part If? Q: Does varying the frequency change the spectra output as expected? Q: What is the 3dB down point of the LPF? 2b) Q: Calculate the quantization step size for this signal (a 0 to 10 volt analog input converted to an eight bit digital output). Q: Measure the quantization step size and compare with your calculations.
Q: Draw a quantizing characteristic plot for the first 3 bits.
Lab 2: Sampling and Analog to Digital Conversion Solutions le) Q: You will not be able to make sense of the output, why not? What is the sample period and the sample pulse duration? A: The sample pulses are too short to see a response. The sample period, T = 1 Hz. The duty cycle, d=0.5. The pulse duration, T =dT=(.5)(l)=5 sees. Q: What happens when you vary the DC signal? What kind of sampling is this? A: The DC value can only be varied during the actual pulse of the sample signal.
Q: Determine the first 4 harmonics (amplitude and frequency) for the sample pulse and the sampled output (for f=5000 and 4=1000). A: Sample Pulse: fs= 5000 Hz, T = 1/f = 0.0002 sec, x = (0.00Q2)(.5) = 0 .0001, A = 2.5 V Using the equation for a square wave: .4111 V = 4 — (sino* + — sin3
S(f) - TA mANf p ° XsincinTNfJ [b\f - fß ♦ nN)] ♦ 6|/ + /0(1 - «AT)]] Amp LSB USB 1st harmonic: 1.07 4000 6000 2nd harmonic: .5185 9000 11000 3rd harmonic: .4859 14000 16000 4th harmonic: .4424 21000 23000 lh) Q: How do the plotted spectra components compare to the calculated results in part If? A: Plots are attached. The frequencies and amplitudes were close to those calculated in If.
2b) Q: Calculate the quantization step size for this signal (0 to 10 volt analog input converted to an eight bit digital output). A: The resolution for 8 bit quantizing is 28 = 256. 00000000 = Ov, 11111111 = lOv, VMlc-e=9.97 v Cstepsize VFS/(2n-l) = 9.97/(256-1) = .039 v Q: Measure the quantization step size and compare with your calculations. A: By measuring the voltage required to change one bit we can tell the quantization step size is .03 volts.
2c) Q: What is happening at the output? What happens as the sample pulse frequency is varied? A: The output is unipolar. Increasing the sample frequency creates a smoother analog output.
npct at 1 KHz Sawle at 2Hlz (Naguist Rate) lIMt/OI«: 100 W T-r^uj aCIIUE CHftKS: A e c ft : 5 Mi« f : ; Mi? C : J Mi'.' 0 : 2 Mi? 'V MG'iEfi: Horm I / \ V WHIM: 0.0 $ T STäT'Jf :MUSED PMH:f:\mnF.!)t1 I/O FILEMftHE: F.ipidS'/s [chTt] 'i Us 0 HU j .D1SHM JVfE: Uariibt« Full Sc»lt Plotl input at lKHz SaHple Rate at lKllz (klow Hamist Rate) lint; Hi": 10« »S —y_ (KIIK CHftHS: ft !C ft : 5 Mi» 8 : S Mi» I "V ft- 2 Mil' I! : 2 Mio IPJ55EF:: itoniji \ UIEUTinE: 0.
IIHE/BIli: 100« Input at 1 KHz Sawple at 5 KHz (aiow Huwist Rate) .rmsu\nnrjiru\rL «CUKE CHANS: II 8 C Ff»TH:C:\SFECIRUH \ I.J STftTUS:PAUSED I/O fllEIKIIE: fspidSyj Ch.C: OISRflJ rVFE:lijrijM{Fii!ISc}| Oils (' Hl) J 5ffi3 -* B3IIl!E3Mi»3awsaa___ :39:w Plot 3 Input lKHz SaHple 5 KHz D: LFF Output IlltE/DIU: 100 w »cni/E CHNNJ: swrwniwfwmtfü m*:\smm M5fl« WE: „ri,bl! Ml sole — mm-.twsa ^ ' * """I EI®mREMMfflK&m--. JiJÄiäTL..
Spectrum of 5Kllz Sanple Pulse STftYUS-ACOUIRXH6 FftlH: :.\SPtCn!lllt I/O FILEMfittE: (tapidSys.DTl JBniBIfflraEiil» JM9:19 L Plot 5 Spectra« of 5KHz Sawple Pulse WIM DOUME: f.O » t/p flCTIUE CHAH: -10 L -20 e u -30 Il.fill:MT FEEQ 0.000 IK! ;-!o H'HfOH UFE: • •SO %0 *MW IfI56ER IVFE: HWHJI SJUFIE mv. v< m TTT SFECTRft «MS: kH3 FftlH: C:\5fEClMIH SrfllUS:AC0UERXHS 1/0 FILEHAKE: ttMfyt.Otl ' .
Spectnii ni '.jHplfd Signal Mil «i rm *~«j.W.t ti ■■ J • ■ j *V™* ■ • ■ • , Born;l mm mv SPECFRr fitf J Tur ■■i r kH2 PATH: C --ffCf'UM ~irr SNW '■ffi'tlilM I/O FIULiiir: ■•spJdfyj.orj IfflOTGSimi MMPfll 1 1:3;:«.: Plot 7 .i ■' mt ft All: T. >?E0 SpectwiH of 1 KHz Input L -55 !,* . II! Ur -C[i ■?0 "•'■*Afadii ^^^ SO« SFE( TO O kHz p/tri- i/o r nm smii/s:iicciiiniu RspiJSyj.
Spectruw of Sailed Signal io in 1 '"■' ;f Ml FflIH: C:\SPECISUH I/O FILEKftHE: fapidSys DT5 STftlUSrflCOUIRIMG llflliHfllffiilffiiSilllll Plot 9 Lab 2 Solutions Page 10 52 Ti :4.i:!ii 1...
LAB 2 Equipment List Based on 25 student class, 2-3 persons/team. Equipment Required/Team On/Hand Breadboard 1 30 Wavetek 132 1 12 Wavetek 142 1 12 RAPIDS station 1 10 Tektronix DM502A 2 25 Tektronix PS503 1 35 The number per team depend upon the RAPIDS system availability. Right now there are only 10 PC's setup in the lab. More PC's could be added with the proper software loaded but more interface hardware would have to be purchased.
54
APPENDIX C.
Lab 3: Amplitude and Frequency Modulation Objective: To generate AM and FM signals and observe their spectra. To detect, transmit and receive AM signals.
Parti: Amplitude Modulation (AM) Generation and Detection a) Turn on the power to the RAPIDS system and configure it as follows: TIME/DIV: lOOus A = 500mV/div B = 500mV/div TRIGGER: Normal VIEWTIME: 0.0s DISPLAY TYPE: Variable Compressed b) Connect the Wavetek 132 to DOP channel A and configure it to produce a 1 V peakto-peak (pp), 1kHz square wave. Ensure there is no DC offset by adjusting the DC offset switch on the back of the Wavetek 132. This will be your message signal.
WAVETEK132 WAVETEK186 VCA N OFT OUT t 6A Ö TRIG oc OP Figure 1 d) Channel B is now a conventional AM signal. Adjust the attenuation variable knob on the 186 to produce AM signals that are 100%, <100% and > 100% modulated. The modulation index can be determined from: % m - k xlOO = max " *** xlOO A max + A mm. Print a plot of the 100% modulated wave. Q: Compute and draw the spectra of the square wave input and the AM wave. Include the time and frequency representations of each.
SAMPLE RATE: 50 kHz SPECTRA AVGD: 1 MAGNITUDE SCALING: volts e) Change the signal output of the Wavetek 132 to a sine wave. Construct the envelope detector shown in Figure 2. N4764 + Vn, HXM #_ 10 KQ Figure 2 Split the AM signal output (from the Wavetek 186) and apply it the input of the envelope detector. Read the voltage across the 20 KQ resistor and send this signal to DOP channel C. Channel C is the demodulated signal. Compare this to the input signal.
f) Viewing the AM signal (channel B) on the spectrum analyzer, adjust the variable attenuation on the carrier (Wavetek 186) until the carrier is suppressed. View the signal on the oscilloscope. Notice the phase reversals at the zero crossings of the message signal. If necessary, turn down the frequency to view this, but return it to 1 kHz when complete. This is a double sideband suppressed carrier (DSBSC) signal. Look at the detected message.
b) Split the input to the Wavetek 186 so the signal off the Wavetek 132 also goes to the HP8656B signal generator input, you will directly modulate this signal onto a 1.5 MHz carrier. Connect the RF out of the HP8656B to the HP461A amplifier input. Set the amplifier on 20dB. Connect the output of the amplifier to the antenna. Plug in the radio. Verify your setup with Figure 3. Note that we are modulating our sine wave onto the 20 kHz carrier at the Wavetek 186 and separately modulating it onto a 1.
frequencies we are transmitting. Q: What are these frequencies? Sketch the impulses. Once you hear the tone on the radio, vary the message frequency to hear the tone differences. Alternate your speaker between the input signal and the detector output. Q: Compare these tones with that emitting from the radio. c) Construct the summer circuit used in Lab 1. Using a second Wavetek 132 apply a 3 kHz signal to one input and apply the 1 kHz signal from the original Wavetek 132 to the second input.
As before, the Wavetek 132 is the message signal. Set up the Wavetek 132 to produce a 1 V pp, 1kHz square wave, with the attenuation set to -20 dB. The Wavetek 186 is the carrier signal. Set the attenuation to -20dB and change the frequency to 10 kHz. b) Demonstrate the fundamental characteristic of an FM wave, the frequency deviation (maximum departure from the carrier frequency) is directly proportional to the amplitude of the modulating wave.
Lab 3: Amplitude and Frequency Modulation Data Sheet Id) Q: Compute and draw the spectra of the square wave input and the AM wave. Include the time and frequency representations of each. Q: Using the crosshairs on the Rapids system, measure the modulation index for each case (100%, <100%, >100% modulation).
Q: Compute and draw the spectra of the modulated sine wave.
Q: What are the time and frequency representations of the DSBSC signal? Q: What is the power of the DSBSC signal? Q: If the output of the envelope detector was passed through a BPF centered at 21 kHz, what type of output would we see? Sketch the output.
2a) Q: How do the tones differ? What does this tell you about the quality of this detector? 2b). Q: What are the frequencies being transmitted? Q: Compare these tones with that emitting from the radio. 2c) Q: Compare the tones heard on the radio to the original.
Q: What is the time domain complex envelope of this wave? Q: What are fandf".
Q: What is the frequency representation for the FM sine wave? Q: Measure f, f", and 2Af.
Plot check list □ Square wave and 100% AM square wave □ Square wave spectrum □ 100% modulated square wave spectrum □ Sine wave, <100% modulated sine wave and detected sine wave □ Spectrum of <100% modulated sine wave □ Sine wave, =100% modulated sine wave and detected sine wave □ Spectrum of =100% modulated sine wave □ Sine wave, >100% modulated sine wave and detected sine wave □ Spectrum of >100% modulated sine wave □ Sine wave, AM DSBSC wave and detected sine wave □ Spectrum of AM DSB
Lab 3: Amplitude and Frequency Modulation Solutions Id) Q: Compute and draw the spectra of the square wave input and the AM wave.
X(f) = j- [S(f + 20000 ) + 2 + ka-^— [b(f + 21000 ) b(f - 20000 )] + k a — [b(f + 19000 ) + b(f - 19000 )] b(f - 21000 )]+ k-^— [b(f ♦ 17000 ) + b(f - 17000 )] + b(f - 15000 )] + 2 % + kaa-^— [b(f + 23000 ) + b(f - 23000 )]+ kafl—^— [b(f + 15000 ) 6 % 10 % + * —^— [b(f + 25000 ) a + 6(/"- 25000 )] 10 it Q: Using the crosshairs on the RAPIDS system, measure the modulation index for each case. How does this effect the output of the envelope detector? A: <100% : [(5-1.6)/(5 + 1.
Q: What effect does the modualtion index have on the spectra of each signal? A: Increasing the modulation increases the sideband amplitudes and decreases the carrier amplitude. If) Q: You will have to adjust the plot scale for the detected signal (channel C), why? A: Power is decreased during modulation.
X(f) = - [-(6(7 4 2 + 19000 ) + b(f - 19000 )) +-(6(f + 21000 ) 2 + 6(f - 21000 ))] Q: What is the power of the DSBSC AM signal? P = - A] - (0.5) (l2) = 0.5 2 Q: If the output of the envelope detector was passed through a BPF centered at 21 Khz, what type of output would we see? Sketch the output. What would the frequency representation be? What would the power be? A: The output would be Single Sideband centered at 2IK: 5K X(f) = -(&(/"+ 21000 ) 8 + 10K 15K 20K b(f - 21000 )) P = — Al = .
A: The tone of the envelope detector is higher, indicating it is removing lower frequencies. It could be improved. 2b) Q: What are these frequencies? A: 1.5 MHz + 500 Hz =1,500,500 Hz 1.5 MHz - 500 Hz =1,499,500 Hz Q: Compare these tones with that emitting from the radio. A: The tone from the radio and the original tone are the same. The tone from the envelope detector is higher pitched and lower in power. Some of the frequncies in the message signal are eliminated by the envelope detector.
4 s(t) = .5cos2ir 10000 cosß(—sin2*1000 / 4 + it sin2*3000/ + 3rc 4 sin2* 5000/) 5* 4 4 4 .5sin2* 10000 sinß(—sin2* 1000 / + sin2*3000/ + sin2rc5000/) ir 3* 5* 4 4 4 Sj = cos ß(—sin2u 1000/ + sin 2% 3000/ + sin 2* 5000/) % 3% 5% 4 S0 = sin ß(—sin 2% 1000/ + 4 sin2*3000/ + 4 sin2it5000/) s compemr-(/)J =SIT + J/ SnQ 3 b) Q: What are positive and negative frequency deviations, f and f".
Q: What is the frequency representation of the FM sine wave. A: *(/> = AT,Jnm[b{f - fc - n/J ß = 1.692 J0(ß) = .4 + 6(f + fc + n/J] Jj(ß) = .5 J2(ß) = .3 73(ß) = .1 Q: Measure f, f and 2Af. What is the frequency deviation? What is ß and the bandwidth? A: f = (.75 xlO"3 - .615 xlO"3)"1 = 7407 Hz f = (1.36 xlO'3 - 1265 xlO'3)"1 = 10.526 - lOKHz 2Af=3119 Hz Af=1560Hz ß = Af/fm=1.
The plots listed below are attached in order: Plot 1: Square wave and 100% AM square wave Plot 2: Square wave spectrum Plot 3: 100% modulated square wave spectrum Plot 4: Sine wave, <100% modulated sine wave and detected sine wave Plot 5: Spectrum of <100% modulated sine wave Plot 6: Sine wave, =100% modulated sine wave and detected sine wave Plot 7: Spectrum of =100% modulated sine wave Plot 8: Sine wave, >100% modulated sine wave and detected sine wave Plot 9: Spectrum of >100% modulated
SQUARE HADE 160"/, HODULATIOH mm: mo i» AC HUE CHANS: Al A : 500 «MiO I i S00 HV/diV C ■• 1 V/4i« D : SCO KU/diV IF.I55ER: Horiul OlEliriHE: 0.0 J fA!H:C:\5fEClRUH I/O r HEMME: ttpitiys D15PLAV IVPE: brittle C«ipief«f fiter Function, CR, SPC, or Esc Plotl SQUARE HAVE SPECIRUH JAIMJ RATE: 50 1Hz SFECIFA AM: I FAN: C:\JfECHIIH kHz STATUS:flC4UIRIH6 I/O FIlEIIAtlE: S5pidSyj.
AH LESS THAN MX MODULATION HI -lill.lt: MlH.^.i'/tF-JI l-irn:ilsil:f:;piJ!yJ n-n'"ii !V.:t;l*";;"Mt CcifreiH'i .OniJillBiEDffiffliSIBiaJI. Plot 3 AN LESS THAN 1W, KODOLAIION SIIIIHE til IE: 50 kHz imm AUSD l FAN: C:\SFEC1RUH I/O FREU: hpitiyf.
Alt IHMWIOfrKItt T»E/D1U: too us ACTIUE CHAHS: mc A : 100 KV/diU I ■■ I U/diU C : 2 U/diV III'1 '.'I) Ii>:'ii' D: SOU Hl)/diV IR166EP.: »on» I ..-j'>*^----^ UIEtllltlE: 0.0 5
AN HOHILATION GREATER THAN lift IWE/DHI: 100 VS AC HUE CHAH5: IK : 500 HU/diV : IK^^^ U/liU C : 500 HV/diU m> 0 •' 500 HV/di« TRI66ER: Norn;I MEMIIIE: 0.0 f FMH:C:\SPECtllllll TW ' TTT SfftTUS:AC0UIRIH€ 1/0 FllEHAIIE: (UpidSyj tKfUV mE:Uiri>MeCtn»r«ued JBBaB!!3affl!B3ilIBHMa3l_ Plot 7 AN MODULATION GREATER THAN 190*/ SPECTRA «1)5« 1 • PAN: C:\5PECIMK I/O FILEKAHE: RapidSys.DT2 EfitiOltfibtiohJ:CR,.SPC',;tiflKb.
1 KHz SQUARE Ml HODÜLATED ON 20XHz CARRIER Plot 9 AH JSBSC iinc/Dii: too « flCTIUE (WHS: M C I A: 500 «Hill 1 ll/dio C s SWM/liq ijiNiw^^ IK IKS ER: Hor Hat *x ffif*^. *
AHJSBSC Plot 11 FH TttlE/OW: 100 «5 ACTIVE CMS: n A = 500 Hll/diu I Win C : SOO «Miv 0 = 500 HU/«ii IÜIG5EI: Kor« »I VIEUII Hit: 0.0 $ l ! Us mil:t :^SPECIHIB I/O FIl«: Sip tfSyj STATUS :«C4tllMH6 DISPLA V HPE: lariable Full Sole Entfcfr Ftinct oh, C«. SPC.
FK SQ HAUE UIHODU mi: Km iA) KISSER IVPE: torn; I SAItPLE (ME: 50 kHz SPECTRA AU60: 1 FAIR: C:\SFECIRUn StMIISillCOIIIRIIIS I/O FIIEHAHE: RspidSys.OIS Efite^ Functibh/ CR,: SPCi ör;E a. Plot 13 MIE/Htl: MO« KltUE (HMS: Al A : 500 »II/dill E: iU/ditl C: 500 mi/dfo 0 : 500 Kll/div IRICfiER: Ktrna 1 UIEiriHE: 0.0 I PftT«:C:sSP IJ^I FILEMfl BE: RapitfSys 0ISHAV IVPE:»»i»ie Full Sole Hit» Function, CRi SPC.
FH SINUSOID Will UOLTACE: tf.O (I p/p ACTIVE CHAN: I e v 1RAKSLAT HU t 0.2 0.000 IHz limOOU WE: O.i TRIGSER IVFE: U Her« I SftHPlE (ME: SO kHz SFECTRA »1160: f s 0.0 PATH: C:\SFHHIIII I/O FltfHMIE: F3pi.jJvj.0I2 *tf kHz I*"4—TIT SIA TUS: AC4UH IHfi Ji ntefTuhct MitRr.
LAB 3 Supply List Based on 25 student class, 2-3 persons/team. Equipment Required/Team On/Hand Wavetek 132 or 142 2 24 RAPIDS station 10 Tektronix DM502A 25 Tektronix PS503 35 1 Wavetek 186 12 1 Speaker 10 1 HP8656B sig gen 7 1 AM radio 1 1 461A Amp 7 1 Antenna 1 The number of teams is limited to 7, the number of HP8656B signal generators available. Although there is only one radio and antenna, the use of these is limited so they can be shared.
88
APPENDIX D.
Lab 4: Frequency-Division Multiplexing and Time-Division Multiplexing Objective: To generate Frequency-Division Multiplexed (FDM) and Time-Division Multiplexed (TDM) signals. Measure and observe the FDM spectra. Observe the composite TDM signal in the time domain.
(1) lOOß resistor (1) 10 uf capacitor (1) .1 uf capacitor (1) .047 uf capacitor (1) .0033 uf capacitor Parti: Frequency-Division Multiplexing a) Turn on the power to the HP8590B and the HP8656B systems. Press RF OFF to ensure the RF is off. Using the oscilloscope, configure one Wavetek 186 to produce a 200 mV peak-to-peak (pp), 300 kHz sine wave. This signal will be referred to as ft. Configure the second Wavetek 186 to produce a 200 mV pp, 400 kHz sine wave. This signal will be referred to as f2.
bands as you saw them in laboratory 3 on the RAPIDS screen. 4) Press MKR and place the marker on the zero frequency spike. The spike represents a DC component within the machine itself. Note that the frequency reading on the screen will not read zero. This is due to the ± 5 MHz accuracy rating on the system. On the marker menu, located on the screen press DELTA Marker. Rotate the knob to read the frequency of the lower and upper sidebands in relationship to the center frequency spike.
Q: Measure the frequencies of the spectral components and sketch them. You will have to alternate between FREQ and MKR after choosing DELTA Marker to measure each frequency. Q: What is the bandwidth of each signal? Q: What is the bandwidth of the two signals added together? Q: What is the AB to avoid crosstalk? Q: Change f^ to 50 kHz, measure, sketch and calculate the frequency spacing again.
a probe and the oscilloscope, verify the amplitude, frequency and period of each input wave. The commutator clock frequency can be measured at pin 15 of the CD4029. Q: Measure the clock frequency and period. With the information you have predict what the TDM signal will look like. The output can be seen at pin 3 of the CD4051. Increase the oscilloscope scale and ensure that each signal is being sampled in the order you predicted. Q: Measure the period of one sample of the TDM signal.
Lab 4: Frequency-Division Multiplexing and Time-Division Multiplexing Data Sheet lb) Q: What are the frequencies for the carrier (fx) and its upper and lower sidebands. Q: What are the frequencies for the carrier (f2) and its upper and lower sidebands. lc) Q: Measure the frequecies of the spectral components and sketch them.
Q: What is the AB to avoid crosstalk? Q: Change f^ to 50 kHz, measusre, sketch and calculate the frequency spacing again. Q: At what frequency does crosstalk occur? Why? Id) Q: Measure the frequencies of the carrier and all of it's sidebands and sketch the spectrum of the FDM signal. Annotate the theoretical values as well as the actual values.
Q: Measure all the frequencies again and explain the output. 2a) Q: Using a probe and the oscilloscope, verify the amplitude, frequency and period of each input wave. Q: Measure the clock frequency and period. Q: Predict what the signal will look like.
Q: Measure the period of one sample of the TDM signal. Explain how it does/does not differ from your prediction.
Lab 4: Frequency-Division Multiplexing and Time-Division Multiplexing Solutions lb) Q: What are the frequencies for the carrier (fi) and its upper and lower sidebands. A: /N 2MK 3MK 3MK Hi Q: What are the frequencies for the carrier (f2) and its upper and lower sidebands. /"N 3MK lc) 4MK 410 K Hz Q: Measure the frequencies of the spectral components and sketch them.
Q: What is the bandwidth of each signal? A: The bandwidth of each signal is 20 kHz. Q: What is the bandwidth of the two signals added together? A: The bandwidth of the combined signal is 40 kHz. Q: What is the AB to avoid inter modulation products? A: AB = 75 kHz Q: Change f^ to 50 kHz, measure, sketch and calculate the frequency spacing again. 2»K 3MK 319K34CK 3MK 444 K Q: At what frequency does crosstalk occur? Why? A: Cross talk occurs at 340 kHz.
Id) Q: Measure the frequencies of the carrier and all of it's sidebands and sketch the spectrum of the FDM signal. Annotate the theoretical values as well as the actual values. /N JO /N A JS» J& .7 .78 u» 1.22 13 1.38 lvtz 1.5 US» MBi Q: Measure all the frequencies again and explain the output. JM Ali 312 JO* JDUUS US U(U( LS6 MBz Changing the messages to 100 kHz caused the upper and lower sidebands to cross and produce crosstalk.
A: Pin 4: DC voltage at 10 volts Pin 5: input sine wave, 5 Vpp, 30 Hz, T = 0.033 sec Pin 12: triangle wave, 3 V pp, 18 Hz, T = 0.055 sec Pin 15: sine wave, 2 V pp, 18 Hz, T = 0.055 sec Q: Measure the clock frequency and period. A: f= 7.5 kHz, T = 0.133 x 10"3 sec Q: Predict what the signal will look like. SKI SIC 2 SHS3 SGI SK54 SIG2 SIG3 SJG4 Q: Measure the period of one sample of the TDM signal. Explain how it does/does not differ from your prediction. A: The measured period is at 0.
Q: What is the bandwidth of this signal? A: The bandwidth expansion factor, N, equals 4. Therefore, B = (4)(18) = 36Hz.
LAB 4 Equipment List Based on 25 student class, 2-3 persons/team. Equipment Required/Team On/Hand Wavetek 132 or 142 2 24 Tektronix DM502A 1 25 Tektronix PS503 1 35 Wavetek 186 2 12 HP8656B sig gen 1 7 HP8590B Spec An 1 9 Tektronix 2445B 1 10 Components Required/Team On/Hand 4001 NOR 1 >50 CD4029B 1 0 CD4051B 1 >50 XR8038 1 0 Resistors/Capacitors - plenty available The number of teams is limited to 7.
APPENDIXE.
Lab 5: Phase Locked Loop Objective: To use the NE565 Phase Locked Loop (PLL) integrated circuit to demodulate a FM signal. Equipment: (1) Breadboard (1) Wavetek models 132 and 186 signal generators (1) Tektronix P5S03 power supplies (1) Tektronix 2445B Oscilloscope (see lab 1 for operation) (1) Tektronix DM502A Digital Multimeter (DMM) Components: (1) NE565 PLL IC (2) 680 Q resistors (1) resistor to be determined (2) 0.1 (if capacitors (2) .
Ri, fc, and fj for Vcc = ±10 volts. Component values can be found on figure 1. 1.2 /. A 2H/, fc **A */. ' 2* N z ^ 3.6 x 103 C, i -10V 0.001 pf vm +iev -AA/V-+iov Rl tUV »smpt Figure 1 b) Build the circuit shown in figure 1 using your calculated value for Rv Measure the actual values of the resistors and capacitors used. Connect a ground bus, a + 10 volt bus and a -10 volt bus to your breadboard from an HP power supply.
c) Display a 100 kHz sine wave with an amplitude of .25 mv from the Wavetek 186, on the oscilloscope channel 2. Adjust the Wavetek 186 settings to: Waveform: sinusoid norm symmetry: norm Gen mode: cont atten: 20dB Adjust the oscilloscope settings (see lab 1 for operation) to: Chl:5v/div,AC Ch2: 500mv/div,AC After you have verified that the signal looks as expected, connect it in series with the capacitor that is connected to pin 2. Maintain a reading of the signal on channel 2.
e) Change the values ofV^ to ±6 volts. Q: Recalculate the theoretical values of f0, fc, and f, using the actual values of the resistors and capacitors. Q: What effect does the power supply to the chip have on the output. Q: Repeat the procedure used in c) to determine the lock and capture ranges and center frequency for Vcc= ± 6 volts. Q: What is the amplitude of the output? f) Change the amplitude of the input to .375 mv. Q: Measure fc, and f,. Repeat for amplitudes of .5mv and 1 mv.
c) Verify that channel 3 is your message signal, channel 2 is the FM input to the PLL and channel 2 is the output signal. Move the output measurement probe to pin 7. This is the demodulated output pin. The PLL demodulates with a 90° phase shift and amplifies the signal via and internal amplifier. Q: Is the output shifted? What is the amplitude? Switch the message signal to a triangle wave. Q: Is the output shifted? What is the amplitude? Vary the frequency of the carrier.
Lab 5: Phase Lock Loop Data Sheet la) Q: Use the following equations to determine f0, fc, and f, for Vcc = ±10 volts. Component values can be found on figure 1. /=_L2_ ° V, J 4R1C1 l~ v Measured values for: Rx= lc) fmj_ x . 3.6rl03C2 , Ct= c **fl 2%\ , C2 Q: By varying the frequency, determine the range that the PLL remains locked (upper and lower frequencies).
Lock range: Capture range: Q: What is the amplitude of the output? Id) Q: Recalculate the theoretical values of f0, fc, and fj using the actual values of the resistors and capacitors. le) Q: With Vcc= ±6 volts, recalculate the theoretical values of f0, fc, and f, using the actual values of the resistors and capacitors.
Q: What effect does the Power supply to the chip have on the output. Q: What are the measured values for lock and capture ranges and center frequency for Vcc= ± 6 volts.
If) Q: What are fc, and fj for an input amplitude of .375 mv, .5mv and 1 mv? A: Amp f, fc fc lVpp 2Vpp .
2b) Q: Measure f0, fc, and f, for 4 = 1000 hz.
Lab 5: Phase Locked Loop Solutions la) Q: Use the following equations to determine f0, fc, and f, for Vcc = ±10 volts. Component values can be found on fig 1. fa 1.2 // 4*A 2nf, 8/0 T 3 = 3.6xl0 C, c 2%\ A: ¥„ = ±10 64xl03 = — 4(Ä1).001xlO~ (8X64x10^ *Rt = 4.688xl03Q = 51_2rlo3fl. 10 x - (3.6x10 3X-1*10 ■*) - .36*10 ~3 2«(51.2x10") fc 2n\ .36x10 -3 Measured values for: Rx= 4.67 kQ = 4751 Hz , Ct= 1.065 x 10'9 , C,= 100.
lc) Q: By varying the frequency, determine the range that the PLL remains locked (upper and lower frequencies). A: % rci f0 fcu flu I I I I I 33.9K 56. IK Lock range: 50.8 kHz 59.3K 62.4K 84.7K Capture range: 6.3 kHz Q: What is the amplitude of the output? A: A=10V Id) Q: Recalculate the theoretical values of f0, f„ and f[ using the actual values of the resistors and capacitors. A: V =±10 / = m 1 T — 60.319xl03 Hz 9 4(4.67rl0 )1.065xl0" 3 (8X64.
2n(48.255xl03) fc " 2*\ le) 360.72xl0"6 = 4614 .2Hz Q: With V^ ±6 volts, recalculate the theoretical values of f0, fC) and fj using the actual values of the resistors and capacitors. A: Vcc = ±10 1.2 fo3 ° 4(4.67xl0 )1.065xl0"9 fl T . (8)(^-319xl03) 60.319xl03 Hz m 80 425xlo3jyz = (S.örlO^lOO^rlO-9) = 360.72x10" 2n(80.425xl03) /,-—. 2*\ 5956 .9Hz 360.72x10" Q: What effect does the power supply to the chip have on the output.
A: The lock and capture ranges get larger as the supply voltage lowers. The center frequency remains the same. Q: What are the measured values for lock and capture ranges and center frequency for Vcc= ± 6 volts. A: f 1 fo 1 55.3K 59.9K 64.7K fB 1 16.4K inee: 86.2 kHz 1 flu 1 102.6K Capture range: 9.4 kHz Q: What is the amplitude of the output? A: A=6V If) Q: What are fc, and f, for an input amplitude of .375 mv, .5mv and 1 mv? A: 2a) Amp f, fc fc f, lVpp 16.7 54.1 65.2 99.
A; h fcl f0 feu flu I I I I I 25.5K 54.8K Lock range: 76.5 kHz 62.6K 70.4K 102K Capture range: 15.6 kHz Q: Why does this differ from the free running configuration? A: The frequency deviation causes the bandwidth to change. The changes the capture and lock ranges. 2b) Q: Measure f0, fc, and f, for ^ = 1000 hz. A: rH I tcl I t0 I icu I fju I 25.5K 55.4K 62.6K 70.4K 88.7K Lock range: 63.2 kHz 2c) Capture range: 15.
Q: What happens when the frequency exceeds the lock range? A: The circuit does not demodulate the output outside the lock range.
LAB 5 Equipment List Based on 25 student class, 2-3 persons/team. Equipment Required/Team On/Hand Wavetek 186 1 12 Wavetek 142 1 12 Tektronix DM502A 1 25 Tektronix PS503 1 35 Tektronix 2445B 1 10 1 >40 Components NE565 PLLIC Resistors/Capacitors - plenty available Plenty of components on hand for 12 teams.
LIST OF REFERENCES 1. Coughlin R. F. and Driscoll F. F., Operational Ampliphiers and Linear Integrated Circuits, Prentice Hall, Englewood Cliffs, N. J., 1991 2. Miller, G. M., Modern Electronic Communication, Regents/Prentice Hall, Englewood Cliffs, N. 1,1978 3. Haykin, S., An Introduction to Analog and Digital Communications, John Wiley and Sons Inc., New York, N. Y., 1989 4. Oliver, M. E., Laboratory Manual to Modern Electronic Communications by Gary M. Miller, Regents/Prentice Hall, Englewood Cliffs, N.
124
INITIAL DISTRIBUTION LIST 1. DefenseTechnical Information Center Cameron Station Alexandria, Virginia 22304-6145 2 2. Library, Code 52 Naval Postgraduate School Monterey, California 93943-5101 2 3. Chairman, Code EC Department of Electrical and Computer Engineering Naval Postgraduate School Monterey, California 93943-5121 1 4. Randy L. Borchardt, Code EC/Bt Department of Electrical and Computer Engineering Naval Postgraduate School Monterey, California 93943-5121 2 5. Tri T.
