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test-and-measurement:guides:complementary-labs:lab5:start [2021/05/14 23:05] – ↷ Page moved from reference:test-and-measurement:guides:complementary-labs:lab5:start to test-and-measurement:guides:complementary-labs:lab5:start Arthur Browntest-and-measurement:guides:complementary-labs:lab5:start [2022/10/04 11:38] (current) – external edit 127.0.0.1
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 **Hardware** **Hardware**
-   * [[https://store.digilentinc.com/analog-discovery-studio-a-portable-circuits-laboratory-for-every-student/|Analog Discovery Studio]]+   * [[https://digilent.com/shop/analog-discovery-studio-a-portable-circuits-laboratory-for-every-student/|Analog Discovery Studio]]
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 **Software** **Software**
-   * [[reference:software:waveforms:waveforms-3:start|]]+   * [[software:waveforms:waveforms-3:start]]
    * [[https://www.ni.com/en-us/shop/labview/select-edition/labview-community-edition.html|LabVIEW Community]]    * [[https://www.ni.com/en-us/shop/labview/select-edition/labview-community-edition.html|LabVIEW Community]]
    * [[https://www.vipm.io/package/digilent_waveforms_vis/|Digilent WaveForms VIs]]    * [[https://www.vipm.io/package/digilent_waveforms_vis/|Digilent WaveForms VIs]]
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-Traditionally, envelope detection was accomplished using analog components to perform each step. For example, the full-wave rectifier built in [[reference:test-and-measurement:guides:complementary-labs:lab4:start]] and the low-pass filters built in [[reference:test-and-measurement:guides:complementary-labs:lab2:start]] would be used to rectify and filter the signal respectively. With the advent of better software, we can now accomplish the same thing digitally. In this section of the lab, we will use LabVIEW to acquire an AM signal and then demodulate it using envelope detection. We will also analyze the demodulated signal in both the time and frequency domain.+Traditionally, envelope detection was accomplished using analog components to perform each step. For example, the full-wave rectifier built in [[test-and-measurement:guides:complementary-labs:lab4:start]] and the low-pass filters built in [[test-and-measurement:guides:complementary-labs:lab2:start]] would be used to rectify and filter the signal respectively. With the advent of better software, we can now accomplish the same thing digitally. In this section of the lab, we will use LabVIEW to acquire an AM signal and then demodulate it using envelope detection. We will also analyze the demodulated signal in both the time and frequency domain.
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 In order to demodulate the signal, we will first acquire the signal using the Analog Discovery Studio, we will then use software to rectify the signal to receive only the positive half of the signal, finally, we will implement a digital filter to remove any of the high-frequency components and recover the original message. Along the way, we will look at the FFT of the rectified signal and the demodulated signal and compare them against what we saw in the first section of this lab. In order to demodulate the signal, we will first acquire the signal using the Analog Discovery Studio, we will then use software to rectify the signal to receive only the positive half of the signal, finally, we will implement a digital filter to remove any of the high-frequency components and recover the original message. Along the way, we will look at the FFT of the rectified signal and the demodulated signal and compare them against what we saw in the first section of this lab.
  
-This section of the lab will assume a working knowledge of the LabVIEW environment and basic programming conventions. For help with getting started in LabVIEW, including installation of the Digilent WaveForms VIs, please view the resources available here: [[reference:test-and-measurement:guides:getting-started-with-labview]].+This section of the lab will assume a working knowledge of the LabVIEW environment and basic programming conventions. For help with getting started in LabVIEW, including installation of the Digilent WaveForms VIs, please view the resources available here: [[test-and-measurement:guides:getting-started-with-labview]].
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-For testing the VI, use the same hardware setup as for the [[reference:test-and-measurement:guides:complementary-labs:lab5:start#analysis_with_waveforms|Analysis with WaveForms]] section.+For testing the VI, use the same hardware setup as for the [[test-and-measurement:guides:complementary-labs:lab5:start#analysis_with_waveforms|Analysis with WaveForms]] section.
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 {{ reference:test-and-measurement:guides:complementary-labs:lab5:wiring_diagram_-_scope_bb.png?600 |}} {{ reference:test-and-measurement:guides:complementary-labs:lab5:wiring_diagram_-_scope_bb.png?600 |}}
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 === Amplitude Modulation === === Amplitude Modulation ===
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-In a loop, generate two sinusoidal signals (the carrier and the modulating signal), with the required parameters, then create the modulated signal using the formula presented in the [[reference:test-and-measurement:guides:complementary-labs:lab5:start#amplitude_modulation_theory|Amplitude Modulation Theory]] section. You can use the same sampling rate as for the //Scope// instrument and the number of samples should be equal with the sampling rate multiplied by the acquisition time of the //Scope//.+In a loop, generate two sinusoidal signals (the carrier and the modulating signal), with the required parameters, then create the modulated signal using the formula presented in the [[test-and-measurement:guides:complementary-labs:lab5:start#amplitude_modulation_theory|Amplitude Modulation Theory]] section. You can use the same sampling rate as for the //Scope// instrument and the number of samples should be equal with the sampling rate multiplied by the acquisition time of the //Scope//.
  
 The resulting (modulated) signal should be outputted on the selected //Wavegen// channel. The resulting (modulated) signal should be outputted on the selected //Wavegen// channel.
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   * With the VI still running, change the cut-off frequency while observing the Demodulated Signal and the Demodulated Signal FFT. How does increasing the cut-off frequency of the low-pass filter affect the demodulated signal? How does decreasing the cut-off frequency of the low-pass filter affect the demodulated signal? What is the lowest cut-off frequency we can use to receive a clean signal? The highest?   * With the VI still running, change the cut-off frequency while observing the Demodulated Signal and the Demodulated Signal FFT. How does increasing the cut-off frequency of the low-pass filter affect the demodulated signal? How does decreasing the cut-off frequency of the low-pass filter affect the demodulated signal? What is the lowest cut-off frequency we can use to receive a clean signal? The highest?
   * Increase the Modulation Coefficient to 15% in steps of 1%. Observe the graphs as you do this. How does the modulation coefficient affect the demodulated signal? What happens to the demodulated signal as the modulation coefficient increases past 1?   * Increase the Modulation Coefficient to 15% in steps of 1%. Observe the graphs as you do this. How does the modulation coefficient affect the demodulated signal? What happens to the demodulated signal as the modulation coefficient increases past 1?
-  * The maximum buffer size for the Analog Discovery Studio is 8192 samples. This means that the largest number of samples we can acquire during a single read is 8192 samples. Since the number of samples has a set maximum, how else can we increase the resolution of the FFT? Recall the formula for $df$ discussed in the [[reference:test-and-measurement:guides:complementary-labs:lab5:start#measurements_in_the_frequency_domain|Measurements in the Frequency Domain]] section of this lab. What is the practical limitation of using this other method to increase the FFT resolution?+  * The maximum buffer size for the Analog Discovery Studio is 8192 samples. This means that the largest number of samples we can acquire during a single read is 8192 samples. Since the number of samples has a set maximum, how else can we increase the resolution of the FFT? Recall the formula for $df$ discussed in the [[test-and-measurement:guides:complementary-labs:lab5:start#measurements_in_the_frequency_domain|Measurements in the Frequency Domain]] section of this lab. What is the practical limitation of using this other method to increase the FFT resolution?
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 ==== Analog AM Demodulation ==== ==== Analog AM Demodulation ====
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-In this lab, we decided to demodulate by implementing a method known as envelope detection in software. However, the steps in envelope detection (rectifying and filtering) can also be done using hardware. In our previous labs we have talked about both rectification ([[reference:test-and-measurement:guides:complementary-labs:lab4:start]]) and low-pass filtering ([[reference:test-and-measurement:guides:complementary-labs:lab2:start]]). Use the knowledge and circuits you’ve built from these labs to put together a circuit that performs the same function as our software demodulator.+In this lab, we decided to demodulate by implementing a method known as envelope detection in software. However, the steps in envelope detection (rectifying and filtering) can also be done using hardware. In our previous labs we have talked about both rectification ([[test-and-measurement:guides:complementary-labs:lab4:start]]) and low-pass filtering ([[test-and-measurement:guides:complementary-labs:lab2:start]]). Use the knowledge and circuits you’ve built from these labs to put together a circuit that performs the same function as our software demodulator.
  
 Compare the results of your hardware demodulator to the ones from our software demodulator. What are some considerations and trade-offs between using a hardware system and a software system? Compare the results of your hardware demodulator to the ones from our software demodulator. What are some considerations and trade-offs between using a hardware system and a software system?
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 ===== Next Steps ===== ===== Next Steps =====
  
-For more complementary laboratories, return to the [[reference:test-and-measurement:guides:complementary-labs:start]] page of this wiki.+For more complementary laboratories, return to the [[test-and-measurement:guides:complementary-labs:start]] page of this wiki.
  
-For technical support, please visit the [[https://forum.digilentinc.com/forum/8-scopes-instruments/|Scopes and Instruments]] section of the Digilent Forums.+For technical support, please visit the [[https://forum.digilentinc.com/forum/8-test-and-measurement/|Test and Measurement]] section of the Digilent Forums.