PGT313 Digital Communication Technology. Lab 6. Spectrum Analysis of CDMA Signal

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1 PGT313 Digital Communication Technology Lab 6 Spectrum Analysis of CDMA Signal Objectives i) To measure the channel power of a CDMA modulated RF signal using an oscilloscope and the VSA software ii) To perform an in-band limit test or spectrum emission mask test on a CDMA modulated spectrum Equipment Required i) ME1100 Digital RF Communications Training Kit ii) Agilent Function a. 1 Agilent 33220B Function OR b. 1 Agilent 33522A Function iii) Agilent DSO3012A/DSO6012A/MSO7032A Oscilloscope, 100 MHz Accessories Required i) A PC running Microsoft Windows XP/Vista, pre-installed with the following: a. Agilent U1035A IQ Signal (IQG) software 1 b. Agilent VEE software (Student Edition) version 7.5 or higher c. Agilent 89601A VSA software [with option 200, 300, AYA] d. Agilent IO Libraries Suite software version 14.1 or higher for instrument ii) 2 BNC(m)-to-BNC(m) coaxial cable, 1.0 m iii) 4 SMA(m)-to-BNC(m) coaxial cable, 1.0 m iv) 3 SMA(m)-to-SMA(m) coaxial cable, 0.18 m v) 3 USB cable Channel Power Measurement Channel power is the average power in the frequency bandwidth of the signal of interest. The measurement is generally defined as power integrated over the frequency band of interest, but the actual measurement method depends on the specified communication standards [1]-[2]. 1 The U1035A IQ Signal software is an Agilent VEE (Visual Engineering Environment) program that controls the function generators via USB to generate various IQ baseband signals. It requires the Agilent VEE runtime engine to be installed on the PC. Supported modulation schemes: BPSK, QPSK, 16QAM, 32QAM, and 64QAM. PGT313 Digital Communication Technology Lab 6-1/25

Average power across bandwidth Bandwidth Figure 1 Channel Power of a Spectrum Spectrum Emission Mask (SEM) Spectrum Emission Mask (SEM) is a relative measurement of the out-of-channel emissions to

2 Average power across bandwidth Bandwidth Figure 1 Channel Power of a Spectrum Spectrum Emission Mask (SEM) Spectrum Emission Mask (SEM) is a relative measurement of the out-of-channel emissions to the in-channel power. It is commonly used to measure the excess emissions that would interfere to other channels or to other systems. SEM Figure 2 Spectrum Emission Mask PGT313 Digital Communication Technology Lab 6-2/25

3 1. Creating I and Q Baseband Signals using Agilent IQG Software 1. Make the following s (as shown in Figure 3). The system setup is similar to Lab 1. Refer to Lab 1 (Section 1) for the detailed procedure on how to configure the IQG software. Figure 3 Setup for I and Q Baseband Signal Upload and Verification 2. In the Waveform settings section of the IQG software, set the following parameters. Standard System CDMA Data Patterns PRBS 6 Modulation Format OQPSK Baseband Filter Cheb (Chebyshev) Roll-off No parameters Impairments None Symbol Rate M Maximum Sample per Symbol 4 Output Signals I and Q Output Signal Type Continuous Function Output 0.8 PGT313 Digital Communication Technology Lab 6-3/25

4 3. Download the generated IQ waveforms into the function generators. Refer to Lab 1 (Section 2) for the detailed procedure. 4. Verify the generated IQ waveform with the Agilent 6000 Series oscilloscope. Figure 4 shows a sample of the measured IQ waveform using the 6000 Series oscilloscope. I Q Figure 4 Measured IQ Waveform in the Oscilloscope 5. In the oscilloscope, use [Quick Meas] to measure the amplitude of the IQ signals. Refer to Lab 1 (Section 1, Step 14 to 15) for the detailed procedures. Amplitude of the I signal = V Amplitude of the Q signal = V PGT313 Digital Communication Technology Lab 6-4/25

2. Displaying the IQ Modulated RF Spectrum in the VSA 89600 1. Make the following s on the IQ modulator in the ME1100 training kit.

5 2. Displaying the IQ Modulated RF Spectrum in the VSA Make the following s on the IQ modulator in the ME1100 training kit. Connect the Output ports (I and Q) of both function generator to the I and Q inputs of the IQ modulator. At the rear panel of the function generator, connect the 10 MHz OUT terminal to the Input port of the 10 MHz Preamp. Next, connect the Output port of the 10 MHz Preamp to the LO port of the IQ modulator via a low pass filter. Use a jumper cable to connect the RF output of the IQ modulator to Channel 1 of the oscilloscope. Use a USB cable to connect a PC to the oscilloscope. Figure 5 Test Setup for Displaying the Modulated Baseband Signal 2. In the IQG software controller window, click Re-send to regenerate and download the IQ waveform into the function generators. 3. Configure the 6000 Series oscilloscope to interface with the VSA software (via a USB port). Refer to Lab 1 (Section 2, Step 3) for the detailed procedure on how to select a USB controller in the 6000 Series oscilloscope. PGT313 Digital Communication Technology Lab 6-5/25

4. Verify the 6000 Series oscilloscope by using the Agilent Connection Expert and ensure that the instrument is detected together with its VISA address. Refer to Lab 1 (Section 2, Step 4 to 5)

6 4. Verify the 6000 Series oscilloscope by using the Agilent Connection Expert and ensure that the instrument is detected together with its VISA address. Refer to Lab 1 (Section 2, Step 4 to 5). 5. Launch the VSA software. The VSA will be initialized and the detected hardware is as shown below. The 6000 Series oscilloscope front panel is now disabled. Note that, if the hardware is not detected, then you will need to configure the instrument so that the VSA software can recognize it. Refer to Lab 1 (Section 2, Step 7 to 9) for the detailed procedures for configuring the instrument. Figure 6 Detected Hardware Connected to VSA Software 6. Set the display layout to Single by clicking the Trace Layout icon. Next, right-click to enable the Y Auto Scale. PGT313 Digital Communication Technology Lab 6-6/25

Figure 7 Setting the Display Format in the VSA 89600 Window

Figure 8 Setting the Center Frequency and the Frequency Span

7 Figure 7 Setting the Display Format in the VSA Window 7. Select MeasSetup > Frequency. Set the center frequency to 10 MHz and the frequency span to 5 MHz, as shown below. Figure 8 Setting the Center Frequency and the Frequency Span in VSA 8. At the Average tab, set the averaging to RMS (Video) by 10 counts. PGT313 Digital Communication Technology Lab 6-7/25

5 MHz bandwidth and Mean power. Figure 10 Measuring Band Power of the Modulated Signal 10. The measured band power is approximately 4.

8 Figure 9 Setting the Average Type 9. Select Markers > Calculation and enable the Band Power calculation at the center frequency of 10 MHz with 1.5 MHz bandwidth and Mean power. Figure 10 Measuring Band Power of the Modulated Signal 10. The measured band power is approximately 4.08 dbm as shown below. Figure 11 Band Power of the CDMA Modulated Signal Across 1.5 MHz Bandwidth 11. Next, to create the spectrum emission mask (SEM), select Utilities > Limit Tests to display the Limit Tests dialog box. PGT313 Digital Communication Technology Lab 6-8/25

Figure 12 Creating a New Limit Test 12. Click New to create a new test in the Limit Test Editor dialog box. In the Name box, enter Spec_mask as the name of the limit test.

This dialog box consists of three tabs, each used to define a part of the limit line. In the Name box, enter mask as the name of the limit line to be created.

9 Figure 12 Creating a New Limit Test 12. Click New to create a new test in the Limit Test Editor dialog box. In the Name box, enter Spec_mask as the name of the limit test. Once the limit lines have been defined, they will be listed here. Figure 13 Creating a New Name for the Limit Test. 13. Click New to create a new limit line in the Limit Line Editor dialog box. This dialog box consists of three tabs, each used to define a part of the limit line. In the Name box, enter mask as the name of the limit line to be created. By default, the Test Displayed Limits check box is enabled. Define an upper limit with no margin, connecting the points, and having the trace fail in a fail color. These are the default parameters. PGT313 Digital Communication Technology Lab 6-9/25

Figure 14 Creating the Limit Test Level 14. Next, select the Units tab. Set the limit line to be in the Frequency domain with a Y Format of Log (db) and Y Unit of Auto.

Select the Points tab and click New to display the Limit Point Editor dialog box. Enter 1 and select MHz. (If a "m" is entered after the number, MHz will be implied.) Enter 55 db (db is implied).

10 Figure 14 Creating the Limit Test Level 14. Next, select the Units tab. Set the limit line to be in the Frequency domain with a Y Format of Log (db) and Y Unit of Auto. The X Reference is Absolute and Y Reference is Relative to Trace Reference. Also, set the Y Trace Ref to AvgPkVal. Figure 15 Setting the Units of the Limit Test 15. Select the Points tab and click New to display the Limit Point Editor dialog box. Enter 1 and select MHz. (If a "m" is entered after the number, MHz will be implied.) Enter 55 db (db is implied). Enable the Connect from previous point check box. Click OK. 16. This point will be listed in the Points tab of the Limit Line Editor. If you are editing an existing Limit Test, click Apply and the changes to the point will automatically be applied and saved. PGT313 Digital Communication Technology Lab 6-10/25

Select Markers > Limits to display the Limits tab. In the Markers dialog box, check to enable the Limit Test checkbox and select Trace A.

11 Figure 16 Defining the X and Y Units of the Limit Test 17. Click New and create the following limit points as shown in Figure 17. Here, the limit lines from 1 MHz to 15 MHz are created. Click OK to return to the spectrum display. Figure 17 Created Limit Test Levels 18. Select Markers > Limits to display the Limits tab. In the Markers dialog box, check to enable the Limit Test checkbox and select Trace A. Next, choose Spec_mask under the Name section. This will display the Spec_mask Limit Test on the active trace. The pass or fail limit will be shown on the trace. Identify the pass and fail levels based on the defined limits. PGT313 Digital Communication Technology Lab 6-11/25

The pass or fail limit will be shown on the trace, as depicted below.

12 Figure 18 Setting Upper1 Limit Test on the Active Trace 19. This will display the Spec_mask Limit Test on the active trace. The pass or fail limit will be shown on the trace, as depicted below. Here, the CDMA spectrum is well below the mask or limit defined, indicating a PASS condition. SEM Channel Power Figure 19 Spec_mask Limit Test on the Active Trace PGT313 Digital Communication Technology Lab 6-12/25

13 3. Measuring the IQ Modulated RF Spectrum after an Amplifier 1. Make the following s by connecting an amplifier after the signal generator. Before making any, turn off all RF output power of the function generators and oscilloscope, and close the VSA software. Use a jumper cable to connect the Output (Out) of the IQ Modulator to the Input (In) of the 10 MHz Amplifier. Next, connect the Output (Out) of the 10 MHz Amplifier to Channel 1 of the oscilloscope. Turn on all the RF output power and launch the VSA software. Connect a 5 V DC supply to the amplifier. Figure 20 Test Setup for Measuring the Output Channel Power after the Amplifier PGT313 Digital Communication Technology Lab 6-13/25

2. Repeat the procedure in Section 2 to determine the channel power after the amplifier with 10 counts averaging. What is the channel power after amplification?

14 2. Repeat the procedure in Section 2 to determine the channel power after the amplifier with 10 counts averaging. What is the channel power after amplification? Hence, determine the gain of the amplifier. Channel power after amplification = dbm Gain of the amplifier = db 3. Now, is the CDMA spectrum after amplification below or above the mask, or limit defined? 4. Measuring the Modulated RF Spectrum after an Amplifier and a Filter 1. Connect a 10 MHz filter after the amplifier output, as shown in Figure 21. Before making any, turn off all RF output power of the function generators and oscilloscope, and close the VSA software. Use a jumper cable to connect the Output (Out) of the Amplifier to the Input (In) of the 10 MHz Filter. Next, connect the Output (Out) of the 10 MHz Filter to Channel 1 of the oscilloscope. Figure 21 Test Setup for Measuring the Output Channel Power after the Amplifier and Filter PGT313 Digital Communication Technology Lab 6-14/25

15 2. Repeat the procedure in Section 2 to determine the channel power after the filter with 10 counts averaging. What is the channel power after amplification and then filtering? Hence, determine the loss of the filter. Channel power after amplification and then filtering = dbm Loss of the filter = db 3. Now, is the CDMA spectrum after amplification below or above the mask, or limit defined? 4. Repeat the measurements by connecting the Output of the RF signal generator to the 10 MHz Filter first, and then follow by the 10 MHz Amplifier. Are the results the same? 5. What is the preferred, IQ Modulator-Amplifier or IQ Modulator-Amplifier-Filter? PGT313 Digital Communication Technology Lab 6-15/25

16 References [1] Bernard Sklar, Digital Communications: Fundamentals and Applications, Prentice Hall, 2 nd Edition, [2] Agilent Application Note 1313, Testing and Troubleshooting Digital RF Communications Transmitter Designs, Literature Number E. [3] Agilent Application Note 1394, Connected Simulations and Test Solutions Using the Advanced Design System, Literature Number E. [4] Agilent Application Note, Agilent 6000 Series Oscilloscopes Performance Guide Using Vector Signal Analyzer Software, Literature Number E. [5] Agilent Technologies Parameter Interactions, Agilent Series Online Help Documentation, Tutorial Section, Theory of Operation. Available free of charge using the VSA demo CD, Literature Number E. [6] Series Vector Signal Analyzers Installation and Service Guide, Publication Number [7] Agilent Application Note, Understanding Time and Frequency Domain Interactions in the Agilent Technologies Series Vector Signal Analyzers, Literature Number E. PGT313 Digital Communication Technology Lab 6-16/25

Channel 1 and Channel 2 respectively. Note that Channel 1 represents the I-baseband signal while Channel 2 represents the Q-baseband signal.

17 Appendix A.1 By using two RF cables with a characteristic impedance of 50, connect the Output ports (Channel 1 and Channel 2) of the arbitrary waveform generators (or function generators) to the oscilloscope Channel 1 and Channel 2 respectively. Note that Channel 1 represents the I-baseband signal while Channel 2 represents the Q-baseband signal. At the rear panels of the function generators, connect the 10 MHz In terminal of a function generator to the 10 MHz Out terminal of the other function generator via a BNC-to-BNC cable. It is also important to connect the Common Trigger terminals of both function generators together. Use two USB cables to connect a PC, pre-installed with the Agilent IQG software, to both function generators. PC running Agilent IQG software (System controller) 10 MHz In-to-10 MHz Out and Common Trigger DSO6012A/DSO7012A Oscilloscope Ch 1 I-Signal Q-Signal Ch 2 Figure A.1 Basic Setup for IQ Signal Generation and Verification PGT313 Digital Communication Technology Lab 6-17/25

18 PGT313 Digital Communication Technology Lab 6-18/25

19 Appendix A.2 Connect the Output ports (I and Q) of both function generators to the I and Q inputs of the IQ modulator. At the rear panel of the function generator, connect the 10 MHz OUT terminal to the input port of 10 MHz Preamp. Use a jumper cable to connect the RF output of the IQ modulator to Channel 1 of the oscilloscope. Use a USB cable to connect a PC to the oscilloscope. Turn on all the RF output power. Connect a 5 V DC supply to the ME1100 training kit PC running IQG software and 89601A VSA software 10 MHz Out 10 MHz In- to-10 MHz Out and Common Trigger DSO6012A/DSO7012A Oscilloscope 10 MHz output Ch 1 I-Signal Q-Signal Low Pass Filter I 90 0 LO Q IQ Modulator RF 10 MHz Filter ME1100 Training Kit DC Power Supply Figure A.2 Setup for Measuring the Output Power after the IQ Modulator PGT313 Digital Communication Technology Lab 6-19/25

20 Appendix A.3 Connect the Output ports (I and Q) of both function generators to the I and Q inputs of the IQ modulator. At the rear panel of the function generator, connect the 10 MHz OUT terminal to the input port of 10 MHz Preamp. Use a jumper cable to connect the RF output of the IQ modulator to the Input (In) of an on-board 10 MHz Filter. Then, connect the Output (Out) of the 10 MHz Filter to Channel 1 of the oscilloscope. Use a USB cable to connect a PC to the oscilloscope. Turn on all the RF output power. Connect a 5 V DC supply to the ME1100 training kit PC running IQG software and 89601A VSA software 10 MHz Out 10 MHz In- to-10 MHz Out and Common Trigger DSO6012A/DSO7012A Oscilloscope 10 MHz output Ch 1 I-Signal Q-Signal Low Pass Filter I 90 0 LO Q IQ Modulator RF 10 MHz Filter ME1100 Training Kit DC Power Supply Figure A.3 Setup for Measuring the Output Power after the 10MHz Filter PGT313 Digital Communication Technology Lab 6-20/25

21 Appendix A.4 Use a jumper cable to connect the Output (Out) of the 10 MHz Filter to the Input (In) of the 10 MHz Amplifier. Then, connect the Output (Out) of the 10 MHz Amplifier to Channel 1 of the oscilloscope. Turn on all the RF output power. Connect a 5 V DC supply to the ME1100 training kit PC running IQG software and 89601A VSA software 10 MHz Out 10 MHz In-to-10 MHz Out and Common Trigger DSO6012A/DSO7012A Oscilloscope 10 MHz output I-signal Ch 1 10 MHz Amplifier Q-signal Low Pass Filter I 90 0 LO Q IQ Modulator RF 10 MHz Filter ME1100 Training Kit DC Power Supply Figure A.4 Setup for Measuring the Output Power after the Amplifier PGT313 Digital Communication Technology Lab 6-21/25

22 Appendix A.5 Use a jumper cable to connect the Output (Out) of the 10 MHz Amplifier to the Input (In) of the 10 MHz Filter. Then, connect the Output (Out) of the 10 MHz Filter to Channel 1 of the oscilloscope. Turn on all the RF output power. Connect a 5 V DC supply to the ME1100 training kit PC running IQG software and 89601A VSA software 10 MHz Out 10 MHz In-to-10 MHz Out and Common Trigger DSO6012A/DSO7012A Oscilloscope 10 MHz output I-signal Ch 1 10 MHz Filter Q-signal Low Pass Filter I 90 0 LO Q IQ Modulator RF 10 MHz Amplifier ME1100 Training Kit DC Power Supply Figure A.5 Setup for Measuring the Output Power after the Amplifier PGT313 Digital Communication Technology Lab 6-22/25

23 PGT313 Digital Communication Technology Lab 6-23/25

24 Appendix B.1 Make the following s with the N9310A RF Signal and the N9320B RF Spectrum Analyzer. Connect the Output ports (I and Q) of both function generators to the I and Q inputs located at rear panel of the N9310A RF Signal. Connect the RF output of the RF Signal to the RF input of the N9320B RF Spectrum Analyzer. PC running the IQG software 10 MHz In-to-10 MHz Out and Common Trigger N9320B RF Spectrum Analyzer I-signal Q-signal N9310A RF Signal Figure B.1 Test Setup for Displaying the Modulated Baseband Signal PGT313 Digital Communication Technology Lab 6-24/25

Appendix B.2 Make the following s by connecting a filter and an amplifier after the N9310A RF Signal.

the ME1100 training kit). Next, connect the Output (Out) terminal of the 868 MHz Filter to the Input (In) terminal of the 868 MHz Amplifier.

Turn on all the RF output power. Connect a 5 V DC supply to the ME1100 training kit.

25 Appendix B.2 Make the following s by connecting a filter and an amplifier after the N9310A RF Signal. Use a jumper cable to connect the RF output of the N9310A RF Signal to the Input (In) terminal of the 868 MHz Filter (located at the bottom part of the ME1100 training kit). Next, connect the Output (Out) terminal of the 868 MHz Filter to the Input (In) terminal of the 868 MHz Amplifier. Finally, connect the Output (Out) terminal of the 868 MHz Amplifier to the RF Input of the N9320B RF Spectrum Analyzer. Turn on all the RF output power. Connect a 5 V DC supply to the ME1100 training kit. PC running IQG Software 10 MHz In-to-10 MHz Out and Common Trigger N9320B RF Spectrum Analyzer I-signal 868 MHz Amplifier Q-signal N9310A RF Signal 868 MHz Filter ME1100 Board DC Power Supply Figure B.2 Setup for Measuring the ACPRs After the Filter PGT313 Digital Communication Technology Lab 6-25/25

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