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| university:courses:electronics:electronics-lab-envelope-detector [04 Mar 2019 12:59] – [Further Reading] add ltspice files Antoniu Miclaus | university:courses:electronics:electronics-lab-envelope-detector [10 Mar 2021 17:35] (current) – updated math equation to work with Scopy's (v1.2.0) signal generator Cristina Suteu |
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| ===== Objective ===== | ===== Objective ===== |
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| In this lab activity we will use [[http://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/adalm2000.html|ADALM2000]] and [[university:tools:m2k:scopy|Scopy]] to introduce envelope detection and amplitude modulation. The signal's envelope is equivalent to its outline, and an envelope detector connects all the peaks in this signal. Envelope detection has numerous applications in the fields of signal processing and communications, one of which is amplitude modulation (AM) detection. | In this lab activity we will use [[adi>en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/adalm2000.html|ADALM2000]] and [[university:tools:m2k:scopy|Scopy]] to introduce envelope detection and amplitude modulation. The signal's envelope is equivalent to its outline, and an envelope detector connects all the peaks in this signal. Envelope detection has numerous applications in the fields of signal processing and communications, one of which is amplitude modulation (AM) detection. |
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| Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to the waveform being transmitted. That waveform may, for instance, correspond to the sounds to be reproduced by a loudspeaker, or the light intensity of television pixels. | Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to the waveform being transmitted. That waveform may, for instance, correspond to the sounds to be reproduced by a loudspeaker, or the light intensity of television pixels. |
| Consider the circuit presented in Figure 1. | Consider the circuit presented in Figure 1. |
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| <WRAP centeralign>{{:university:courses:electronics:env_detector-sch.png?500|}}</WRAP> | <WRAP centeralign>{{ :university:courses:electronics:env_detector_ltspice.png?400 |}}</WRAP> |
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| <WRAP centeralign> Figure 1. Basic Envelope Detector Circuit </WRAP> | <WRAP centeralign> Figure 1. Basic Envelope Detector Circuit </WRAP> |
| * ω<sub>m</sub> = 100Hz | * ω<sub>m</sub> = 100Hz |
| * A = 3 | * A = 3 |
| To generate the AM signal use the math function from the Scopy signal generator. Set the main frequency to 100Hz and apply the following function: //(1+0.5*cos(t))*3*cos(100*t)//. The generated waveform is presented in Figure 3. | To generate the AM signal use the math function from the Scopy signal generator. Set the record length to 20ms, the sample rate to 75MSPS and apply the following function: //(1+0.5*cos(2*pi*100*t))*3*cos(2*pi*100*100*t)//. The generated waveform is presented in Figure 3. |
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| <WRAP centeralign>{{:university:courses:electronics:env_detector-wgen.png|}}</WRAP> | <WRAP centeralign>{{:university:courses:electronics:env_detector-wgen.png|}}</WRAP> |
| Consider the circuit presented in Figure 9. | Consider the circuit presented in Figure 9. |
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| <WRAP centeralign>{{:university:courses:electronics:ext_env_detector-sch.png?400|}}</WRAP> | <WRAP centeralign>{{ :university:courses:electronics:ext_env_det.png?400 |}}</WRAP> |
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| <WRAP centeralign> Figure 9. Positive and negative Envelope Detector Circuit </WRAP> | <WRAP centeralign> Figure 9. Positive and negative Envelope Detector Circuit </WRAP> |
| * ω<sub>m</sub> = 100Hz | * ω<sub>m</sub> = 100Hz |
| * A = 3 | * A = 3 |
| To generate the AM signal use the math function from the Scopy signal generator. Set the main frequency to 100Hz and apply the following function: //(1+0.5*cos(t))*3*cos(100*t)//. The generated waveform is presented in Figure 11. (with 5 displayed periods) | To generate the AM signal use the math function from the Scopy signal generator. Set the record length to 50ms and apply the following function: //(1+0.5*cos(2*pi*100*t))*3*cos(2*pi*100*100*t)//. The generated waveform is presented in Figure 11. (with 5 displayed periods) |
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| <WRAP centeralign>{{:university:courses:electronics:ext_env_detector-wgen.png|}}</WRAP> | <WRAP centeralign>{{:university:courses:electronics:ext_env_detector-wgen.png|}}</WRAP> |
| Consider the circuit shown in Figure 14. | Consider the circuit shown in Figure 14. |
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| <WRAP centeralign>{{:university:courses:electronics:bias_env_detector-sch.png|}}</WRAP> | <WRAP centeralign>{{ :university:courses:electronics:bias_env_detector.png?400 |}}</WRAP> |
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| <WRAP centeralign> Figure 14. Biased Envelope Detector circuit </WRAP> | <WRAP centeralign> Figure 14. Biased Envelope Detector circuit </WRAP> |
| ===== Further Reading ===== | ===== Further Reading ===== |
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| | <WRAP round download> |
| **Lab Resources:** | **Lab Resources:** |
| * Fritzing files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/fritzing/env_detector_bb | env_detector_bb]] | * Fritzing files: [[downgit>education_tools/tree/master/m2k/fritzing/env_detector_bb | env_detector_bb]] |
| * LTspice files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/ltspice/env_detector_ltspice | env_detector_ltspice]] | * LTspice files: [[downgit>education_tools/tree/master/m2k/ltspice/env_detector_ltspice | env_detector_ltspice]] |
| | </WRAP> |
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| Additional resources: | Additional resources: |
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| * [[http://www.analog.com/en/technical-articles/integrated-diode-based-rf-detectors.html|Understanding, Operating, and Interfacing to Integrated Diode-Based RF Detectors]] | * [[adi>en/technical-articles/integrated-diode-based-rf-detectors.html|Understanding, Operating, and Interfacing to Integrated Diode-Based RF Detectors]] |
| * [[http://www.analog.com/media/en/technical-documentation/application-notes/AN-423.pdf|Amplitude Modulation of the AD9850 Direct Digital Synthesizer]] | * [[adi>media/en/technical-documentation/application-notes/AN-423.pdf|Amplitude Modulation of the AD9850 Direct Digital Synthesizer]] |
| * [[http://www.analog.com/en/analog-dialogue/raqs/raq-issue-92.html|Multipliers and Modulators]] | * [[adi>en/analog-dialogue/raqs/raq-issue-92.html|Multipliers and Modulators]] |
| * [[http://www.analog.com/media/en/technical-documentation/data-sheets/ADL5511.pdf|Envelope and TruPwr RMS Detector | * [[adi>media/en/technical-documentation/data-sheets/ADL5511.pdf|Envelope and TruPwr RMS Detector |
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