Superheterodyne Modellation

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Superheterodyne Receiver: Modelling
With MATLAB
Bernardo Munguambe
bernardo.munguambe@outlook.com
Telecommunications Systems - Deptartment of Radio,
Higher School of Nautical Sciences
Maputo, Mozambique
April 20, 2023
Outline Outline Introduction Superheterodyne References
Outline
1 Introduction
History
2 Superheterodyne
Definition
Block diagram
Superherodyne stages
3 References
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Introduction Outline Introduction Superheterodyne References
Introduction
History
The superheterodyne receiver is a key innovation in radio frequency
(RF) technology that revolutionized radio communication. It was
invented by American engineer and inventor Edwin Armstrong in
1918. The superheterodyne architecture has since become the stan-
dard design for most radio receivers due to its advantages in selec-
tivity, sensitivity, and stability.
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Superheterodyne Outline Introduction Superheterodyne References
Superheterodyne
Superheterodyne refers to a method of radio signal processing widely
used in the design of radio receivers. The superheterodyne receiver
architecture was developed to enhance the selectivity and sensitiv-
ity of radio receivers. In a superheterodyne receiver, incoming radio
frequency (RF) signals are mixed with a locally generated oscillator
frequency to produce an intermediate frequency (IF) that is fixed
and lower than the original RF.
Figure: Example of
Superheterodyne receiver
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Superheterodyne Outline Introduction Superheterodyne References
Block diagram
The superheterodyne receiver is a common architecture used in
radio communication systems. Its operation principle involves a
process called heterodyning, which helps in improving selectivity,
sensitivity, and tuning in a radio receiver. Here’s a simplified ex-
planation of the superheterodyne receiver’s operation:
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Superheterodyne Outline Introduction Superheterodyne References
Superherodyne stages
(1) Antenna and RF Amplification:
The incoming radio frequency (RF) signal is captured by the antenna.
An RF amplifier amplifies the weak RF signal to a level suitable for further
processing.
(2) Mixing (Heterodyning):
The amplified RF signal is then mixed with the frequency of a local oscillator
(LO) in a mixer.
The mixer produces the sum and difference of the two input frequencies. The
desired frequency, called the intermediate frequency (IF), is chosen as the
fixed difference between the RF signal and the local oscillator frequency.
(3) Intermediate Frequency (IF) Selection:
The mixer output contains both the sum and difference frequencies.
A filter is used to select the difference frequency, which is the intermediate
frequency (IF).
Choosing a fixed IF simplifies the design of subsequent stages.
(4) IF Amplification:
The IF signal is then amplified by one or more stages of intermediate
frequency amplifiers.
Amplifying at a fixed IF simplifies the design and allows for better selectivity.
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Superheterodyne Outline Introduction Superheterodyne References
Superherodyne stages
(5) Demodulation:
The demodulator extracts the original modulating signal (audio, for example)
from the amplified IF signal. Demodulation can be accomplished using
various methods depending on the type of modulation used in the transmitter
(e.g., amplitude modulation (AM), frequency modulation (FM)).
(6) Audio Amplification
The demodulated audio signal is then passed through audio amplifiers to
increase its strength.
(7) Audio Output
The final stage involves converting the electrical audio signal into sound
waves using a speaker, providing the audio output that can be heard.
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Superheterodyne Outline Introduction Superheterodyne References
Advantages
The superheterodyne architecture provides several advantages,
including improved selectivity, sensitivity, and ease of tuning,
making it a widely used design in radio communication systems.
(1) Selectivity:
The use of a fixed intermediate frequency (IF) allows for the implementation
of highly selective filters. This helps in rejecting unwanted adjacent channel
interference and provides better selectivity, contributing to improved receiver
performance.
(2) Stability:
The local oscillator in a superheterodyne receiver is stabilized at a fixed
frequency, which enhances the overall stability of the receiver. This stability is
crucial for maintaining accurate tuning and avoiding frequency drift.
(3) Ease of Tuning:
Tuning in a superheterodyne receiver is simplified because the tuning is
performed at the fixed intermediate frequency. This makes it easier to design
tuning circuits and results in a more user-friendly tuning experience.
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Superheterodyne Outline Introduction Superheterodyne References
(4) Front-End Gain
The architecture allows for high gain in the RF (Radio Frequency) amplifier
stage since amplification is not required at the variable tuning frequency. This
contributes to better sensitivity in capturing weak signals.
(5) Efficient Amplification
The amplification of the intermediate frequency (IF) signal is done at a fixed
frequency, making it easier to design high-gain, selective amplifiers. This
contributes to improved signal-to-noise ratio and overall receiver performance.
(6) Front-End Gain
The architecture allows for high gain in the RF (Radio Frequency) amplifier
stage since amplification is not required at the variable tuning frequency. This
contributes to better sensitivity in capturing weak signals.
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Superheterodyne Outline Introduction Superheterodyne References
Modelling with Matlab/Simulink
Modeling a superheterodyne receiver using Simulink involves cre-
ating a block diagram that represents the different stages of the
receiver, such as RF amplification, mixing, filtering, and demodu-
lation. Here’s a simplified example of how you can model a super-
heterodyne receiver in Simulink:
(1) Open Simulink
Open MATLAB and then open Simulink by typing simulink in the MATLAB
command window.
(2) Create a New Model
In Simulink, go to the ”File” menu and choose ”New > Model” to create a
new Simulink model.
(3) Add Blocks
Drag and drop blocks from the Simulink library browser to the model canvas.
Use blocks such as Signal Source (for the RF input), RF Amplifier, Mixer,
Filter, IF Amplifier, Mixer (for the second local oscillator), and Demodulator.
(4) Connect Blocks
Connect the blocks using lines to represent signal flow. You can use the ”Add
Line” option in the Simulink toolbar.
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Superheterodyne Outline Introduction Superheterodyne References
Modelling with Matlab
(5) Parameterize Blocks
Double-click on each block to set its parameters. For example, specify the
gain of the RF amplifier, the frequency of the local oscillators, and the
characteristics of the filters.
(6) Scope Block for Visualization
Add a Scope block from the Simulink library to visualize the output of
different stages. Connect the output of relevant blocks to the Scope block.
(7) Simulation Settings
Set simulation parameters such as the simulation time, solver options, and
sample time.
(8) Run the Simulation
Click on the ”Run” button to start the simulation. The Scope block will
display the simulated output of your superheterodyne receiver.
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References Outline Introduction Superheterodyne References
Bibliography
q Pozar, D. M. (2011). Microwave Engineering. John Wiley & Sons.
q Armstrong, E. H.(1918). A Method of Reducing Disturbances in Radio
Signaling by a System of Frequency Modulation. Proceedings of the
Institute of Radio Engineers, 6(6), 671-679.
q Wikipedia. (2022). Superheterodyne Receiver. Retrieved from
https://en.wikipedia.org/wiki/Superheterodyne_receiver
q Proakis, J. G., & Salehi, M. (2008). Communication Systems
Engineering. Prentice Hall.
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Thank You and Query Please. . .
Bernardo Munguambe
 +258 848200065
 +258 871055827
 bernardo.munguambe@outlook.com
 www.youtube.com/pythonhub
bernardo.munguambe@outlook.com
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	Outline
	Introduction
	History
	Superheterodyne
	Definition
	Block diagram
	Superherodyne stages
	References