Presentation on radio communications and television. Invention of radio Principles of radio communication Television. The principle of radio communication is that the generated high frequency electric current created in the transmitting antenna causes a

Development of modern means of communication

Communication means - hardware and software used for generating, receiving, processing, storing, transmitting, delivering telecommunication messages or postal items, as well as other hardware and software used in providing communication services or ensuring the functioning of communication networks.

types of communications Wired (telephone, telegraph, etc.) Wireless, which, in turn, are divided into: radio (omnidirectional, narrow-directional, cellular and other radio systems), radio relay and space (satellite) devices, systems and complexes.

Communication means. The first is the emergence of oral speech. Scientists have identified five powerful impulses that accelerated the development of humanity that culture received during its existence:

The second is the invention of writing, which allowed a person to communicate with other people who are not in direct contact with him.

The third is the emergence and spread of printing.

The fourth is the emergence of electronic media, which provided everyone with the opportunity to become a direct witness and participant in the historical and cultural process taking place throughout the world. Radio Television

Fifth, according to many experts, is the emergence and development of the Internet as a new means of communication, which has provided ample opportunities in the forms and methods of receiving and transmitting information, as well as the implementation of many other functions.

Stages of development of communications. Creation of an optical telegraph - a device for transmitting information over long distances using light signals. This system was invented by the Frenchman Claude Chappe.

Communication by wire. The first electric telegraph was created in 1837 by English inventors: William Cook Charles Whetsone

Late model of the Cook and Whetstone telegraph. The signals activated arrows on the receiver, which pointed to different letters and thus conveyed a message.

Morse code In 1843, the American artist Samuel Morse invented a new telegraph code that replaced the Cook and Whetstone code. He developed dots and dashes for each letter.

And Charles Whetstone created a system in which the operator, using Morse code, typed messages on a long paper tape that entered the telegraph machine. At the other end of the line, the recorder was typing the received message onto another paper tape. Subsequently, the recorder was replaced by a signaling device, which converted dots and dashes into long and short sounds. Operators listened to the messages and recorded their translations.

Invention of the first telephone. Alexander Graham Bell (1847-1922) together with Thomas Watson (1854 - 1934) designed a device consisting of a transmitter (microphone) and a receiver (speaker). The microphone and speaker were designed in the same way. In the microphone, the speaker’s voice caused the membrane to vibrate, causing oscillations in the electric current . In the dynamics, current was applied to the membrane, causing it to vibrate and reproduce the sounds of the human voice. The first telephone conversation took place on March 10, 1876.

Invention of radio. The creator of the radio was Alexander Stepanovich Popov (1859-1906). On May 7, 1895, Popov demonstrated the radio receiver he had invented at a meeting of the physics department of the Russian Physico-Chemical Society. A type of wireless communication in which radio waves, freely propagating in space, are used as a signal carrier.

Satellite connection. Satellites are unmanned spacecraft flying in orbit around the Earth. They can transmit telephone conversations and television signals anywhere in the world. They also transmit weather and navigation information. In 1957, the USSR launched Sputnik 1, the world's first artificial Earth satellite.

In 1960, the Courier and Echo satellites were launched in the United States. They broadcast the first telephone conversations between the US and Europe. In 1962, Telstar, the first television satellite, entered orbit in the United States.

Fiber-optic communication lines. Fiber-optic communication lines (FOCL) are currently considered the most advanced physical medium for transmitting information. Data transmission in optical fiber is based on the effect of total internal reflection. Thus, the optical signal transmitted by the laser on one side is received on the other, much distant side. Today, a huge number of backbone fiber optic rings, intracity and even intraoffice, have been built and are being built.

Laser communication system A rather interesting solution for high-quality and fast network communication was developed by the German company Laser2000. The two presented models look like the most ordinary video cameras and are designed for communication between offices, within offices and along corridors. Simply put, instead of laying an optical cable, you just need to install the inventions from Laser2000. However, in fact, these are not video cameras, but two transmitters that communicate with each other via laser radiation. Let us recall that a laser, unlike ordinary light, for example, lamp light, is characterized by monochromaticity and coherence, that is, laser beams always have the same wavelength and are slightly scattered.

Links to sources of information and images: www.digimedia.ru/articles/svyaz/setevye-tehnologii/istoriya/faks-istoriya-ofisnogo-vorchuna/ http://ru.wikipedia.org/wiki/%D0%9F%D0% BE%D0%BF%D0%BE%D0%B2,_%D0%90%D0%BB%D0%B5%D0%BA%D1%81%D0%B0%D0%BD%D0%B4%D1% 80_%D0%A1%D1%82%D0%B5%D0%BF%D0%B0%D0%BD%D0%BE%D0%B2%D0%B8%D1%87 http://geniusweb.ru/? feed=rss2 ru.wikipedia.org/wiki/ Radio http://www.5ka.ru/88/19722/1.html

Transferring an imageTo transfer an image, you must first
convert into electrical signals. At the station
from which the signal is transmitted, it is converted into
sequence of electrical impulses.
Then these signals modulate the oscillations
high frequency.

Television and its development

Television and its development
Development of communications
carried out in full
on the move. Even 20 years ago
not in every apartment
one could meet
home wired
telephone. And now it's already
you won't surprise anyone
availability of mobile
the child's phone. About
satellite television
may not even be mentioned.

Iconoscope

To convert
images in
electrical signal
use the device
called an iconoscope.
Iconoscope is not
the only way
transformation
images to stream
electrical impulses.

Stages of development of communications

English scientist James Maxwell in 1864
theoretically predicted the existence
electromagnetic waves.
1887 experimentally in Berlin
University was discovered by Heinrich Hertz.
May 7, 1895 A.S. Popov invented radio.
In 1901, the Italian engineer G. Marconi for the first time
made radio communications across the Atlantic Ocean.
B.L. Rosing May 9, 1911 electronic television.
30 years V.K. Zvorykin invented the first transmitter
iconoscope tube.

Modern directions in the development of communications

Radio communication
Telephone communications
Television communication
cellular
Internet
Space communications
Phototelegraph (Fax)
Video telephony
Telegraph communication

Radio communication

– transmission and reception of information using
radio waves propagating in space without
wires

Types of radio communication.

Radiotelegraph
Radiotelephone
Broadcasting
A television.

Space communications

SPACE COMMUNICATIONS, radio communications or optical
(laser) communication carried out between
ground receiving and transmitting stations and
spacecraft, between several
ground stations via communication satellites,
between several spacecraft.

Phototelegraph

Phototelegraph, common abbreviation
fax name
(phototelegraph communication).
Type of communication for sending and receiving data
images (manuscripts, tables,
drawings, drawings, etc.).
A device that performs such communication.

The first phototelegraph

At the beginning of the century, German
was created by physicist Korn
phototelegraph,
which is nothing
not fundamentally different
from modern drums
scanners. (In the picture on the right
the telegraph diagram is shown
Corna and portrait
inventor,
scanned and
transmitted over a distance
more than 1000 km November 6, 1906
of the year).

Shelford Bidwell
Bidwell), British physicist,
invented the "scanning"
phototelegraph." For
image transmission
(diagrams, maps and
photos) in the system
material used
selenium and electrical
signals.

Video telephony

Personal video telephone
communication on UMTS equipment
The latest telephone models
devices have
attractive design,
wide selection of accessories,
wide functionality,
support technology
Bluetooth and wideband-ready audio, as well as XML integration with
any corporate
applications

Types of signal transmission line

Two wire line
Electrical cable
Metric waveguide
Dielectric waveguide
Radio relay line
Beam line
Fiber optic line
Laser communication

Fiber optic communication lines

Fiber optic communication lines (FOCL) are currently considered
the most perfect physical medium for transmitting information.
Data transmission in optical fiber is based on the effect of full
internal reflection. Thus, the optical signal transmitted
laser on one side, received on the other, significantly distant
side. To date, a huge
number of backbone fiber optic rings, intracity and
even in-office ones. And this number will constantly grow.

FOCLs use electromagnetic waves of optical
range. Recall that visible optical radiation lies in
wavelength range 380...760 nm. Practical application in
FOCL received the infrared range, i.e. radiation with length
waves above 760 nm.
The principle of propagation of optical radiation along
optical fiber (OF) is based on reflection from the boundary of media
with different refractive indices (Fig. 5.7). Optical
the fiber is made of quartz glass in the form of cylinders with
combined axes and different coefficients
refraction. The inner cylinder is called the OB core, and
the outer layer is the OM shell.

Laser communication system

Quite an interesting solution for
high-quality and fast network communication
developed by a German company
Laser2000. Two models presented
they look like the most common ones
video cameras and are designed for communication
between offices, within offices and across
corridors. Simply put, instead of
to lay an optical cable,
you just need to install the inventions
from Laser2000. However, in fact,
these are not video cameras, but two transmitters,
which carry out among themselves
communication via laser radiation.
Let us recall that a laser, unlike
ordinary light, for example, lamp,
characterized by monochromaticity and
coherence, that is, laser beams
always have the same length
waves and dissipate little.

For the first time, laser communication was carried out between a satellite and an aircraft 12/25/06, Mon, 00:28, Moscow time

The French company Astrium is the first in the world
demonstrated successful communication
laser beam between the satellite and the aircraft.
During testing of a laser communication system,
held in early December 2006, contact on
at a distance of almost 40 thousand km was carried out
twice - once the Mystere 20 aircraft was
at an altitude of 6 thousand m, another time flight altitude
was 10 thousand m. The aircraft speed was
about 500 km/h, data transmission speed
laser beam - 50 Mb/s. Data was transferred to
geostationary telecommunications satellite Lesson 2/1
Radio Basics
Study questions
1. Classification of radio waves.
2. Propagation of radio waves of various ranges.

Literature

Krukhmalev
IN.
AND.
And
etc.
Basics
construction
telecommunication systems and networks. Textbook. HotlineTelecom, M.: 2008. 2000у.
2. Motorkin V.A. and others. Practical foundations of radio communications. Educational
allowance. Khimki, FGOU VPO AGZ EMERCOM of Russia, 2011. 2476k.
3. Papkov S.V. and others. Terms and definitions of communication in the Ministry of Emergency Situations of Russia. –
Novogorsk: AGZ. 2011. 2871k.
4. Motorkin V.A. etc. A course of lectures on the discipline (specialty
– protection in emergencies) “Communication and warning systems” (textbook) –
Khimki: AGZ EMERCOM of Russia - 2011. 2673k.
Golovin O.V. and others. Radio communication - M.: Hotline - Telecom,
2003. pp. 47-60.
Nosov M.V. Radio communication systems - N.: AGZ, 1997.
Papkov S.V., Alekseenko M.V. Basics of organizing radio communications
in RSChS - N.: AGZ, 2003. P. 3-10.
1.
03.02.2017
2

1st study question
Classification of radio waves
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3

300
m
f MHz
Wave Range - Frequency Range
Power frequency EM waves
Radio band:
Extra-long (ULF) – Ultra-low (ELF)
Long (LW) – Low (LF)
Middle (MW) – Middle (Mid)
Short (HF) – High (HF)
Ultra short (VHF): Very high (VHF),
Ultra high (UHF),
Ultra high (microwave)
Millimeter (MMW)
Decimillimeter (DMMV)
Optical range:
Infrared rays
Visible light
Ultra-violet rays
300
f MHz
m
Wavelength (m)
-105
Frequency (MHz)
(0-3) 10-3
105-104
104-103
103-102
102-101
101-100
100-10-1
10-1-10-2
10-2-10-3
10-3-10-4
(3-30) 10-3
(3-30) 10-2
(3-30)-1
(3-30)0
(3-30)1
(3-30) 102
(3-30) 103
(3-30) 104
(3-30) 105
3.5 10-4-7.5 10-7
7.5 10-7-4 10-7
4 10-7-5 10-9
8.6 106-4 108
4 108-7.5 108
7.5 108-6 1010
X-rays
10-8-10-12
3 1010-3 1012
- rays
10-12-10-22
3 1012-3 1024
03.02.2017
6

Type of radio waves
Type of radio waves
Range
radio waves
(wavelength)
Myriameter
Extra long
(ADV)
10...100 km
4
3...30 kHz
Very low
(VLF)
Kilometer
Long (LW)
1...10 km
5
30...300 kHz
Low (LF)
Hectometric
Medium (SV)
100…1000 m
6
300...3000 kHz
Mids (mids)
Decameter
Short (HF)
10...100 m
7
3...30 MHz
Treble (HF)
Meter
1...10 m
8
30...300 MHz
Very high
(VHF)
decimeter
10...100 cm
9
300...3000 MHz
Ultra high
(UHF)
1...10 cm
10
3...30 GHz
Extra high
(microwave)
Millimeter
1...10 mm
11
30...300 GHz
Extremely high
(EHF)
decimmillimeter
e
0.1...1 mm
12
300...3000 GHz
Hyperhigh (HHF)
Centimeter
Ultra short
(VHF)
№
range
on
Range
frequencies
Type of radio frequencies

2nd study question
Propagation of radio waves of various ranges
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8

Types of radio wave propagation:
along the earth's surface;
with radiation into the upper layers of the atmosphere and from them back to
surface of the Earth;
with reception from Earth and return transmission to Earth via
space relays.
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Rice. Ideal radio wave propagation
9

03.02.2017
10

Rice. Radio wave propagation paths

Type of radio waves
Basic methods
distribution
radio waves
Communication range, km
Myriameter and
kilometer
(extra long and
long)
Diffraction. Reflection
from the Earth and the ionosphere
Up to a thousand. Thousands
Hectometric
(average)
Diffraction.
Refraction in
ionosphere
Hundreds. Thousands
Decameter
(short)
Refraction in
ionosphere and reflection
from the earth
Thousands
Meter and more
short
Free
distribution and
reflection from the Earth.
Troposphere scattering
Dozens. Hundreds

Peculiarities of propagation of waves in the MF, LF and VLF ranges
Waves with lengths from 1 to 10 km, low frequency range, and even longer ones,
exceed the size of soil unevenness and obstacles, and when
propagation, diffraction is noticeably manifested (bending around the earth's surface,
etc).
The waves then propagate in free space rectilinearly,
the formation of a “dead zone” is possible. As the frequency decreases, energy loss
waves decrease when absorbed by the soil. Therefore, LF and VLF with the same
Radiation powers travel over longer distances than short ones.
At a power of tens of kW, the field strength of surface waves
sufficient to receive signals over distances of thousands of kilometers.
Spatial waves of these ranges, when propagating in
direction of the ionosphere, are reflected and return to the Earth. Happening here
reflection from the earth's surface, etc. This distribution is called
multi-hop.
Long-distance ionospheric wave propagation has negative consequences for radio communications.
consequences if superficial and
spatial waves - multipath. At point B, addition occurs
waves - interference.
VLF waves have the ability to penetrate a wide range of
depth into the surface layer of the earth and even into sea water. It does
02/03/2017 VLF communications with underground and underwater objects. 14
possible

Type of radio waves
Basic methods
radio wave propagation
Communication range, km
Myriameter and
kilometer (extra-long)
and long)
Diffraction. Reflection from
Earth and ionosphere
Up to a thousand. Thousands
Hectometric (average)
Diffraction. Refraction in
ionosphere
Hundreds. Thousands
Decameter (short)
Refraction in the ionosphere and
reflection from the Earth
Thousands
Meter and shorter
Free distribution and
reflection from the Earth.
Troposphere scattering
Dozens. Hundreds

Losses in the soil increase with increasing frequency, the radio communication range with
using surface waves in the MF is less than in the LF (1500 km).
Spatial waves are strongly absorbed in the ionosphere during the day, and at night
radio reception at distances of 2-3 thousand km. Between the radio reception area
surface waves, and a more distant reception area of spatial waves
there is a territory in which the intensity of both waves has
same order of magnitude. Therefore, deep interference is possible
fading and radio communication turns out to be unstable.
HF Wave Propagation
Due to significant energy losses in the soil, long-distance communication by surface
waves in the HF range rarely exceed 100 km. Ionospheric propagation
waves, improves with increasing frequency due to reduced losses.
The reflection of waves from a smooth surface turns out to be specular: angle
incidence is equal to the angle of reflection. The ionosphere is heterogeneous and uneven, therefore
waves are reflected in different directions, i.e. scattered
reflection. In Fig. this property of reflected waves forming is shown
relatively wide beam 1. Between the surface propagation zone
waves and the territory into which spatial waves arrive is formed
“dead zone” Some of the wave energy may not be reflected to the Earth at all, but
propagates in the layer as in a conductor (the trajectory is designated 2). If the waves
experience insufficient refraction in the ionized layer, then they go into
03.02.2017
17
transatmospheric
space; This case corresponds to trajectory 3.

Rice. Path of radio waves in the ionosphere
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Rice. Addition of radio waves due to multipath propagation
19

Propagation of VHF, UHF and Microwave Bands
Microwave waves travel like light
straight forward. Diffraction in these ranges is weak. Waves emitted under
angle to the earth's surface, go into the extra-atmospheric space almost
without changing the trajectory, this property made it possible to successfully apply
microwaves for satellite communications.
The inability of waves in these ranges to bend around the surface requires
radio communications ensuring geometric visibility between the transmitting and
receiving antennas (Fig. a, b).
Since the waves are reflected from the earth's surface, at the point of reception
interference of beams is possible (Fig. c); and interference arises
fading and distortion of transmitted messages.
At relatively high power, the communication range is significantly
exceeds normal. Unevenness of the earth's surface and differences in soils,
vegetation cover, the presence of rivers and reservoirs, settlements, engineering
structures, etc. affect the lower layers of air, leading to the formation of
atmosphere of zones with different temperatures and humidity, local flows
air, etc. In these zones, at altitudes up to several kilometers, occurs
wave scattering, as shown schematically in Fig. d. In this case, part
wave energy reaches points distant from the transmitting antenna by
distance,
5-10 times greater than the geometric visibility range.21
03.02.2017

Rice. Features of propagation of VHF radio waves
03.02.2017
Rice. Long-distance propagation using an "atmospheric waveguide"
22

Irregularities also exist in the ionosphere (uneven concentration
free electrons), where ionospheric wave scattering also occurs. At
high power dissipation ensures communication at distances of 1-2 thousand km.
Other types of long-range UHF and microwave propagation appear when
formation in the atmosphere of extended and clearly defined heterogeneities in
as a layer. The waves propagate inside the layer, reflecting from its boundaries, or
between the ground surface and the lower boundary of the layer. These two cases
are schematically shown in Fig. d. Another type of long-range propagation is reflection from meteor trails. Due to the variability of the meteor process
propagation is used only in special radio communication systems.
In addition to the received radio signal, the receiver is affected by outsiders
vibrations of various origins - radio interference, can cause distortion
received messages: during radiotelephone communication (in the form of clicks, crackling and
noise that impairs the intelligibility of speech messages); telegraph apparatus
prints incorrect characters; on the fax machine form there are extra
lines that spoil the image:
Extraneous radio signals.
Spurious emissions from radio transmitting devices.
Atmospherics.
Industrial interference.
Internal noise of the radio receiver (fluctuation noise).
03.02.2017
23
Space
noises.

Principles of Radio Communication

Electromagnetic waves
spread over huge
distances, that's why they are used
for transmitting sound (radio waves) and
images (television).
Occurrence condition
electromagnetic wave is
the presence of acceleration in moving
charges!
Radio communication is transmission
information using
electromagnetic waves.

The microphone converts mechanical
oscillations into electromagnetic oscillations
sound frequency.

After modulation, the wave is ready for transmission.
Possessing a high frequency, it can be transmitted to
space.
And it carries audio frequency information.

In the receiver it is necessary to isolate from high-frequency
modulated oscillations of an audio frequency signal, i.e.
carry out detection

Principles of Radio Communication

Converts electromagnetic vibrations into
mechanical vibrations of sound frequency

James Maxwell
English physicist James Clerk
Maxwell developed
electromagnetic theory
fields and predicted
existence
electromagnetic waves.

Heinrich Hertz
In 1887, G. Hertz for the first time
got electromagnetic
waves
and investigated their properties.
He measured the lengths of these
waves and determined the speed
their distribution.

To obtain electromagnetic waves Heinrich Hertz
used a simple device called
Hertz vibrator.
This device is an open
oscillatory circuit.

Electromagnetic waves were recorded from
using a receiving resonator in which
current oscillations are excited.

Alexander Stepanovich Popov
A.S.Popov applied
electromagnetic waves for
radio communications.
Using a coherer, relay,
electric bell Popov
created a device for detecting
and registration of electrical
vibrations - radio receiver.

Popov receiver circuit,

Heinrich Hertz

The principle of radio communication is that
created high frequency electric current,
created in the transmitting antenna, calls in
the surrounding space is rapidly changing
electromagnetic field, which
propagates in the form of electromagnetic
waves.

To produce electromagnetic waves, Heinrich Hertz used a simple device called a Hertz vibrator. This device is

Oscillations
high frequency CARRIER frequency
Fluctuation chart
audio frequency,
those.
MODULATING
fluctuations
Schedule
MODULATED
by amplitude
fluctuations

Electromagnetic waves were recorded using a receiving resonator in which current oscillations were excited.

Detection.

Invention of the radio

Radio communication principle:
In the transmitting antenna it is created
alternating electric current
high frequency, which causes
surrounding space
rapidly changing electromagnetic
field propagating in the form
electromagnetic wave.
Reaching the receiving antenna,
electromagnetic wave causes in it
alternating current of the same frequency, at
which the transmitter operates.

A.S. Popov used electromagnetic waves for radio communication. Using a coherer, a relay, and an electric bell, Popov created a device for detecting

To implement
radio communications
use oscillations
high frequency,
intensively
emitted by the antenna
(produced
generator).
To transmit sound
these high frequency
vibrations change -
modulate with
with help
electrical
fluctuations low
frequencies.
MODULATION –
amplitude change
high frequency
fluctuations
in accordance with
sound frequency.

Popov receiver circuit,

In the receiver of modulated oscillations
high frequencies highlight low frequencies
fluctuations. This process is called
detection.
DETECTION – conversion process
high frequency signal into a low frequency signal.
Received after
signal detection
corresponds to that
sound signal, which
acted on the microphone
transmitter. After
amplification of low vibration
frequencies can be
turned into sound.

The principle of radio communication is that the generated high frequency electric current created in the transmitting antenna causes a

Radio receiver device
Main
element
radio receiver
Popova served
coherer - tube with
electrodes and
metal
sawdust.
Invented by Edouard Branly
in 1891

The simplest radio receiver

Detection.

Transmitting device diagram

Receiver circuit diagram

Application of radio waves
radio waves,
TV,
space communication,
radar.

Radio waves

Radio receiver device

A television

The simplest radio receiver

Space communications

May 7 – RADIO Day

Radar
Detection and
definition
locations
various
objects using
radio waves

Transmitting device diagram

Radar (from the Latin words “radio” to radiate and “lokatio” – location)
Radar – detection and accuracy
determining the position of objects with
using radio waves.

Receiver circuit diagram

History of radar development
A. S. Popov in 1897 during experiments on radio communication between ships
discovered the phenomenon of reflection of radio waves from the side of the ship. Radio transmitter
was installed on the upper bridge of the transport “Europe”, which was at anchor,
and the radio receiver is on the cruiser Africa. During experiments, when between
cruiser "Lieutenant Ilyin" was hit by ships, instrument interaction
stopped until the ships left the same straight line
In September 1922 in the USA, H. Taylor and L. Young conducted experiments on radio communications on
decameter waves (3-30 MHz) across the Potomac River. At this time, I passed along the river
ship, and the connection was interrupted - which gave them the idea of using
radio waves to detect moving objects.
In 1930, Young and his colleague Highland discovered the reflection of radio waves from
airplane. Soon after these observations they developed a method of using
radio echo for aircraft detection.

Application of radio waves

History of the creation of radar (RADAR - abbreviation for Radio Detection
And Ranging, i.e. radio detection and ranging)
Robert Watson-Watt (1892 - 1973)
Scottish physicist Robert Watson-Watt was the first to build in 1935
radar installation capable of detecting aircraft on
distance 64 km. This system played a huge role in protecting
England from German air raids during World War II
war. In the USSR, the first experiments in radio detection of aircraft
were carried out in 1934. Industrial production of the first radars,
adopted for service, was launched in 1939. (Yu.B.Kobzarev).

Radio waves

Radar is based on the phenomenon of reflection of radio waves from
various objects.
Noticeable reflection is possible from objects if their linear
dimensions exceed the length of the electromagnetic wave. That's why
radars
8
11
operate in the microwave range (10 -10 Hz). As well as the power of the emitted signal
~ω4.

A television

Radar antenna
Antennas in the form of parabolic antennas are used for radar
metal mirrors, in the focus of which the emitting
dipole. Due to the interference of waves, a highly directional
radiation. It can rotate and change its angle, sending
radio waves in different directions. Same antenna
alternately automatically with the pulse frequency is connected to
transmitter, then to the receiver.

A television:

Space communications

Radar operation
The transmitter produces short pulses of alternating current microwave
(pulse duration 10-6 s, the interval between them is 1000 times longer),
which through the antenna switch enter the antenna and are radiated.
In the intervals between emissions, the antenna receives reflected from the object
signal, while connecting to the receiver input. The receiver performs
amplification and processing of the received signal. In the simplest case
the resulting signal is fed to a beam tube (screen), which shows
image synchronized with antenna movement. Modern radar
includes a computer that processes the signals received by the antenna and
displays them on the screen in the form of digital and text information.

Radar

Determining the distance to an object
ct
S
2
c 3,108 m/s
S – distance to the object,
t – propagation time
radio pulse
to the object and
back
Knowing the orientation of the antenna during target detection, they determine it
coordinates. By changing these coordinates over time, we determine
target speed and calculate its trajectory.

Radar reconnaissance depth
Minimum distance at which a target can be detected (time
propagation of the signal back and forth must
be greater than or equal to the pulse duration)
lmin
c
2
-pulse duration
Maximum distance at which a target can be detected
(the signal propagation time there and back is not
must be longer than the pulse repetition period)
lmax
cT
2
T-period of pulse repetition

Application of radar
Aviation
Based on signals on radar screens, airport dispatchers
control the movement of aircraft along air routes, and pilots
accurately determine flight altitude and terrain contours, can
navigate at night and in difficult weather conditions.

The main application of radar is air defense.
The main task is to observe
by air
space,
discover and lead
purpose, in case
necessity
aim air defense at her
and aviation.

Cruise missile (single launch unmanned aerial vehicle)
launch)
Full control of the rocket in flight
autonomous. The principle of operation of its system
navigation is based on mapping
terrain of a specific area
finding a rocket with reference maps
terrain along its flight route,
pre-stored in memory
onboard control system.
The radio altimeter ensures flight
preset route in mode
bending around the terrain due to precise
maintaining flight altitude: above the sea no more than 20 m, above land - from 50 to 150 m (with
approaching the target - decrease to 20 m).
Correction of the rocket flight path by
marching section is carried out along
satellite navigation subsystem data
and relief correction subsystems
terrain.

The plane is invisible
Stealth technology reduces the likelihood that an aircraft will be
positioned by the enemy. The surface of the aircraft is assembled from
several thousand flat triangles made of
material that absorbs radio waves well. locator beam,
falling on it, dissipates, i.e. the reflected signal is not
returns to the point from where it came (to the radar
enemy stations).

Radar for measuring vehicle speed
One of the important methods for reducing accidents is
control of vehicle speed limits
roads. The first civilian radars to measure
American police traffic speed
were already in use at the end of World War II. Now they
are used in all developed countries.

Radar operation

Weather radars for forecasting
weather. Radar detection objects can
be
clouds,
precipitation,
thunderstorms
foci.
Can
forecast hail, showers, squalls.

Application in space
Radars are used in space research
for flight control
and satellite tracking,
interplanetary
stations,
at
docking
ships.
Radar detection of planets has made it possible to clarify their parameters
(for example, distance from the Earth and rotation speed), state
atmosphere, carry out surface mapping.

Description of the presentation by individual slides:

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Principles of radio communications and television Physics teacher MBOU "Ust-Mayskaya Secondary School" Ivanova Nadezhda Alekseevna

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“He should be ashamed who uses the wonders of science embodied in an ordinary radio receiver, and at the same time values them as little as a cow appreciates the wonders of botany that she chews.” A. Einstein

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What is an electromagnetic wave? How are electromagnetic waves different from each other? What do all EM waves have in common? What is the name of the system in which electromagnetic waves are received? What does the intrinsic period of an oscillatory circuit depend on? How can it be changed? Updating of reference knowledge

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Heinrich Rudolf Hertz 02/22/1857 - 01/01/1894 1888 Experimental registration of electromagnetic waves He used dipoles or vibrators named after Hertz as oscillatory circuits. Two rods with balls, between which small gaps were left. A fairly high voltage was supplied to the balls from an induction coil. A spark jumped between them, and an electromagnetic field arose in space, and, consequently, an electromagnetic wave. To record electromagnetic waves, Hertz used a second vibrator, called a resonator, which had the same frequency of natural oscillations as the radiating vibrator, i.e., tuned in resonance with the vibrator. When electromagnetic waves reached the resonator, an electric spark jumped in its gap. With the help of the described vibrator, Hertz reached frequencies of the order of 100 MHz. Hertz's experiments showed that using electromagnetic waves it is possible to send and receive signals, but this is only possible at a short distance within the table. And Hertz did not see the practical value of using electromagnetic waves and himself denied: “Their use in practice is impossible!” Hertz's experiments, described in 1888, interested physicists around the world.

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Invention of radio In Russia, Alexander Stepanovich Popov, a teacher of officer courses, was one of the first to study electromagnetic waves. Alexander Stepanovich Popov 03/16/1859 - 01/13/1906 In Russia, Alexander Stepanovich Popov, a teacher of officer courses in Kronstadt, was one of the first to study electromagnetic waves. Interested in this discovery, A.S. Popov, with his characteristic energy, began a detailed study of electromagnetic waves. Unlike most scientists who saw in these waves only a curious physical phenomenon, A.S. Popov was able to appreciate their practical significance.

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Invention of the radio “The human body does not have a sensory organ that would notice electromagnetic waves in the ether; If a device could be invented that would replace our electromagnetic senses, it could be used in transmitting signals over a distance.”

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Invention of radio A special feature of Popov's receiver was the method of recording waves, for which he used not a spark, but a special device - a coherer. To increase the sensitivity of the receiver, Popov used the phenomenon of resonance and also invented a highly raised receiving antenna. Another feature of Popov’s receiver was the method of recording waves, for which Popov used not a spark, but a special device - a coherer (from Latin - “coherence” - “coupling”), recently invented by Branly and used for laboratory experiments. The coherer was a glass tube with small metal filings inside; wires were inserted into both ends of the tube in contact with the filings.

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Invention of the radio The incoming electromagnetic wave created a high-frequency alternating current in the coherer. Tiny sparks jumped between the sawdust and sintered the sawdust. As a result, the resistance of the coherer dropped sharply (in the experiments of A.S. Popov from 100,000 to 1000 - 500 Ohms, that is, 100-200 times). It was possible to return the device to high resistance again by shaking it. To ensure automatic reception for wireless communication, A.S. Popov used a bell device to shake the coherer after receiving a signal. The operation of the device was based on the effect of electrical discharges on metal powders. Under normal conditions, the coherer had high resistance, since the sawdust had poor contact with each other. The incoming electromagnetic wave created a high-frequency alternating current in the coherer. Tiny sparks jumped between the sawdust and sintered the sawdust. As a result, the resistance of the coherer dropped sharply (in the experiments of A.S. Popov from 100,000 to 1000 - 500 Ohms, that is, 100-200 times). It was possible to return the device to high resistance again by shaking it. To ensure automatic reception for wireless communication, A.S. Popov used a bell device to shake the coherer after receiving a signal.

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May 7, 1895 Invention of radio by A.S. Popov set to work on the technical implementation of his idea. Finally such a device was created. On May 7, 1895, in a crowded hall at a meeting of the Russian Physico-Chemical Society A.S. Popov reported on the first results of his work and demonstrated the radio receiver he had designed. This day - May 7 - the birthday of radio is celebrated in our country as a national holiday.

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The first radiogram Alexander Stepanovich Popov in 1896, using a transmitter and receiver designed by him, transmitted two words “Heinrich Hertz” using an attached telegraph apparatus.

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The invention of radio Popov's goal was to build a device for transmitting signals over long distances. A.S. Popov continued to persistently improve the receiving equipment. His immediate goal was to build a device for transmitting signals over long distances.

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Invention of radio While conducting exercises on the Black Sea, Alexander Stepanovich reached a distance of more than 20 km. Two years later, in 1901, radio transmission was carried out over a distance of 150 km. Initially, radio communication was established at a distance of 250 m. Popov soon achieved a communication range of more than 600 m.

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Invention of radio With the participation of A. S. Popov, the introduction of radio communications began in the Russian Navy and Army. Signal recording methods have also changed significantly. In parallel with the call, a telegraph apparatus was turned on, which made it possible to automatically record signals. In 1899, the possibility of receiving signals using a telephone was discovered. At the beginning of 1900, radio communications were successfully used during rescue operations in the Gulf of Finland. With the participation of A. S. Popov, the introduction of radio communications began in the Russian Navy and Army.

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Invention of the radio In 1900, the radio station telegraphed about the stranded battleship Admiral General Apraksin. Continuing experiments and improving instruments, A.S. Popov slowly but surely increased the range of radio communications. 5 years after the construction of the first receiver, a regular wireless communication line began to operate at a distance of 40 km. The fate of Popov's invention in Russia was not as swift as the fate of radio in the West. In response to a request for radio funding, the Minister of the Navy wrote: “I don’t allow money to be spent on such a chimera.” But already in 1900, a radio station on the island of Gogland, built according to Popov’s instructions, telegraphed about the stranded battleship Admiral General Apraksin.

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The Invention of Radio In 1912, radio helped save hundreds of people from the Titanic. In 1912, radio helped save hundreds of people from the Titanic, which managed to send an SOS signal. Radio, which began its practical history by saving people, became a new progressive form of communication in the 20th century.

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Invention of radio Abroad, the improvement of such devices was carried out by a company organized by the Italian engineer Guglielmo Marconi. Abroad, the improvement of such devices was carried out by a company organized by the Italian engineer G. Marconi. Experiments carried out on a large scale made it possible to carry out radiotelegraph transmission across the Atlantic Ocean. The end result of his work was simply a synthesis of all the latest achievements in the field of radio. The receiver was based on Popov’s device, which Marconi slightly improved by adding a vacuum coherer and choking coils. And as a transmitter I used a Hertz generator, slightly modified by Rigi. Marconi's main success was that he was the first to patent his invention and began to benefit from it. He immediately founded a joint-stock company and began creating and distributing his devices on an industrial scale. In 1909, Marconi was awarded the Nobel Prize in Physics "in recognition of their services to the development of wireless telegraphy." The main merit was that he was able to combine the knowledge of his predecessors and translate it into a device suitable for practical use. Source: http://www.calend.ru/person/477/ © Calend.ru

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Block diagram of a radio transmitter Modulation is the process of changing the amplitude of high-frequency oscillations with a frequency equal to the frequency of the sound signal. Sound vibrations are converted by a microphone into electrical current vibrations. However, electromagnetic waves of “sound” frequencies are emitted with such low power that they cannot be transmitted over significant distances. Since the radiated power increases rapidly with frequency (P~ν^4), waves with high frequencies are used for transmission. Such waves are emitted by oscillations in a high-frequency electrical oscillation generator. Under the influence of high-frequency modulated oscillations, high-frequency alternating current appears in the transmitting antenna. This current generates an electromagnetic field in the space around the antenna, which propagates in the form of electromagnetic waves and reaches the antennas of receiving devices.

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Block diagram of a radio receiver Detection is the inverse process of modulation. Another principle is the reverse process - detection. When receiving radio signals, it is necessary to filter out low-frequency audio vibrations from the modulated signal received by the antenna of the receiver.

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Radio receiver A.S. Popova “I am proud that I was born Russian. And if not my contemporaries, then perhaps our descendants will understand how great my devotion to our homeland is and how happy I am that a new means of communication has been discovered not abroad, but in Russia.” Working under difficult conditions of the tsarist regime, without material support, Popov did not accept any of the tempting offers from foreign companies to sell them patents for his inventions. He resolutely rejected them. Here are his words: “I am proud that I was born Russian. And if not my contemporaries, then perhaps our descendants will understand how great my devotion to our homeland is and how happy I am that a new means of communication has been discovered not abroad, but in Russia " Even after gaining great fame, Popov retained all the main traits of his character: modesty, attention to other people’s opinions, willingness to meet everyone halfway and help those in need of help as much as possible.

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Radio communication Radio communication is the transmission and reception of sound information using electromagnetic waves with a frequency from 0.1 to 1000 MHz. Radio communication lines are used for radiotelephone communications, transmission of telegrams, facsimiles (faxes), radio broadcasting and television programs

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Application of radio waves The lengths of electromagnetic waves in the radio range range from 100 km to 0.001 m (1 mm). Television, radar, satellite television, and cellular communications have entered our daily lives. Here is a table Classification of radio waves by range.

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Television Television is the transmission of images of objects and sound over a distance.

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Diagram of a television transmitter and receiver The process of transmitting an image over a distance is basically similar to radiotelephony. It begins by converting an optical image into an electrical signal. This transformation occurs in the transmitting television camera (Fig.). The resulting electrical signal, after amplification, modulates high-frequency oscillations of the carrier frequency. The modulated oscillations are amplified and fed to the transmitting antenna. An alternating electromagnetic field is created around the antenna, propagating in space in the form of electromagnetic waves. In a television receiver, the received electromagnetic oscillations are amplified, detected, amplified again and fed to the control electrode of the receiving television tube, which converts the electrical signal into a visible image.

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Satellite of the "Rainbow" series "Molniya" series: elongated orbit, T= 12 hours. "Rainbow" series: R = 36000 km, T= 24 hours. Artificial communication satellites The successes of the USSR (second half of the 20th century) in space technology made it possible to use artificial Earth satellites for placing radio and television relay stations on them. On April 23, 1965, the first Soviet communications satellite, Molniya-1, was launched. The orbit of this satellite is a highly elongated ellipse (Fig.). Its orbital period is 12 hours. The Molniya satellite is an extraterrestrial relay in the Orbit network. The Orbita network works as follows. The ground transmitting station, using a radio transmitter with a power of several kilowatts through a highly directional parabolic antenna, emits a signal to the Molniya communications satellite. The received signal is amplified and relayed to Earth using a special transmitter. The width of the radiation pattern of the satellite antenna is such that the beam of electromagnetic waves emitted by it covers the entire surface of the Earth “visible” from the satellite. In addition to the Molniya satellites, the Raduga series satellites are used for rebroadcasting television programs, which are placed into an orbit at an altitude of about 36,000 km, which ensures a constant position of the satellite relative to the Earth’s surface (the period of revolution of the Rainbow satellite is equal to the period of rotation of the Earth around its axis) .

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Scheme of television broadcasting using the Ekran satellite On October 26, 1976, the Soviet Union launched a new television broadcasting satellite, Ekran, with on-board relay equipment providing the transmission of color or black-and-white programs of Central Television to a network of public receiving devices located in populated areas. points of Siberia and the Far North

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A man whose name was kept secret during his lifetime... Since 1959, he worked as a leading engineer in the closed city of Krasnoyarsk-26. He was a direct participant in the production and launch of the very first long-range military ballistic missiles, then he worked on the production of multi-series space satellites of the Earth series “Cosmos”, communication and television satellites such as “Molniya”, “Rainbow” and “Ekran”.

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A man whose name was kept secret during his lifetime... He was the chief specialist and then the chief expert on new communications satellites in his production association. I visited Baikonur many times - to test my communications satellites, met with many scientists, and was personally acquainted with Sergei Pavlovich Korolev and Academician Andrei Dmitrievich Sakharov.

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A man whose name was kept secret during his lifetime... Unfortunately, we, fellow countrymen, learned about this and his other merits only after his death. In 1992, fulfilling his last will, his nephew, Vyacheslav Vasilyevich Atlasov, friends and colleagues brought the body of E.I. Aprosimov to his homeland in the village of Kyuptsy.

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A man whose name was kept secret during his lifetime... Aprosimov Efrem Ilyich (1922 - 1992) Efrem Ilyich was born in January 1922 in the Tumul area of the Kyup nasleg of the Ust-Maisky district in a large family, the sixteenth and last child.

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Efrem Ilyich Aprosimov After graduating from the Kyup primary and Ust-May seven-year schools, he began working as a teacher at the Kyup primary school, then as the head of this school, and as a military commander at the Ezhan school. In front of you are unique documents-copies.

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Aprosimov Efrem Ilyich Certificate of completion of the Ust-May school and a workbook in physics of the 6th grade

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Aprosimov Efrem Ilyich Order No. 1 of the department of public education of the Ust-Maysky district on the appointment of Aprosimov as a primary school teacher

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Aprosimov Efrem Ilyich In 1943, he voluntarily went to war. He returned from the war with two orders: the Order of Glory and the Order of the Patriotic War, three medals: “For Military Merit,” “For Victory over Germany,” and “For Victory over Japan.” Certificate of gratitude from the Commander-in-Chief of the Soviet Union Generalissimo I.V. Stalin. No. 372 dated August 23, 1945

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Aprosimov Efrem Ilyich After the war, he graduated with honors from the workers' faculty and the Pyatigorsk Pedagogical Institute (department of physics and mathematics) and taught at the Ust-May school.

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Aprosimov Efrem Ilyich In 1952 he moved to the Stavropol Territory and became a student at the Taganrog Radio Engineering Institute. Became the first graduate - a specialist in space radio communications and telemechanics.

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40 slide

Radio communication – transmission and reception of information using radio waves propagating in space without wires.

Radar

Radiotelephone

Types of radio communication

Radiotelegraph

Broadcasting

A television

Popov Alexander Stepanovich, Russian physicist and electrical engineer, inventor of electrical communication without wires (radio communications, radio). In 1882 he graduated from the Faculty of Physics and Mathematics of St. Petersburg University and was left there to prepare for scientific work.

Popov's first scientific research was devoted to the analysis of the most beneficial action of dynamoelectric machines (1883) and induction balances Yuza (1884). After the publication (1888) of G.’s works. Hertz in electrodynamics, Popov began to study electromagnetic phenomena and gave a series of public lectures on the topic “The latest research on the relationship between light and electrical phenomena.” Trying to find a way to effectively demonstrate Hertz's experiments to a large audience, Popov set about constructing a more visual indicator of electromagnetic waves (EMWs) emitted Hertz vibrator .

To produce electromagnetic waves, Heinrich Hertz used a simple device called a Hertz vibrator. This device is an open oscillatory circuit.

Radio receiver circuit
A. S. Popova:
M and N- holders to which the coherer is suspended by means of a light clock spring;
A and B- platinum coherer plates, to which the voltage of the electric battery (P-Q) is constantly supplied through a polarized relay (Relay).

Principle radio communications is is that it was created high frequency electric current , created in the transmitting antenna, causes in the surrounding space rapidly changing electromagnetic field , which distributed by as electromagnetic wave .

Basic principles of radio communication

Receiving circuit

speaker

Before. antenna

Reception. antenna

Basic principles of radio communication. Block - diagram.

Master oscillator (GHF) produces harmonic HF oscillations.

Microphone converts mechanical sound vibrations into electrical vibrations of the same frequency.

Modulator changes (modulates) the frequency or amplitude of HF oscillations with the help of electrical oscillations of low LF frequencies.

High and low frequency amplifiers UHF and ULF enhance the power of high-frequency and low-frequency electrical vibrations.

Transmitting antenna emits modulated electromagnetic waves.

Receiving antenna receives electromagnetic waves. An electromagnetic wave, reaching the receiving antenna, induces in it an alternating current of the same frequency at which the transmitter operates.

Detector selects low-frequency oscillations from modulated high-frequency oscillations.

Speaker converts electromagnetic vibrations into mechanical sound vibrations.

In 1899, P. N. Rybkin and D. S. Troitsky, Popov’s assistants, discovered the coherer detector effect. Based on this effect, Popov built a “telephone dispatch receiver” for auditory reception of radio signals (on headphones) and patented it (Russian privilege No. 6066 of 1901). Receivers of this type were produced in 1899-1904 in Russia and France (Ducretet company) and were widely used for radio communications. At the beginning of 1900, Popov’s devices were used for communication during the work to eliminate the accident of the battleship “General-Admiral Apraksin” off the island of Gogland and during the rescue of fishermen carried away on an ice floe at sea. At the same time, the communication range reached 45 km. In 1901, Popov, in real ship conditions, obtained a communication range of 148-150 km.

When work on the use of radio communications on ships attracted the attention of foreign business circles, Popov received a number of offers to move to work abroad. He resolutely rejected them. Here are his words:
« I am proud that I was born Russian. And if not my contemporaries, then perhaps our descendants will understand how great my devotion to our homeland is and how happy I am that a new means of communication has been discovered not abroad, but in Russia ».

Radar - detection of objects and determination of their coordinates using the reflection of radio waves.

Radars are used to determine the distance and detect aircraft, ships, cloud accumulations, planetary locations, and in space research. Using radar, the speed of the orbital motion of the planets, as well as the speed of their rotation around their axis, is determined.