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The simplest form of envelope detector is the diodedetector that consists of a diode connected betweenthe input and output of the circuit, with a resistorand capacitor in parallel from the output of thecircuit to the ground to form a low pass lter.

Envelope detector/Diode detector

The output of this circuit will be a nearly identical voltage-shifted version of the original signal.

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 Advantage Disadvantage

!implicity "istortion

#ow cost !elective fading

- Insensitive

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 A product detector is a type of demodulator used for AM and !!$ signals, where the original carrier signalis removed by multiplying the received signal with asignal at the carrier frequency %or near to it&.

It converting the envelope of the signal into thedecoded waveform by rectication as an envelope

detector would, the product detector ta'es the productof the modulated signal and a local oscillator.

Product detector 

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 Advantage Disadvantage

(an decode overmodulated AM and AMwith suppressed carrier.

)eeded to demodulate !!$signals.

*ave a higher signal tonoise ratio than the samesignal demodulated withan envelope detector.

-

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SIGNAL A!E"OR# ANDSPECTRU#   C O N T $

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RESULT

 AM "etector (ircuit withdiode

*alf 2ave

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RESULT CONT$

(ircuit without diode 3ull 2ave

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CONCLUSIONThe function of an AM detector is to demodulate the AMsignal and recover or reproduce the original sourceinformation.

The recovered signals contain the same frequencies as the

original information signal and have the same relativeamplitude characteristics.

The diode in the AM detector is act as rectication whenthe input voltage e4ceeds the barrier potential of diode,while the capacitor acts as lters.

2hen successive positive pea's of the detector input

waveform are increased the capacitors hold its chargebetween the pea's, when it reverse, the capacitorsdischarge between pea's to a value less than the ne4t pea'.

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