Radio Engineering Equipment
II
0907
629.123+656.61.052
= Radio Engineering Equipment. II 0907 / . .. . : - , 2009. − 36 .
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充4
4. Lesson 1. Telegraphy Without Wires.5
5. Lesson 2. Radio Direction Finders8
6. Lesson 3. Radio Beacons.10
7. Lesson 4. Radio Compass14
8. Lesson 5. Radar16
9. Lesson 6. Radar Guns 20
10. Lesson 7. Radio Telescope..22
11. Lesson 8. Antennas. 26
12. Lesson 9. Facsimile. 29
13. Lesson 10. Pager..32
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LESSON 1. TELEGRAPHY WITHOUT WIRES
1. Read the new words:
wireless telegraphy ,
to deliver ,,
rate ,
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electric wave ()
Hertzian waves
to project ,
refraction
telephone exchange
telegraphic communication/message
induction ,
mainland ,
by means of
parallel wires
insulated wire
to earth
running stream
to skirt , ,
overhead wire
to dispatch ;
to set in motion ,
inestimable value
shipping , ,
lightship
lighthouse
2. Read the text and translate it:
An invention which promises to be of the greatest practical value in the world of telegraphy has received its first public announcement at the hands of Mr. W. H. Preece, the telegraphic expert of the London post office. During the course of a lecture on "Telegraphy Without Wires," recently delivered in London, Mr. Preece introduced to the audience a young Italian, a Mr. Marconi, who, he said, had recently come to him with a system of telegraphy without wires "which depended, not on electro-magnetic, but on electro-static effects, that is to say, on electric waves of a much higher rate of vibration, not less than 250,000,000 a second; that is, Hertzian waves." These vibrations were projected through space in straight lines and, like light, were capable of reflection and refraction, and, indeed, they exhibited all the phenomena which characterized light.
Telegraphing without wires was, of course, no new idea. Mr. Preece stated that in 1884 operators in the telephone exchange, London, were able from sounds heard to read messages that were in transit from London to Bradford by the telegraph wires. The post office wires were underground and the telephone wires above ground, and careful experiment showed that this fact accounted for the telegraphic messages to Bradford being read by the telephone company. In 1893 telegrams were transmitted a distance of three miles across the Bristol Channel by induction, and during a break in the cable connecting the island of Mull with the mainland communication was established by means of parallel wires as follows: On the mainland an insulated wire was laid along the ground, earthed in a running stream at one end, the other end being in the sea. Skirting the coast of the island was an overhead wire suited to the purpose. In the course of four days one hundred and fifty-six messages were dispatched.
The invention of young Marconi solved the problem on entirely different principles. The post office officials had used it successfully on the roof of the general post office, and then made a successful test on Salisbury Plain at a distance of three-quarters of a mile. The great difference between the Marconi and the inductive methods of wireless telegraphy was that the former did away entirely with the wires at each end. Vibrations were set up by one apparatus and received by the other.
The apparatus consisted of two plain boxes which were placed at opposite ends of the hall. The current was set in motion in one box, and immediately a bell was rung in the other.
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If the experiments were successful, it would be of inestimable value to shipping, for it would provide another easy way of communicating with lightships and lighthouses, it would make navigation infinitely easier and safer than it now was.
3. Answer the following questions:
Who was Mr. Marconi?
Did a system of telegraphy without wires depend on electro-magnetic effects?
What waves do we call the Hertzian waves?
Was the telegraphing without wires a new idea?
How were the telegrams transmitted in 1893?
What problem did the invention of young Marconi solve?
How did the Marconis apparatus work?
4. Give the equivalents, using the text:
a) , , , , , , , , , , , , .
b) be of the greatest practical value, the telegraphic expert, public announcement, a system of telegraphy without wires, to depend on electro-static effects, in straight lines, to be capable of reflection and refraction, to exhibit all the phenomena, operators in the telephone exchange, to be transmitted a distance of three miles, to be established by means of parallel wires, the current was set in motion, inestimable value to shipping.
1) Select the correct form in parentheses in the following sentences:
a. This invention promised to be one of the (greater, greatest) discoveries in the world of telegraphy.
b. A system of wireless telegraphy depended on electric waves of a much (highest, higher) rate of vibration.
c. The experiment was (more careful, carefuller) than the previous one.
d. The invention of young Marconi showed (much successful, more successful) results.
e. Telegraphing without wires will make navigation infinitely (easier, easiest) and (safer, safest) than it is now.
2) Correct the following statements if you find them wrong:
Mr. W.H. Preece made the first public announcement of his invention which promised to be of the greatest practical value in the world of telegraphy.
A system of telegraphy without wires depended not only on electro-magnetic, but on electro-static effects.
Hertzian waves exhibited all the phenomena which characterized light.
The telephone wires were above ground, the post office wires underground.
The inductive methods of wireless telegraphy did away entirely with the wires at each end.
3) Choose the correct form of the verb in parentheses in the following sentences:
The study of the electric waves (were/was) of the greatest practical value in the world of telegraphy.
The quality of the boxes and bells (is/are) not very good.
If the duties of the telegraphic experts (isnt/arent) reduced; there will not be enough time to finish the project.
Mr.Preece, accompanied by Mr. Marconi (is/are) arriving tonight.
The use of the inductive methods (have/has) increased in recent years.
6) Hertzian waves as well as light (were/was) capable of reflection and refraction.
7) The rates of vibration (vary/varies) from subject to subject.
8. Translate from Russian into English:
1. , .
2. , .
3. , .
4. .
5. , .
Sum up what the text said about the wireless telegraphy.
LESSON 2. RADIO DIRECTION FINDERS
3. Read the new words:
radio direction finder
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the Allies ; (, )
to track , ;
U-boat
to sense ; , ;
radiogoniometer
loop aerial
to wire []
field coil ;
search coil
to rotate ()
to resonate
aerial circuit , ()
to diminish (), ()
magnetic flux ,
automatic direction finder
solenoid
to spin (), ()
peak , ,
trough ,
compass rose
string ,
VOR (very-high-frequency omnidirectional range) KB-
GPS (Global Positioning System)
user-friendly ,
4. Read the text and translate it:
Due to radio's ability to travel very long distances "over the horizon", it makes a particularly good navigation system for ships and aircraft that might be flying at long distances from land.
High frequency radio direction finders (known as HF/DF or huff-duff) were employed by the Allies to track German U-boats during WWII.
The earliest radio direction finder was the radiogoniometer invented by Bellini and Tosi in 1907. In the BT radiogoniometer, two loop aerials (one positioned North-South and the other East-West, or Fore-Aft and Port-Starboard on a boat) were each wired to a field coil (which were mounted at right angles to each other). A rotating search coil (which was attached to the receiver) was then placed between the two field coils. A loop aerial resonates best when the radio wave approaches it from the side, and so the degree to which an electric current is induced in the aerial circuit diminishes as the waves angle of approach increases. Each field coil will then produce a magnetic field proportional to the current induced in the aerial. The search coil receives a proportion of the magnetic flux from each field coil depending on the direction it faces. The search coil achieves maximum magnetic flux when it favors the coil with the greater magnetic field, and it is at this position that the search coil points in the direction of the radio transmission.
In more recent times the task of finding the signal has been automated in the automatic direction finder, or ADF. In this system the antenna consists of a small cylinder of wire, a solenoid that is highly directional, which is spun by a motor. The electronics listen either for the repeated "peak" in the signal, or just as commonly, the "trough" when the signal drops to zero when the antenna is at right angles to the signal. A small lamp attached to a disk is timed to spin at the same speed as the antenna, so when the peak or trough is detected the lamp flashes briefly. To the human eye it appears to be a single spot of light on top of a compass rose.
RDF was once the primary form of aircraft navigation, and strings of beacons were used to form "airways" from airport to airport. In the 1950s these systems were generally being replaced by the VHF omni range (VOR) system, in which the angle to the beacon can be measured from the signal itself, with no moving parts.
Today all such systems are being generally removed in favour of the much more accurate and user-friendly GPS system. However the low cost of ADF systems today has meant something of a comeback, whereas the expensive VOR systems will likely all be switched off before 2010.
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5. Answer the following questions:
4. What are the radio direction finders used for?
5. Who was the inventor of the earliest radio direction finder?
6. What elements did the radiogoniometer consist of?
7. How did the radiogoniometer work?
8. What is ADF?
9. Why did GPS system remove ADF and VOR systems?
4. Give the equivalents, using the text:
a) , , , , , , , , , , , , , , , , , .
b) to travel very long distances, navigation system for ships and aircraft, two loop aerials, to be wired to a field coil, rotating search coil, electric current is induced, to produce a magnetic field, a proportion of the magnetic flux, direction of the radio transmission, signal drops to zero, to spin at the same speed as the antenna, the lamp flashes briefly, a single spot of light, more accurate and user-friendly GPS system.
1) Put the questions to the underlined words:
5. High frequency radio direction finders are known as HF/DF or huff-duff.
6. The earliest radio direction finder was the radiogoniometer.
7. Two loop aerials were each wired to a field coil.
8. The degree to which an electric current is induced in the aerial circuit diminishes.
9. The search coi l receives a proportion of the magnetic flux from each field coil.
10. In the ADF system the antenna consists of a small cylinder of wire.
2) Translate from English into Russian, paying special attention to the Complex Subject Construction:
5. Radio direction finders are assumed to be good navigation devices for ships and aircraft.
6. RDF was known as a primary form of aircraft navigation.
7. RDF system is likely to be widely used in the 1930s and 1940s.
8. In WWII, ship-based huff-duff was found to be implemented with a number of changes to the original BT radiogoniometer design.
9. True direction was found either by incorporating an antenna into the huff-duff unit.
10. Wires from each dipole seem to be looped together into a single field coil.
11. For a long time the general concept of the original radiogoniometer was thought to be unchangeable.
12. The above mentioned text is certain to be very interesting.
7. Translate from Russian into English:
, ,
, .
.
, .
.
1907 .
.
GPS , .
8.Sum up the information about radio direction finders.
LESSON 3. RADIO BEACONS
1) Read the new words:
radio beacon
aid
overcast , ,
to distract
urban sprawl
handicap ,
to hasten (-. . .)
to space
Morse-code signal
beam ,
to merge (), ()
steady ,
drift , |
to stray ,
ILS (instrument landing system)
compass locator
to orient , ,
glideslope , ()
to guide , ,
homing beacon
homing aids
VFR (visual flight rules)
voice circuit
preflight
homing signal
obsolete
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backup ,
artefact () , , ,
2) Read the text and translate it:
While early flashing beacons were economical and a great aid for night-time navigation in clear weather, they were of no value in overcast conditions, or during the day when they werent even turned on. And they were sometimes difficult to locate in the distracting light of urban sprawl. These handicaps hastened the development of the LF (low frequency) navigation system.
Radio beacons in the 190 to 535 kHz radio band had formed the earliest LF navigation system. These powerful, 1500-watt beacons were spaced about 200 miles apart and defined electronic airways.
The beacons transmitted two Morse-code signals: the letter "A," , and its opposite, the letter "N," . When the aircraft was centered on the airway, or electrical beam, these two opposite Morse-code signals merged into a steady tone.
If the aircraft drifted off course to one side, the Morse code for the letter "A" could be faintly heard. The greater the drift, the stronger the "A" Morse code signal. Straying to the opposite side produced the "N" Morse code signal.
The low frequency beacon system developed the early 1950's, still in use today, consists of four main types of beacons, listed below in the order of lowest to highest transmitter power:
A) ILS APPROACH BEACONS
Sometimes called compass locators, these beacons are generally 25 watts or less.
The beacons help the pilot find and orient himself to the ILS course, so the localizer and glideslope transmissions can then take over and guide the pilot into the airport. They can be distinguished from other beacons on the air because they have 2 letter Morse code identifiers.
B) AIRPORT HOMING BEACONS
These beacons are used at airports that do not have a ILS system to serve as a general homing aid to that airport. As such they are primarily a benefit to small plane pilots, and can only be used under VFR conditions. They are most commonly also 25 watts, but some airport beacons can be up to 100 watts.
C) CROSS COUNTRY/WEATHER BROADCAST BEACONS
These beacons were put about 200 miles apart, and had a transmitter power of up to 400 watts typically. They had voice circuits to broadcast weather, usually with continuous tapes. Being on low frequencies, they could be heard on the ground, for preflight use.
D) LONG RANGE WATER CROSSING BEACONS
Most powerful and rare type of beacon. They are generally of 2000 watts and were established mainly on coastlines and islands to provide a homing signal for planes flying in from a transoceanic crossing or crossing a body of water for a few hundred miles.
All forms of low frequency homing beacons are technically obsolete in relation to VOR's and now GPS, and are largely no longer used by most pilots.
In any case, because low frequency beacons are so cheap and easy to operate as a backup, they may never completely disappear. Perhaps, similar to lighthouses, which have also been obsoleted by GPS, we should preserve a few radiobeacons for the future as historical artifacts, coming as they do from the earliest days of radio.
3) Give the equivalents, using the text:
1) , , , , 200 , , , , , , , , , , .
2) flashing beacon, great aid for night-time navigation, to be of no value, to be turned on/off, to locate in the distracting light, to define electronic airways, merged into a steady tone, to drift off course, straying to the opposite side, compass locators, to be distinguished from, to serve as a general homing aid, continuous tapes, in relation to, to be no longer used by, to preserve radio beacons for the future.
1) Answer the following questions:
a. What are the advantages and disadvantages of the early flashing beacons?
b. What beacons does the earliest LF navigation system include?
c. How were the Morse-code signals transmitted?
d. When was the low frequency beacon system developed?
e. What is the main function of the ILS approach beacon?
f. What kind of beacons can serve as a general homing aid to the airport, which doesnt have a ILS system?
g. Long Rang Water Crossing Beacons were established mainly on coastlines and islands to broadcast weather, werent they?
h. Will low frequency beacons disappear soon?
2) Match each word in the left-hand column with the best meaning in the right-hand column.
1. The beacons were economical and a) Long Range Water Crossing
of great value in clear weather in Beacons
night-time.
2. The beacons had the lowest b) Flashing Beacons
transmitter power they
had 2 letter Morse code
identifiers.
3. The beacons helped small plane c) ILS Approach Beacons
pilots and often had T type
antennas.
4. The most interesting class of beacons d) Cross Country/Weather
being on low frequencies, people were Broadcast Beacons
able to tune the beacon band on their
portable radios just to get the weather.
5. These powerful beacons could e) Airport Homing Beacons
provide a homing signal for
planes flying too far for a VHF
range.
3) Translate from Russian into English:
a. , .
2) 190 535
.
3) ILS 25 .
4) ,
5)
,
.
4) Sum up what the text said about radio beacons.
LESSON 4. RADIO COMPASS
1. Read the new words:
radio compass
glimme r ,
to determine
bearing ; , ,
fixed loop antenna
needle ()
heading , ,
deflection ()
to mount ,
cancel out , ,
null
amplifier
homing device ;
rotatable
to eliminate ,
cumbersome
fuselage , ,
cockpit ,
triangulation
dial , ,
flight chart
Read the text and translate it:
The Radio Compass was the first glimmer of hope in determining bearings to a radio station. It added a fixed loop antenna and visual indicator to the receiver system. With this system, as long as the aircraft was headed directly toward a radio station the needle of the indicator remained centered; headings to the right or left of the station resulted in a corresponding deflection of the needle.
A loop antenna was mounted on the back of an aircraft. If the plane of this antenna pointed to a radio beacon, the signal strength was a maximum, while a signal facing the loop induced voltages that cancelled each other out, resulting in a weak or null signal. The loop antenna was connected to an amplifier, which drove an indicator on the cockpit's control panel.
The radio compass was chiefly used as a "homing" device, and bearings of radio stations off the line of flight could be obtained only by turning the aircraft toward the station and noting the magnetic compass heading when the needle was centered.
Replacing the fixed loop antenna with a rotatable loop eliminated this cumbersome maneuver. With the rotatable loop, bearings could now be obtained without turning the airplane itself. The pilot or navigator would rotate the loop, usually mounted on the fuselage below the cockpit, to the position of minimum signal strength, or "null." The bearing to the radio station was then read from a graduated, mechanical dial.
By repeating this procedure with a second beacon an aircraft's position could be determined by triangulation after locating the two stations on the flight chart.
1. Answer the following questions:
What does the radio compass determine?
The radio compass is basically a radio receiver fitted with a loop antenna, isnt it?
Where was a loop antenna mounted?
How could bearings of radio stations off the line of flight be obtained?
What did a rotatable loop dominate?
7. Paraphrase the following sentences, using the following words and word combinations: to head, deflection of the needle, to determine bearings, antenna, dial, fuselage
9. The radio compass helped to find out the direction or angle to a radio station.
10. The aircraft traveled towards a radio station.
3) Headings to the right of left of the station resulted in a corresponding degree to
which the needle on a measuring instrument moved away from zero.
11. The loop aerial itself is very directional.
4) The loop is usually mounted on the main part of a plane, in which people sit or
goods are carried.
5) The bearing to the station was read from a graduated round part that showed you the
measurements.
1) Translate from English into Russian, paying special attention to the Complex Object construction:
(1) Everybody knows the radio compass to be basically a radio receiver fitted with a loop aerial.
(2) We heard the loop aerial be very directional.
(3) We want the research to be continued.
(4) Scientists found the replacing the fixed loop antenna with a rotatable loop to have eliminated the cumbersome maneuver.
(5) Observations show the bearing to the radio station to be read from a dial.
6. Find the equivalents:
, , , , , , , , , , , , .
