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OVERVIEW OF RADIO RECEIVERS FOR COMMUNICATION SYSTEMS
Khaytimbetova Shokhista Oybekovna
TUIT named after Muhammad al-Khorazmi,
Graduate student of the Department of
Television and Radio Broadcasting Systems
shokhistakhaytimbetova@gmail.com
https://doi.org/10.5281/zenodo.14264071
Abstract:
This article provides a comprehensive overview about radio receivers,
focusing on their classification, operating principles and quality indicators. Radio receivers
can be classified based on various criteria, including frequency range, modulation types,
applications and etc. The operating principles are explored in detail, comprising the processes
of signal reception, amplification, demodulation and others. In addition, key quality indicators
such as sensitivity, selectivity, interference immunity are analyzed to evaluate performance
and reliability of radio receivers. By understanding these aspects, users can make informed
decisions when choosing radio receivers for a variety of applications, from personal use to
professional broadcasting.
Keywords:
radio receiver, classification, operating principles, quality indicators,
sensitivity, selectivity, interference immunity.
I.INTRODUCTION.
A receiving device is an electronic or mechanical device designed to receive data, signal,
or energy. Radio receivers are widely used in many fields such as telecommunications, radio
broadcasting, television, radio relay and satellite communication systems. With the
development of technology, the demand for the efficiency of radio receivers has increased,
and different types of radio receivers have been created with different functions depending on
the field of application. This article aims to classify radio receivers, elucidate their operating
principles, and discuss the quality indicators that determine their performance.
II. RADIO RECEIVER CONCEPTS AND PERFORMANCE
Radio receiver – an electronic device that receives radio waves and converts them into a
usable form. Radio receivers are mainly used to receive radio broadcasts, television signals
and other types of radio waves. The main functions of the device are as follows:
-
capturing the electromagnetic field energy that carries the useful information;
-
amplifying the power of the useful radio signal;
-
detecting the radio signal;
-
amplifying the signal power and converting it into the message delivered to the receiver.
A.
Classification of radio receivers
Radio receivers can be classified based on various criteria, including their design,
functionality, and application. Below we explain in more detail the classification of radio
receivers:
-
According to the main functional task - professional and broadcasting radio receivers;
-
Radio communication receivers - local technological, internal-zone, trunk, international
and space communication receiving devices;
-
According to received signal types - analog and digital signal receivers;
-
By type of received information - radiotelephone, radiotelegraph, television, facsimile,
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voice transmission, data transmission and other receivers;
-
By modulation type - amplitude modulated (AM), frequency modulated (FM), phase
modulated (PM), pulse modulated (PM) and other types of radio receivers;
-
Depending on the wave range - myriametric waves (100...10 km), kilometer waves
(10...1 km), hectometer waves (1000...100 m), decameter waves (100...10 m), meter waves
(10…1 m), decimeter waves (100…10 cm), centimeter waves (10…1 cm), millimeter waves
(10…1 mm), decimeter waves (1...0.1 mm) and other wave receivers. Receivers that have
more than one of the above ranges are called multi-wave receivers.
-
By installation location – stationary, mobile, portable radio receiver;
-
By the method of supply – receivers which supplied from an alternating current
network, accumulator, galvanic or solar batteries, with universal supply;
-
According to the method of management and communication - manually controlled,
partially or fully automated, remote, mixed-control receivers;
-
According to the method of constructing the signal amplification tract before the
detector - direct amplification, direct detection, single, double or multiple frequency
conversion switchable super-heterodyne receivers.
B.
Principles of operation
Figure 1 shows a diagram demonstrating the basic functions of a radio receiver. It
consists of five functional parts. Below we will explore in detail the tasks that these functional
parts perform:
Fig. 1. A generalized scheme showing the functions of a radio receiver
In the
amplification-conversion tract
, useful signals are extracted from the mixture of
signals coming from antenna A and interferences that do not match the useful signal in terms
of frequency, and amplification of the useful signal necessary for the normal operation of
subsequent cascades is performed.
In the
information tract
, basic signal processing (demodulation) and interference
reduction is performed in order to extract the information from the signal. At the same time, it
is important to have high reliability of the allocated information. For this, an optimal filter,
post-detector processing circuits, frequency and phase automatic adjustment systems (FAS
and PAS) play a key role in the information tract structure. The task of FAS and PAS systems is
to demodulate the signal, as well as search for it by frequency and phase.
Local oscillator tract
changes its frequency or the frequency of the external base
generator and forms the type of frequency required for frequency conversion in the
amplification-conversion tract, signal processing devices in the information tract, and
subsequent systems.
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Adaptation, management and monitoring tract
performs manual, remote and
automated control of the receiver’s operation mode and the display of its work quality in
appropriate indicators.
In the
final device
, the energy of the isolated signal is used to create the required
output, that is, an acoustic, optical, mechanical effect.
The secondary power supply source
transforms the primary energy source into a
convenient form and path suitable for use in the radio receiver. This functional part allows for
voltage transformation, rectification, smoothing and stabilization to be carried out.
The considered structure scheme is general. Sometimes, some tracts may not be
available in radio receivers or perform a limited set of tasks. In this case, the simplified
structure of the receiving device and the limitation of the functions of individual tracts –
reduces the capabilities of the radio receiver. The greatest efficiency of receiving is achieved
by combining several radio receivers controlled on the basis of adaptive algorithms into a
radio receiving system. In such systems, each radio receiver receives the same signal in
different modes, and through computer control, processing of all received signals or selecting
the better received signal.
C.
Quality indicators
Several indicators that characterize the quality of radio receiver are available. From
these indicators, sensitivity, selectivity and interference immunity determine the
electromagnetic compatibility characteristic (EMC).
One of the main indicators of radio receiver is sensitivity, which measures the receiver’s
ability to receive weak signals normally. The sensitivity of the radio receiver is quantified by
the minimum value
E
A
of the electromotive force (EMF) in the antenna:
E
A
= 2
√𝑘𝑇∆𝐹
𝑅
𝑁𝑞
2
𝑟
𝐴
= 2
q
√𝑘𝑇∆𝐹
𝑅
𝑁𝑞
2
𝑟
𝐴
where, k=1.38 ∙ 10
-23
J/K – Boltzmann's constant; T - absolute temperature;
∆𝐹
𝑅
is the
bandwidth of the receiver; N is the noise coefficient of the receiver linear path;
r
A
is the
resistance of the antenna.
The selectivity of a radio receiver is the ability of the radio receiver to distinguish the
useful signal from interfering signals. It depends on the direction of arrival and the time of
impact of the useful and interfering signals, their polarization, amplitude, frequency, and
phase. The selectivity of a single signal is evaluated by the ratio of the level of the test signal at
the frequency of the interference to its value at the frequency of the useful signal, that is,
through the ratio of the corresponding gain coefficients, under constant tuning and the same
output voltage at the frequency of the interference:
S
e
= K
0
/ K(f)
where,
K
0
is the gain of the receiver at the resonance frequency f
0
; K(f) is the modulus of
the gain of the amplification-conversion tract over the voltage at an optional frequency f.
Interference immunity refers to the ability of a radio receiver to maintain the quality of
performance under conditions affected by interferences. When receiving discrete signals, the
resilience of the signal against interference is determined by the ratio of the number of
correctly received elementary signals M to the total number of transmitted elementary signals
N, expressed as P
u
= M/N.
An increase in the number of radio stations leads to a high rate of interference between
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radio stations. This interference leads to poor quality of the receiver. Research shows that the
use of wrong components and poor integrated circuits are the causes of this interference and
other receiver system deficiencies. As a result of modeling with the right components,
drawbacks are eliminated and quality indicators such as sensitivity and selectivity are
improved.
III. CONCLUSION
In conclusion, radio receivers play a pivotal role in modern communication systems,
offering a diverse range of functionalities and applications across various fields. The
classification of receivers based on frequency range, modulation type, and application enables
a better understanding of their capabilities and suitability for different purposes. By exploring
the operating principles, it becomes clear how these receivers convert electromagnetic waves
into usable audio or data signals, ensuring effective reception and processing. Additionally,
the quality indicators of radio receivers such as sensitivity, selectivity, and interference
immunity – are essential factors that determine the overall performance and user experience.
As technology continues to advance, radio receivers will remain integral to communication,
with ongoing innovations aimed at improving their efficiency and adaptability to new
transmission standards.
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Ezeagwu C.O, Ufoaroh S.U, Nnebe S.U and Nwalozie Gerald.C, “Modeling and
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