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GRF-1300 User Manual and Teaching Materials

Experiment 5: AM Signal Measurement

Relevant
information

Message signals are usually of a low frequency. In general,

these low frequency signals are not appropriate for
transmission. Therefore, modulation is required to transmit
messages for communication and test systems. Modulation is a
signal adjustment method used in signal transmission. It is used
to modulate a low frequency signal which carries information
with a signal of an appropriate frequency. This is used to solve
problems associated with the amplification and transmission of
weak signals. The role of modulation in RF communication
systems is essential. Not only is modulation used to modulate
the original low-frequency signal and its transmission, but it is
also used for frequency division multiplexing (FDM). If signals
with the same frequency range are transmitted on the same
channel at the same time, they can easily interfere with each
other, and hence why they are first modulated onto different
carriers so that multiple signals can be transmitted
simultaneously. These experiments start with amplitude
modulation. The spectrum analyzer is used to measure the
characteristics of AM signals, which has a great significance for
students to master FM as well as AM principles and
characteristics.

Item Equipment

Quantity Note

1

Spectrum analyzer

1

GSP-730

2

RF & Communication Trainer

1

GRF-1300

3

RF wire

2

100mm

4

RF wire

1

800mm

Experiment
equipment

5

Adapter

1

N-SMA

Experiment
goals

1.

Learn the working principals of amplitude modulation.

2.

Use the spectrum analyzer to measure the AM characteristics
of an RF signal.

Experiment
principles

Modulation is the process of moving a low-frequency signal

to a high-frequency and then transmitting the high-frequency
signal. Generally the low frequency signal carrying the original
information is called the modulating signal or baseband signal.
The high-frequency signal is known as the carrier signal. After
the carrier signal is modulated by the modulating signal, the
resultant signal is called the modulated wave. There are three
kinds of modulation methods that are used: AM, FM and phase
modulation.

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Summary of Contents for GRF-1300

Page 1: ...RF Communication Trainer GRF 1300 STUDENT BOOK USER MANUAL and TEXT BOOK GW INSTEK PART NO 82RF 13000MA1 ISO 9001 CERTIFIED MANUFACTURER ...

Page 2: ... without prior written consent of Good Will Corporation The information in this manual was correct at the time of printing However Good Will continues to improve its products and therefore reserves the right to change the specifications equipment and maintenance procedures at any time without notice Good Will Instrument Co Ltd No 7 1 Jhongsing Rd Tucheng Dist New Taipei City 236 Taiwan ...

Page 3: ...uring a Baseband Waveform 35 Experiment 3 Different Baseband Waveforms and their Harmonic Measurement 39 Experiment 4 Measurement of the RF Carrier 46 Experiment 5 AM Signal Measurement 58 Experiment 6 FM signal measurement 68 Experiment 7 Using a Spectrum Analyzer in Communication Systems 79 Experiment 8 Measurement of communication products 86 Experiment 9 Production Line Applications 89 TEST fo...

Page 4: ...ould result in damage to the GRF 1300 or to other objects or property DANGER High Voltage Attention Refer to the Manual Protective Conductor Terminal Earth Ground Terminal Do not dispose electronic equipment as unsorted municipal waste Please use a separate collection facility or contact the supplier from which this instrument was purchased Safety Guidelines General Guideline CAUTION Do not place ...

Page 5: ...ed in a solution of mild detergent and water Do not spray any liquid into the device Do not use chemicals containing harsh products such as benzene toluene xylene and acetone Operation environment Location Indoor no direct sunlight dust free almost non conductive pollution Note below and avoid strong magnetic fields Relative Humidity 80 Altitude 2000m Temperature 0 C to 40 C Pollution Degree EN 61...

Page 6: ...the Earth terminal marked with either the letter E the earth symbol or coloured Green Green Yellow The wire which is coloured Blue must be connected to the terminal which is marked with the letter N or coloured Blue or Black The wire which is coloured Brown must be connected to the terminal marked with the letter L or P or coloured Brown or Red If in doubt consult the instructions provided with th...

Page 7: ...ystems For you to easily understand the contents of this textbook we have included as many pictures and diagrams as possible to strengthen your comprehension This book is divided into a teacher version and two student versions All experiment results are included in the teacher edition In addition chapters with an asterisk indicate additional text for advanced reading not present in the student add...

Page 8: ...ule covers some of the focus points in the RF circuit theory This will be highlighted in practical experiments in later chapters FM waveforms can also be produced by using this module together with the baseband module The GSP 730 spectrum analyzer can be used to observe the various characteristics of an FM waveform The AM module and baseband module can be used together to perform amplitude modulat...

Page 9: ...iner is designed to modulate an audio signal with a carrier waveform The system takes into account the difficulties arising from RF circuit theory and knowledge It focuses on these theories and sets up experiments to understand the theoretical aspects of RF circuitry This also has the added benefit of increasing a student s interest to learn RF circuits Figure A 1 The GRF 1300 control panel Figure...

Page 10: ...anual and software Adapter 1 N SMA Adapter Student Textbook 1 RF Communication Trainer Product Specifications and Function Function Item Spec Waveforms Sine Square Triangle Frequency Range 0 1 3MHz Triangle 0 1 1MHz Step 10kHz Amplitude 1 5Vpp Base Band Harmonics Distortion 30dBc Frequency Accuracy 0 15MHz Adjustable Range 45MHz 870M 920M Step 1MHz RF FM Analysis Power Range 15dBm FM Max Frequency...

Page 11: ...time connect each module with the appropriate RF cable Figure A 3 Connection diagram between different modules 4 The UP and DOWN buttons on the Baseband module can be used to adjust the frequency of the baseband signal The baseband module is adjustable in 10kHz steps WAVE Select is used to select three different baseband waveforms When the waveform is selected the corresponding LED light will be l...

Page 12: ... and turn anticlockwise to decrease its amplitude Figure A 4 Baseband module 5 The UP and DOWN buttons on the RF Synthesizer FM module can be used to adjust the frequency of the carrier The carrier can be adjusted in 1MHz steps The Four digit display is used to display the frequency of the carrier signal FM in port and RF FM Output port are used to receive the FM signal and output the carrier sign...

Page 13: ...7 There are five test points Tp1 Tp2 Tp3 Tp4 Tp5 on the panel These five test points are set at different points in the circuit path of the connected modules Their specific locations are as shown in the Figure below They are turned on or off by their corresponding relays B1 B2 B3 B4 B5 An oscilloscope can be used to detect determine the status of the circuitry at these test points Figure A 7 Circu...

Page 14: ...k next and a window as shown below appears Figure A 8 Software installation Next click on the Continue Anyway button to continue the installation until the installation procedure is complete Figure A 9 Installation procedure is complete After the software installation is complete users can perform a system error check by sending commands to the GRF 1300 using Hyper Terminal 12 ...

Page 15: ...Introduction to the GRF 1300 Figure A 10 Operation interface for HyperTerminal 13 ...

Page 16: ...AVE Returns the waveform type on the baseband module Bn n is the relay number for the corresponding test point Returns the state open or closed of the currently selected relay WAVE 0 The waveform to sine WAVE 1 Set the waveform to triangle WAVE 2 Set the waveform to square Bn 0 n is the relay number I e B1 0 Set the relay of corresponding no to OFF Bn 1 n is the relay number I e B3 1 Set the relay...

Page 17: ...red in the time domain Oscilloscopes are well known electrical signal measurement instruments that perform measurements in the time domain 1μsec sine wave Square wave with the same period However when we observe a sine wave and a square wave with the same amplitude and period is there a way to describe the difference between them Frequency domain measurements just provide a different view point Fi...

Page 18: ...we usually to say its spectrum or frequency distribution is as follows If we compare it with a sine wave spectrum we can observe that in addition to the point at the1MHz scale other signal points also appear at higher frequencies and with decreased amplitudes Therefore it shows that a square wave also includes a combination of signals that are multiples of the frequency baseband in addition to the...

Page 19: ...Overview of the Time and Frequency Domain Time domain Frequency domain 17 ...

Page 20: ...GRF 1300 User Manual and Teaching Materials NOTES 18 ...

Page 21: ...Overview of the Time and Frequency Domain NOTES 19 ...

Page 22: ...GRF 1300 User Manual and Teaching Materials NOTES 20 ...

Page 23: ...Overview of the Time and Frequency Domain NOTES 21 ...

Page 24: ...GRF 1300 User Manual and Teaching Materials 22 NOTES ...

Page 25: ...ple a 2 4GHz signal needs to be down converted to several MHz before the Detection Display unit can process the signal Therefore a spectrum analyzer must be able to reduce the frequency band down to several MHz The first half of a spectrum analyzer is called the radio frequency module and its task is to reduce the input signal frequency A mixer and a bandpass filter are used to decrease the freque...

Page 26: ...range of the input signal level or provide more input protection to the spectrum analyzer Referring to Figure B 2 the attenuator limits the signal level coming to the mixer RF end to a certain level If the input signal is above a reference level it can cause measurement errors or cause spurious noise Figure B 2 Attenuator Attenuator Tunable LOs RF Input Detection Display Unit Mixers BPFs IF Resolu...

Page 27: ...ower RBW1 filter the components of the two tone signal are clearly distinguished from each other as a result But in the wider RBW2 filter the result is not as clear as RBW1 We can predict that if the resolution bandwidth of RBW2 is wider we could even misinterpret the result as only one signal This will also happen if these two signals are even closer together in frequency Another case is when the...

Page 28: ...BW filter the detector detects the power and coverts it to DC voltage via an ADC so that it can be displayed Figure B 6 Detector Video Bandwidth Filter However a filter is employed after the detector to filter out the noise generated by the detector This is the function of the VBW video bandwidth filter as shown in Figure B 7 Figure B 7 VBW filter 26 ...

Page 29: ... which VBW1 is less than VBW2 we can see that the magnitude of the noise floor of VBW2 is greater than that in VBW1 But notice that the average level of the noise floor remains the same The VBW filter only averages the noise level It doesn t affect the overall amplitude of the signal noise floor Figure B 8 Different VBWs VBW1 VBW2 Signal under VBW Results Noise 27 ...

Page 30: ...GRF 1300 User Manual and Teaching Materials NOTES 28 ...

Page 31: ...An Introduction to Spectrum Analyzers NOTES 29 ...

Page 32: ...s chapter we will explain the basic operating principals of a spectrum analyzer and introduce the measurement experiments Prior to this we will briefly explain how to operate the GW Instek GSP 730 spectrum analyzer For more detail about its operation please refer to the GSP 730 user manual 30 ...

Page 33: ...ctrum analyzer is used to capture some wireless signals in the environment This experiment will help students to become familiar with using spectrum analyzers as well as to arouse their curiosity in the field of RF signals Item Equipment Quantity Note 1 Spectrum analyzer 1 GSP 730 2 Adapter 1 N SMA Experiment equipment 3 Antenna 1 800 Experiment goals To become familiar with how to use the GSP 730...

Page 34: ... to set the frequency If the frequency of the signal that you want to measure is known then we can set the frequency using the center frequency and span functions If we need to measure a frequency range then we can set the start and stop frequency range Experiment contents Connect the antenna to the GSP 730 spectrum analyzer to test the radio waves in the environment Experiment steps 1 Connect the...

Page 35: ...e Peak Hold function to hold the reading of the signal on the display screen Record the frequency and amplitude of the signal Step5 5 Change the span to 5MHz Set the center frequency to each of the above three frequency points in sequence so that you can observe each one more accurately Record these three frequency points in Table 1 1 Step6 Set the center frequencies to each of the three frequency...

Page 36: ...Frequency _____Amplitude _____ Frequency _____Amplitude _____ Table 1 1 Frequency and amplitude of mobile phone s transmitter signal Question In addition to the mobile phone signal what other wireless signals can be measured in the environment 34 ...

Page 37: ...1 Spectrum analyzer 1 GSP 730 2 RF Communication Trainer 1 GRF 1300 3 RF wire 1 800mm 4 Adapter 1 N SMA Experiment goals 1 Measurement and analysis on a basic signal 2 To understand how to use the GRF 1300 system to output a baseband signal Experiment principles Set the GRF 1300 to output a 1MHz sine waveform and use the GSP 730 to measure its spectrum The working principle of a spectrum analyzer ...

Page 38: ...5MHz Start frequency 0kHz Stop frequency 5MHz Reference level 10dBm RBW Auto Step1 Frequency F1 2 5 When the first step is done steps 2 and 3 below will have already been automatically set Students may do steps 2 and 3 here is for reference only Step2 F2 0 Step3 5 Step4 F1 0 Step5 BW F1 5 Utilize the Marker function on the spectrum analyzer to determine the harmonic ratio and draw the spectrum in ...

Page 39: ...mW into the above formula X 10 log 100mW 1mW 10 2 20dBm Because the output voltage of a signal generator is often used expressed as a voltage into a 50 ohm load you must convert voltage to power A few common values are listed below Converting Voltage to dBm into 50 ohm load Vpp V Vm V Vrms V P mW dBm 10 00 5 00 3 54 250 00 23 98 5 00 2 50 1 77 62 50 17 96 2 00 1 00 0 71 10 00 10 00 1 00 0 50 0 35 ...

Page 40: ...spectrum of a theoretical sine wave and why is it different with the actual measured one 2 What is the frequency domain feature of the analyzed signal Caution 1 The output power should not exceed the rated input of the spectrum analyzer otherwise the spectrum analyzer will be damaged 2 When using the RF cable to make a connection be sure to tighten the connector 38 ...

Page 41: ...that analyzing a signal in the frequency domain often has a lot of advantages compared to analyzing a signal in the time domain You will also find that there is a relationship that exists between the time domain and the frequency domain and will thus gain a better understanding of the theory behind the Fourier series Item Equipment Quantity Note 1 Spectrum analyzer 1 GSP 730 2 RF Communication Tra...

Page 42: ... We will become familiar with using a spectrum analyzer and how to use the GRF 1300 by analyzing the spectrum of a simple triangle and square wave signal Experiment steps 1 Turn on the GRF 1300 and the GSP 730 2 Set the GRF 1300 baseband as follows Waveform triangle Frequency 1MHz Turn the input amplitude knob clockwise to the end Step1 Step2 UP Step3 3 Connect the baseband signal from the output ...

Page 43: ...and make a record by drawing a simple sketch of the spectrum in table 3 1 Step 6 2 Step 7 4 6 Select the square wave on the GRF 1300 Baseband module Do the same spectrum measurements that were performed in the previous steps Step8 7 Observe the square wave spectrum that appears on the spectrum analyzer Use the marker function to record the harmonic ratio and draw the spectrum in table 3 3 Draw the...

Page 44: ...higher order harmonics 8 After measuring the spectrum connect the output port to the input port of the oscilloscope and measure the time domain waveform of the triangle wave and square wave and record the results in Table 3 2 and Table 3 4 Experiment results 1 In the tables below record the measurement results of the time domain waveforms and the frequency domain spectrum for both the triangle and...

Page 45: ...unication and Signals Experiments Table 3 2 Time domain waveform of the 1MHz triangle wave Table 3 3 1MHz square wave spectrum test results Table 3 4 Time domain waveform of the 1MHz square wave t A t t A t 43 ...

Page 46: ...e triangle waveform measure the harmonic ratio of the 3rd and 5th harmonic For the square waveform measure the harmonic ratio of the 2nd and 3rd harmonic Harmonic ratio of the 3rd harmonic triangle wave Harmonic ratio of the 5th harmonic triangle wave 44 ...

Page 47: ...the time domain and consider the relationship to the Fourier series theory 2 Analyze the difference between the triangle and square wave spectrum Write their Fourier series in the form of a trigonometric function What relationship do you find between each harmonic and each term in the series Caution There are different ways to set the center frequency on a spectrum analyzer Set it according to you...

Page 48: ...rn in detail the working principles of PLL circuits when we study RF circuits This experiment allows students to comprehend high frequency signals by measuring the carrier frequency spectrum It also makes students recognize the basic structure of a PLL circuit In the following experiments we will further study the locked and unlocked conditions of a phase locked loop Item Equipment Quantity Note 1...

Page 49: ...ven frequency offset value where dBc is dB in relation to the center frequency The phase noise of an oscillator is normalized to the noise generated in a bandwidth of 1Hz The phase noise is usually calculated using the formula below where fm is the frequency of a single sideband from the carrier and PssB is the measured sideband power L fm PssB P0 log B 2 5 where B 1 2RBW RBW is the resolution ban...

Page 50: ...utput port on the GRF 1300 to the input terminal on GSP 730 with the RF cable 3 Set the GSP 730 as follows Span Full Span Reference level 0dBm RBW Auto Auto Step1 F2 Step2 F1 0 Step3 F1 4 On the observed spectrum use the marker function to measure the amplitude of each frequency point The Next peak function can be used to find each consecutive peak Plot the results in table 4 1 Step4 Step5 F2 5 Dr...

Page 51: ...F Synthesizer FM as follows Carrier frequency 875MHz Step1 3 Connect the RF FM output port on the GRF 1300 to the input terminal on GSP 730 with the RF cable 4 Set the GSP 730 as follows Center frequency 875MHz Span 1MHz Reference level 0dBm RBW Auto default state is 50kHz Step1 F1 5 Step2 F1 Step3 F1 Step4 BW F1 Step5 5 Record the carrier power Set the deviation of the carrier frequency fm to a d...

Page 52: ...um analyzer to measure the value Step10 Marker F3 0 Record the value then calculate the phase noise according to the formula and record the spectrum and measurement results in Table 4 3 7 Adjust the PLL output frequency to 910MHz and again measure the power and phase noise corresponding to the frequency Step11 UP Step12 F1 1 0 Step13 Record the carrier power Set the deviation carrier frequency fm ...

Page 53: ...Signals Experiments Experiment results 1 Measurement of the RF signal spectrum Table 4 1 RF Signal Spectrum 2 RF Signal Harmonic measurements Table 4 2 RF Signal Spectrum 2nd Harmonic measurement 3rd Harmonic measurement 51 ...

Page 54: ...rier Frequency Experiment results 875MHz Carrier frequency _____ Output power _____ Phase noise _____ 900MHz Carrier frequency _____ Output power _____ Phase noise _____ Table 4 3 Phase Noise measurement results 910MHz Carrier frequency _____ Output power _____ Phase noise _____ 52 ...

Page 55: ... 1 A PLL circuit is formed by which parts Explain the function of each part 2 What are the advantages of a PLL 3 Explain the causes of phase noise How can we improve phase noise Caution Be sure to tighten the connectors when connecting the RF cable 53 ...

Page 56: ...GRF 1300 User Manual and Teaching Materials NOTES 54 ...

Page 57: ...RF Communication and Signals Experiments NOTES 55 ...

Page 58: ...GRF 1300 User Manual and Teaching Materials NOTES 56 ...

Page 59: ...RF Communication and Signals Experiments NOTES 57 ...

Page 60: ...irst modulated onto different carriers so that multiple signals can be transmitted simultaneously These experiments start with amplitude modulation The spectrum analyzer is used to measure the characteristics of AM signals which has a great significance for students to master FM as well as AM principles and characteristics Item Equipment Quantity Note 1 Spectrum analyzer 1 GSP 730 2 RF Communicati...

Page 61: ... modulation and the amplitude of an AM wave is proportional to the modulating signal therefore the modulated wave can be expressed as below uAM t UAM t cosωc t Ucm 1 macosΩt cosωc t 5 3 To simplify the analysis we set the initial phase angle of both waveforms to zero In formula 5 3 ma is known as the degree of AM modulation or the AM modulation index Namely a m a cm k U m U Ω This equation indicat...

Page 62: ... Ω c ω Ω 2 a m Ucm 2 a m Ucm 2 AM Wave Spectrum Expand formula 4 3 to get the following formula 1 1 cos cos cos 2 2 AM cm c a cm c a cm c u t U t m U t m U t ω ω Ω ω Ω As can be seen here a single modulated audio signal consists of three high frequency components In addition to the carrier two new frequency components ωc Ω and ωc Ω are included One is higher than ωc known as the upper sideband and...

Page 63: ...orm and spectrum of an AM wave 2 Measure the spectrum of the AM wave with different carrier frequencies and with modulating signals with different amplitudes 1 Turn on the power to the GRF 1300 and GSP 730 2 Set the GRF 1300 as follows Set the GRF 1300 to the default power on state Connect the output port on the Baseband module to the AM in port on the AM module with an RF cable Connect the RF FM ...

Page 64: ...4 in relation to the position of the potentiometer i e the modulating amplitude Draw the spectrum diagram in Table 5 4 Step5 Step6 Marker F3 0 1 6 Turn the potentiometer counterclockwise to the half way mark Measure the voltage with the oscilloscope By changing the output amplitude of the modulating signal can you observe any change in the spectrum Record the experiment in Table 5 4 7 Turn the pot...

Page 65: ...e in the AM wave spectrum Record the result in Table 5 5 Step9 UP Step10 Marker 6 0 10 After completing the experiment steps above press the Reset button and then use the UP button on the RF Synthesizer FM module to change the frequency of the carrier signal Is there is any change in the AM wave spectrum Compare the experiment result with that of the original carrier frequency of 880MHz and record...

Page 66: ...ing voltage Modulating voltage Experiment results Vpp Carrier power _____ Modulation index _____Lower sideband power _____ Vpp Carrier power _____ Modulation index _____Lower sideband power _____ Table 5 4 Experiment results Changing the modulating voltage Vpp Carrier power _____ 64 ...

Page 67: ...er _____ Conclusion 2 Changing the modulating signal frequency Modulating frequency Experiment results Table 5 5 Experiment results Changing the modulating signal frequency 100kHz Carrier power _____ Lower sideband power _____ 300Khz Carrier power _____ Lower sideband power _____ 65 ...

Page 68: ...aching Materials 600kHz Carrier power _____ Lower sideband power _____ Conclusion 3 Changing the carrier frequency Carrier Frequency Experiment results Table 5 6 Experiment results Changing the carrier frequency 882MHz 880MHz 66 ...

Page 69: ...e the frequency of the modulating wave but keep the amplitude the same will the AM wave be affected 2 If the input cables on the AM modules were switched Connect the baseband signal to the RF in terminal and connect the carrier signal to the AM in terminal what will happen and why 67 ...

Page 70: ...iently and have a high degree of fidelity as they rely on the phase of the modulated signal and not the amplitude to carry the baseband signal The FM circuit in this experiment uses a phase locked loop The phase locked loop circuit principles described earlier can be used to study the application of a phase locked loop circuit for this section Item Equipment Quantity Note 1 Spectrum analyzer 1 GSP...

Page 71: ... modulated signal is higher than the frequency of the carrier signal At the peak of the positive half period the angular frequency of the modulated signal is at its peak In the negative half period of the modulating signal the frequency of the modulated signal is lower than the frequency of the carrier signal and its angular frequency is at its lowest The angular frequency ω of an FM wave changes ...

Page 72: ... Ω 0 cos sin cm c f U t m t ω Ω ϕ Let the initial phase angle be 0 and expand as follows cos cos sin sin sin sin cm c f c f u t U t m t t m t ω ω Ω Ω When mf 1 cos mf sin Ωt 1 sin mf sin Ωt mf sin Ωt Then we get cos sin sin cm c f cm c u t U t mU t t ω ω Ω cos cos cos 2 2 f cm f cm cm c c c m U m U U t t ω ω ω Ω t Ω We can see when mf 1 the FM wave spectrum is composed of the carrier ωc Ω frequenc...

Page 73: ...2 Δ F F When Δ F F it is wide band modulation mf 1 B 2Δ F When Δ F F it is narrow band modulation mf 1 B 2 F The amplitude of the sideband components in an FM signal is related to the frequency modulation index This can be seen in the comparison table in the appendix Below we have a few examples of the absolute magnitudes of the sidebands for signals with a modulation index of 0 5 2 41 and 5 mf 2 ...

Page 74: ...he FM wave frequency deviation 3 Observe how the frequency of the modulating signal affects the FM wave frequency deviation 1 Turn on the GRF 1300 and GSP 730 2 Set the GRF 1300 as follows Under the default state the state from power up turn the potentiometer to the minimum position Connect the output port on the Baseband module to the FM in port on the RF Synthesizer FM module with an RF cable Co...

Page 75: ...oltage with an oscilloscope Does the spectrum of the FM wave change when the output amplitude of modulating signal changes Follow the steps below to measure the frequency deviation and record it in Table 6 2 Step7 7 Adjust the potentiometer to the maximum position Repeat the above steps and record the results in Table 6 2 Step8 8 After the completing the experiment steps above see if there is any ...

Page 76: ...nimize the amplitude of the modulating signal in order to view the FM spectrum within a span of 50MHz Then use the DOWN button on the RF Synthesizer FM module to change the frequency of the carrier signal See if there is any change in FM wave spectrum Compare this result to the original carrier frequency of 880MHz and record it in Table 6 4 Step12 Step13 12 Adjust the carrier frequency again See i...

Page 77: ...nt results 1 Changing the amplitude of the modulating signal Modulatin g voltage Experiment result Table 6 2 Experimental Results Changing the amplitude of the modulating signal Vpp Frequency deviation FM index Vpp Frequency deviation FM index Vpp 75 ...

Page 78: ...hing Materials Frequency deviation FM index Conclusion 2 Changing the frequency of an FM signal Modulating frequency Experimental result Table 6 3 Experimental results Changing the frequency of the FM signal 100Khz 300Khz 600kHz 76 ...

Page 79: ... Communication and Signals Experiments 1MHz Conclusion 3 Changing the carrier frequency Carrier frequency Experimental result 875MHz Table 6 4 Experimental results Changing the carrier frequency 880MHz 77 ...

Page 80: ...asured by the oscilloscope Question 1 For FM waves if we keep the modulation signal amplitude constant and double the modulation signal frequency how will the frequency deviation and bandwidth change in the modulated signal 2 Calculate the FM index of the modulation circuit through the measured data obtained from the spectrum analyzer 78 ...

Page 81: ... bandwidth that contains a specific percentage of the total integrated power of the channel At present third generation mobile communication systems 3G are becoming ubiquitous while some countries and companies are looking to develop fourth generation mobile communication systems 4G This experiment therefore has a high practical value for the measurement of CDMA RF power and related fields Item Eq...

Page 82: ...nt channels near the transmission channel other channels can also be selected depending on the measurement requirements When two signals with similar frequencies are input into an RF power amplifier there are not only two output signals but also the inter modulation signals input signal 1 input signal 2 A typical input and output frequency spectrum is shown in Figure 7 1 Figure 7 1 RF power amplif...

Page 83: ... on the GSP 730 have a number of set ranges therefore it fine to set the RBW to Auto mode 2 OCBW measurement OCBW measurement is for measuring the bandwidth that the channel occupies for a specified amount of power This is used to measure the occupied bandwidth as a percentage of the channel power for a specified amount of power Commonly used parameters for the measurements are channel bandwidth c...

Page 84: ... 880MHz Span 10MHz Reference level 10dBm RBW Auto Step1 F1 8 8 Step2 Span F1 1 0 Step3 Amplitude F1 1 Step4 BW F1 4 Adjust the FM frequency deviation to 1MHz 2MHz in total with the amplitude knob 2MHz 5 Measure the ACPR and OCBW after these settings are performed ACPR measurement Step1 Meas 82 ...

Page 85: ...se the frequency deviation to 2MHz 4MHz in total using the amplitude knob Measure the ACPR again and record the results to table 7 1 OCBW measurement Step1 Step2 F1 Set the bandwidth of the channel that you will measure to 2MHz Step3 Set the span of the main channel space to 10MHz Step4 The OCBW is default at 90 Record the measurement data in Table 7 2 Step5 Adjust the frequency deviation of FM wa...

Page 86: ...Teaching Materials 1MHz frequency deviation results 2MHz frequency deviation results Table 7 1 ACPR measurement results Item Test No Lower ACPR1 Upper ACPR1 Lower ACPR2 Upper ACPR2 1 2 3 4 Average 2 OCBW measurement results 84 ...

Page 87: ...surement results OCBW _________ Test No CH Power OCBW Average 1 2 3 4 5 Questions Describe the definition for ACPR Caution Taking multiple measurements and the getting average value is required for ACPR and OCBW measurements Using the Average function cannot be used as it uses a logarithmic method to calculate the average 85 ...

Page 88: ... divided into different categories such as Bluetooth Wi Fi IEEE 802 11 Infrared IrDA ZigBee IEEE 802 15 4 and so on But for the current mainstream wireless mouse there are three different categories 27Mhz 2 4G and Bluetooth This experiment actually performs measurements on actual communication products a wireless mouse in this case After performing this experiment you should have a good understand...

Page 89: ...eal for peripheral equipment such as mice and keyboards The working principles behind a wireless mouse and that of a traditional mouse are the same The only difference is that the X Y position as well each button press is transmitted wirelessly via a transmitter The wireless receiver then passes this information to the host after decoding the signal The driver then tells the operating system to co...

Page 90: ... to create a signal to measure Experiment results Transmitting frequency _____ Transmitted signal power _____ Question What are the advantages for a wireless mouse to operate in the 2 4 G bandwidth Caution Use the Peak Hold function on the spectrum analyzer to capture the signal emitted from the wireless mouse It is not easy to dynamically measure the signal 88 ...

Page 91: ... a product has passed the test and return the test results using remote commands Item Equipment Quantity Note 1 Spectrum analyzer 1 GSP 730 2 RF Communication Trainer 1 GRF 1300 3 RF wire 1 800mm 100mm Experiment equipment 4 Adapter 1 N SMA Experiment goals 1 Learn how to edit the pass fail limit lines and understand how to perform pass fail testing 2 Use remote commands to read back test data fro...

Page 92: ...freq cen Return the center frequency in kHz meas freq cen Sets the center frequency for example meas freq cen_100_mhz meas freq st Returns the start frequency in kHz meas freq st Sets the start frequency for example meas freq st_100_mhz meas freq stp Returns the stop frequency in kHz meas freq stp Sets the stop frequency for example meas freq stp_100_mhz Span Commands meas span Returns the frequen...

Page 93: ... lower limit lines to perform a pass fail test on the signal from the GRF 1300 2 Use remote commands to remotely setup the spectrum analyzer 1 Turn on the GRF 1300 and GSP 730 2 Set the GRF 1300 to the power on default state 3 Connect the RF wire from the output port on the baseband module to the FM in port on the RF Synthesizer FM module Experiment steps 4 Set up the GSP 730 as follows Center fre...

Page 94: ...to the previous menu Step7 F1 6 According to the procedures above students can set the limit lines 7 Adjust the amplitude knob on the GRF 1300 Observe the Pass Fail test results and record the results to table 9 1 8 The same functionality can be achieved by sending remote commands from a PC using HyperTerminal Experiment results Table 9 1 Results for adjusting the position of the amplitude knob 5M...

Page 95: ...RF Communication and Signals Experiments 10MHz frequency deviation test results 93 ...

Page 96: ...n students analyze the causes of these malfunctions they will have an overall understanding about the relationship and principles behind each one This helps students build their knowledge of PLLs AM and FM Experiment Aim 1 Understand how and why a phase locked loop enters the lock state or loses the lock state 2 Have an understanding of the overall communication system Experiment Contents The inst...

Page 97: ...Test for Learning Outcomes Fault 2 Fault description Hypothesis Verification 2 FM Fault Simulation Fault 1 Fault description Hypothesis Verification Fault 2 95 ...

Page 98: ...GRF 1300 User Manual and Teaching Materials Fault description Hypothesis Verification Fault 3 Fault description Hypothesis Verification Fault 4 Fault description Hypothesis 96 ...

Page 99: ...Test for Learning Outcomes Verification 3 AM Fault Simulation Fault 1 Fault description Hypothesis Verification Fault 2 Fault description Hypothesis Verification 97 ...

Page 100: ...GRF 1300 User Manual and Teaching Materials Fault 3 Fault description Hypothesis Verification Fault 4 Fault description Hypothesis Verification 98 ...

Page 101: ...Test for Learning Outcomes NOTES 99 ...

Page 102: ...GRF 1300 User Manual and Teaching Materials NOTES 100 ...

Page 103: ...Test for Learning Outcomes NOTES 101 ...

Page 104: ...GRF 1300 User Manual and Teaching Materials 102 NOTES ...

Page 105: ...0 0 001 7071 07 76 9897 16 9897 25 0 003 12574 33 81 9897 21 9897 20 0 010 22360 68 86 9897 26 9897 15 0 032 39763 54 91 9897 31 9897 10 0 100 70710 68 96 9897 36 9897 5 0 316 125743 34 101 9897 41 9897 0 1 000 223606 80 106 9897 46 9897 5 3 162 397635 36 111 9897 51 9897 10 10 000 707106 78 116 9897 56 9897 15 31 623 1257433 43 121 9897 61 9897 20 100 000 2236067 98 126 9897 66 9897 25 316 228 39...

Page 106: ...m inmW P R P V log 20 uV V dBuV further log 10 mW P dBm log 20 mV V dBmV As for dB and dBc they are relative units In terms of power a difference of 20dB is equal to a difference of 100 times Question What is the difference between 0dBm and 50dBm Is it 50dB or 50dBm Answer 50dB Explanation 0dBm 1mW 50dBm 10 5mW therefore the difference of both is 105 times which equal to 50dB or a difference of 0 ...

Page 107: ... 35 150 48 7 130 73 44 80 130 73 8 116 14 52 84 116 14 9 104 99 61 59 104 99 10 96 25 71 15 96 25 11 89 24 81 66 89 24 12 83 54 93 25 83 54 13 78 84 106 07 78 84 14 74 93 120 31 74 93 15 71 63 136 14 71 63 16 68 83 153 78 68 83 17 66 45 173 46 66 45 18 64 40 195 43 64 40 19 62 64 220 01 62 64 20 61 11 247 50 61 11 25 55 96 443 16 55 96 30 53 27 789 78 53 27 35 51 81 1405 41 51 81 40 51 01 2499 75 ...

Page 108: ...1 82 24 14 01 6 16 61 66 93 16 61 7 19 12 55 80 19 12 8 21 53 47 31 21 53 9 23 81 40 59 23 81 10 25 97 35 14 25 97 11 28 01 30 62 28 01 12 29 92 26 81 29 92 13 31 71 23 57 31 71 14 33 37 20 78 33 37 15 34 90 18 36 34 90 16 36 32 16 26 36 32 17 37 62 14 41 37 62 18 38 82 12 79 38 82 19 39 91 11 36 39 91 20 40 91 10 10 40 91 25 44 68 5 64 44 68 30 46 93 3 17 46 93 35 48 25 1 78 48 25 40 49 01 1 00 4...

Page 109: ...Appendix Modulation Index and Sideband Amplitude Comparison Table 107 ...

Page 110: ...EEC For the evaluation regarding the Electromagnetic Compatibility and Low Voltage Directive the following standards were applied EMC EN 61326 1 Electrical equipment for measurement control and laboratory use EMC requirements 2006 Conducted Radiated Emission EN 55011 2009 A1 2010 ClassB Electrostatic Discharge IEC 61000 4 2 2008 Current Harmonics EN 61000 3 2 2006 A2 2009 Radiated Immunity IEC 610...

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