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university:courses:electronics:electronics-lab-envelope-detector [22 Feb 2018 15:09] – add intro + circuit Antoniu Miclausuniversity:courses:electronics:electronics-lab-envelope-detector [22 Feb 2018 17:01] – add procedure Antoniu Miclaus
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   * ω<sub>c</sub> - carrier frequency   * ω<sub>c</sub> - carrier frequency
  
-An envelope detector is an electronic circuit that takes a high-frequency signal as input and provides an output which is the envelope of the original signal. +An envelope detector is an electronic circuit that takes a high-frequency signal as input and provides an output which is the envelope of the original signal. (ω<sub>c</sub> >> ω<sub>m</sub>)
  
 It consists of two main elements: It consists of two main elements:
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 <WRAP centeralign> Figure 2. Envelope Detector breadboard circuit </WRAP> <WRAP centeralign> Figure 2. Envelope Detector breadboard circuit </WRAP>
 +
 +=== Procedure: ===
 +
 +Use the first waveform generator as source to provide the AM signal, with the following parameters:
 +  * k = 0.5
 +  * ω<sub>c</sub> = 10KHz
 +  * ω<sub>m</sub> = 100Hz
 +  * 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.
 +
 +<WRAP centeralign>{{:university:courses:electronics:env_detector-wgen.png|}}</WRAP>
 +
 +<WRAP centeralign> Figure 3. Generated AM signal </WRAP>
 +
 +Configure the scope so that output signal is displayed on channel 2.
 +
 +Disconnect the capacitor from the circuit and observe the output signal. A plot example is presented in Figure 4.
 +
 +<WRAP centeralign>{{:university:courses:electronics:env_detector-wav1.png|}}</WRAP>
 +
 +<WRAP centeralign> Figure 4. Positive Half of the generated AM signal </WRAP>
 +
 +Without the capacitor connected, the circuit works like a positive half-wave rectifier that keeps the part of the signal that is above 0V.
 +
 +Now connect the capacitor back to the circuit. A plot example is presented in Figure 5.
 +
 +<WRAP centeralign>{{:university:courses:electronics:env_detector-wav2.png|}}</WRAP>
 +
 +<WRAP centeralign> Figure 6. Generated AM signal </WRAP>
 +
 +The obtained signal is the envelope of the positive half wave obtained previously. It is actually the 100 Hz message signal with some 10 KHz variations on it.
university/courses/electronics/electronics-lab-envelope-detector.txt · Last modified: 10 Mar 2021 17:35 by Cristina Suteu

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