Types of AM Receiver
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Transcript of Types of AM Receiver
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Contents
Classification of AM Radio Receivers… Crystal & TRF Receivers… Merits & Demerits… Receiver Parameters…
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Classification of AM Radio Receiver
The classification is based on the age-wise development of radio receiver.
1. Crystal Receiver2. TRF Receiver3. Super heterodyne Receiver
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Crystal Receiver It contains four basic
components1. Antenna or Aerial 2. Tuned circuit3. Detector (diode)4. Output device
(head/earphone)
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Circuit Diagram of Crystal Receiver
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How it works!
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Merits Demerits Easy to assemble
to receive local radio station.
No DC power is required for this.
Use as a DC power source for another amplifier receiver.
Instability. Insufficient
adjacent-frequency rejection.
It has poor audio quality.
It needs a high roof tip aerial of about 20 feet height.
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TRF Receiver “tuned radio frequency receiver”
It consists of five basic components…1. Antenna or Aerial2. One or more TRF Amplifier stages3. Detector (diode)4. Usually an audio amplifier
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Circuit Diagram Of TRF Receiver
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How it Works! One or more tuned RF amplifier stages. These
amplify the signal of the desired station to a level sufficient to drive the detector, while rejecting all other signals picked up by the antenna.
A detector, which extracts the audio (modulation) signal from the radio carrier signal by rectifying it.
Optionally, but almost always included, one or more audio amplifier stages which increase the power of the audio signal.
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Merits Demerits
TRF receivers are simple to design.
TRF has high sensitivity.
ability to drive the speaker to an acceptable level (to amplify)
It allow the broadcast frequency 535 KHz to 1640 KHz. But at the higher frequency, it produces difficulty in design.
Problem of instability.
It has poor audio quality.
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Receiver Parameters
SelectivitySensitivityFidelity
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Selectivity Selectivity of radio receiver is its ability to
accept a given band of frequencies & reject unwanted signals.
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Sensitivity Ability to amplify weak signals. Broadcast
receivers / radio receivers should have reasonably high sensitivity.
A measure of the ability of the receiver to produce, at the output of the receiver, an exact replica of the original source information.
Fidelity
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THANK YOUAny Questions???
