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COMMUNICATION AND SOLUTION OF PROBLEM TIME MEASUREMENT
Adzhemov A.S., Khromoy B.P.,
MTUCI, Moscow, Russia, [email protected]
Keywords: time measurement, communication technology, networks.
People are faced with the need measurements in antiquity at an early stage of social development - in practical life: in agriculture, housing construction, of palaces and temples in trade. People had to measure the distance, area, volume and time. Measure the distance, area, volume which were required during the construction stimulated the development of mathematics. Measuring the area gave impetus to the emergence of this science geometry, because it was necessary to determine area of triangles, circles and other more complex shapes. The area of the rectangle is determined by the product of the lengths of the sides. This problem can be solved using arithmetic which facilitated development in the solution of practical problems. An even stronger influence on the development of science had the task of measuring time. The idea of time is perceived by a human is much more difficult than the idea of space. Universal properties of time duration and irre-versibility. The un usual properties of time boosted the development of a whole section of philosophy. The timing issue was discussed in the works of Aristotle (384-322 to AD).
All reference signals frequency and time were aimed at the solution of the problem generation and transmission of time signals, that is to solve problems in other areas of technology. However, the solution of the problem of high-precision measurements time and transmit corresponding signals in the last time had a significant impact on the communication technology. With the transition to digital methods of signal transmission became urgent problem with synchronization in communication networks which also is associated with the time dimension.
Для цитирования:
Аджемов А.С., Хромой Б.П. Связь и решение задачи измерения времени // T-Comm: Телекоммуникации и транспорт. - 2015. - Том 9. -№12. - С. 72-76.
For citation:
Adzhemov A.S., Khromoy B.P. Communication and solution of problem time measurement. T-Comm. 2015. Vol 9. No.12, рр. 72-76.
T-Comm Том 9. #12-2015
The history of time measurement
An even stronger influence on the development of science had the task of measuring time. The idea of time is perceived by a human is much more difficult than the idea of space. Universal properties of time duration and irreversibility. The un usual properties of time boosted the development of a whole section of philosophy. The timing issue was discussed in the works of Aristotle (384-322 to AD).
If philosophical problems of determining the time to go to the task measure the time it detected a huge influence this task on the development fundamental and technical science, especially astronomy. Known 13 ancient observatories. Researchers surprised by an unusually high level astronomical knowledge in ancient times which results in subtle and long-term astronomical observations.
In a further development of practical astronomy was carried out very intensively Were later created the Observatory in Baghdad, Cairo, Maragha (Nasr Eddin), Samarkand (Ulug beg), in Seville, etc. Since the beginning of XVI century in Europe began built observatory in Nuremberg, in Kassel (1561). In the XVI century, the famous astronomer Tycho Brahe all his wealth used in construction and tools his Observatory Uraniborg on the island of Veins in the Strait Eresund. The first government Observatory in Europe - the round tower, was built in 1637-1656 years in Copenhagen.
The Paris Observatory launched in 1671, the Greenwich Observatory is open after Paris in 1675. Next were open Observatory in cities Leiden (1690), Berlin (1711), Bologna (1714), Utrecht (1726), Pisa (1730), Uppsala (1739), Stockholm (1746), Lund (1753), Milan (1765), Oxford (1772), Edinburgh (1776), Dublin (1783). By the end of the XVIII century in Europe there were more than 100 Observatory and by the beginning of XX century they number reached 380.
In Russia, the first astronomical Observatory was built in 1692 year (Kholmogory near Arkhangelsk), the second Observatory appeared in Russia in 1701 year in Moscow at Navigation school. The first official Observatory in Russia, founded by Peter I, simultaneously with the Academy of Sciences in 1725 year.
June 21, 1835 realized bookmark Pulkovo Observatory. The solemn consecration of the finished building was held on August 7, 1839 year. The construction of the Observatory cost expenditure 2100500 RUB.
All information is listed, concerning ancient and modern observatories indicates that an extremely high interest shown to astronomical research in all historical times. The question arises, why? Astronomical research had always greater importance to solve the two problems in cartography and navigation.
The task of navigation in ancient times was associated with sailing. For rational and safe shipping, you must have accurate map and the possibility of any other way to measure coordinates ship - to know the latitude and longitude.
Measurement of latitude did not cause difficulties because of this, it was enough using goniometric device to measure the maximum angle position of the sun. The principle of determining longitude was known to Hipparchus: the difference of the longitudes of the two points corresponds to the difference of local times while observing the moment any single event in those place.
Thus the main problems of the sea navigation were associated with time measurement. The problem was urgent and most importantly she had the economic basis since the death of the ship has send to large losses. Therefore, the rulers of some countries offered substantial prize for a solution to this problem.
In 1567year the Spanish king Philip II appointed reward to anyone who can find a simple way to determine a simple way to determine longitude at sea. In 1598 Philip III repeated the promise of reward. Large sums were offered the Netherlands, Portugal and Venice.
Ehis task was interested Huygens and he in 1655year began designing watches. Most of all it is evident from the letters of the scientist he was interested in sea watch that would be able to keep time for many months in any climatic conditions and in all the movements of the ship. The first idea of a pendulum clock expressed Galileo. However, to bring the idea to a real design managed only the Huygens in 1658 year.
In the invention of the clock spring created force resulting in the movement system wheels hours and the pendulum has provided the rate regularity. Were used his achievements on the theory pendulum. In the invention of the clock spring was created power, driving system wheels hours and the pendulum has provided uniformity (равномерность) of their progress ходаМ^^ hours Huygens achieved sought accurate isochronism oscillations of the pendulum and creation of a support anchor escapement whereby the pendulum receives periodic jerks who don't give him to stop because of friction and air resistance.
Under the isochronous understand independence the period of oscillations on the amplitude oscillations of the pendulum. This was important because the instability amplitude occurring during gradual the reduction steps clock work spring caused a temporary deviation.
In 1662 1677 gg "keepers time" Huygens tested on sea. Watch on ships attached to the post and closed a special case. Later, to reduce the effect of pitching Huygens proposed to hang the clock in a cardan ring. In 1668 year watch Huygens stand two storm and naval battle, allowed to determine the difference of longitude between Toulon and Crete error in 100 kilometers. It was undeniable progress for that level of navigation. However, positive results were often followed by failure.
Huygens analyzed the results of all tests came to the conclusion that the pendulum despite all the measures taken, on the ship works randomly and not very reliable. Even a small change in the length of the pendulum for example due to the increase or decrease temperature significantly affect the accuracy of the clock. Therefore, in 1674 year he refused it and proposed as a regulator of a course to use the balancer - the flywheel engaged by means of a spring oscillatory motion about the equilibrium position. This was a significant step forward. But it took another 100 years until it was possible to make marine chronometer meet the requirements of mariners.
However, Huygens, we must not only device of the pendulum to the clock but also the development of the foundations of his theory in particular the definition formula his movements. Published in 1673 year the book by the scientist "Pendulum clock" is the most prominent works on mechanics written in the XVII century. Not by chance it was put in one number the famous "Beginnings" Isaac Newton. This book Christiaan Huygens played a major role in the development of radio engineering, which is built on the theory of vibrations.
Despite the success in improving in improving pendulum clock the navigation problem remained unsolved. The late XVII and the beginning of XVIII century was marked by a number of large Maritime disasters. In 1691year off the coast of England ran aground several warships taken near Plymouth Cape Doman for Cape Berry- Hid. In 1694 year due to errors in the calculation of your location in the Strait of Gibraltar ran aground squadron Wheeler. The most tragic was the loss of several ships of the British squadron Admiral Cloudesley Shovel claimed nearly 2000 lives and the Admiral.
Because of the death of a large number of people determining longitude was the subject of frequent debates in the English Parliament. His solution was to set up a special Commission, which included such prominent scientists as I. Newton, E. Halley, J. Flamsteed. June 17, 1714 year presented by the Commission bill was approved by the Parliament and on 1 August1714 signed by the Queen England Anna. Aaccording to this law, the author or authors proposed the project to determine the longitude with accuracy at least 1 gradus or 60 marine mile was promised a major prize of 10 thousand pounds; 15 thousand pounds will be provided if will be provided accuracy at least 40 mile, and 20 thousand pounds - 30 mile (20 thousand pounds XVII centery equivalent to almost half a million current). In this case the law of longitude was made significant reservation, the proposed method should be "tested and evaluated from the point of view of its practicality and use fulness of the sea".
The example of England was followed by France. In 1716 the Regent Philippe Duke of Orleans for the determination of longitude was established prize awarded by the French Academy of Sciences. The law and assigned prizes was a good incentive to activate work the solution to the problem of safe navigation. However, none of the incoming the Board offers up to 1737year fully approved no.
Award in accordance with the law on longitude in total 22500 pounds was awarded only in the mid the seventies XVIII century eighty-year-old mechanic John Harrison or as it is called John Longitude, for the creation of high-precision hours of chronometers (from the Greek "Chronos" - time and the "metros" - measurement), which allowed finally to solve the problem of the ages.
John Harrison is the son of a village carpenter of Oakfield in Yorkshire in his youth he was fond of hours and has achieved good results - designs created hours differed accurate and stable speed. In 1730 year by bang in the London he first learned of assigned the Parliament of the prize and the fact that one of the ways solution longitudinal of the problem lies in establishing an accurate " time Keeper".
The task seemed capable and he began to work. Harrison started with the solutions to the issues that arose before Huygens: it was necessary to minimize the dependence the clock from the change temperature, humidity, pitching and course of the ship.
Harrison finished work on the first chronometer in 1735 and submitted it to the the Board of longitude. The design was very unusual. The pendulum has been replaced by
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two large balance wheel which rocked in opposite directions, so that the effect of the movement of the ship on one the balancer was compensated by other. Themselves balancers were composite made of different materials for temperature compensation. To specify a time were provided by four dial - for seconds, minutes, hours and days. The chronometer was very cumbersome and weighed over 30 kilogram although many of the details were made from wood.
After the testing chronometer, which showed good results Harrison continued work to for improvement. In 1739 he was made a second sample chronometer. It work the did not satisfy the Harrison, but also prompted a number of new ideas and he started making the third option chronometer. It took 19 years.
In 1761 he began testing which showed high quality chronometer. While preparations were made for the tests Harrison has prepared the fourth option chronometer. The tests showed good results. For 81 days swimming chronometer accumulated error of only 5 seconds. On the way to the England error coordinate upon arrival in Portsmouth was only 16 miles.
However, the final decision on the adoption of the chronometer and the remuneration in accordance with the bill from 1714 year , was made only after Harrison opened the secrets of its manufacture and watchmaker Larkum Kendall made it up. This model of Kendall and three others made J. Arnold on the recommendation of the Board, he took n his second voyage of captain J. Cook. According to the testimony of J. Cook during a three-year voyage chronometer manufactured by Candell proved perfectly
Watches made by Harrison was the prototype and so it was very expensive. These watch served as a model for young artists, hard chronometer cheap enough to be by means of each Navigator. In those days the master John Arnold enjoyed great respect. Together with his son Arnold made chronometer such the quality of what they are in for 50 years widely used on ships around the world. The problem of longitude was thus final-y solved.
Advantages of chronometers or as they are also called "longitudinal hours" were quickly appreciated by seafarers, but they were introduced on ships slowly since only a highly skilled mechanics can make, and then only in small quantities can produce. And they cost very expensive. However, all large swimming the second half of the XVIII century was done already with chronometers. They were used by J. Cook, J. lapeyrouse, D. Anticaste.
Mass production of chronometers for navigation was developed in the countries in Western Europe only in the late XVIII to the early XIX century.In Russia had their outstanding wizard to create high-precision clock. Among them, the mechanic of the Russian Academy of Sciences I.P Kulibin (1735-1818), T.I.Voloskov (1729-1806), LFSobakin (1746-1818), etc.
Sobakin created astronomical clock which in its complexly had no equal. But it was of course the wall clock large. Marine chronometers Russian masters at that time not produced and purchased from foreign firms mostly in English. Six of these chronometers were installed on Board the sloops "Nadezhda" and "Neva", commited in 1803-1806 years circumnavigation under the command I.F Krusenstern and J.F Lisyansky. Using chronometers were determined longitude F F Bellingshausen and M. P Lazarev during an expedition to Antarctica in 1820 year on the sloops 'Vostok" and "Mirny". So in his diary M P Lazarev noted: "Were in Tahiti for check their chronometers, which turned out to be true, and therefore to conclude can that opening our presents on maps with high precision".
Procured from foreign companies chronometers were carefully checked in the Kronstadt naval Observatory organized in 1856 year. and then sent them to the ships. Here also conducted research on the consistency of their progress sensitivity to changes n temperature, humidity and etc.
In 1849 year at the exhibition of Russian manufactured goods as the exhibit has already been submitted sea chronometer made by the Russian master A.F Rogin. From 1865 year chronometers began to produce located in Petersburg workshop August Erickson. The product of this workshop received high evaluation in a number of industrial exhibitions and among sailors. They almost drove chronometers bought abroad. This workshop served the needs of the Navy to 1902 year, when did the second workshop of Charles Erickson - homonym August. Dependence from import with the opening of this masterful was minimized.
Close history invention and perfection marine chronometer should note what in base its construction of a solution problem measuring longitude in sea condition, be put not pendulum, but beam mechanism where in instead pendulum apply balance-wheel rippling which realize under the influence spring and anchord. That construction on not
influence outside mechanical action, began be used in widely distributed wrist-watch.
In that way working, an action marine chronometer at the same time of a task very relevant, everyday problem and during many years these clock make numerous firm in millionth quantity be basic measuring device time way of life. As to chronometer Harrison that out of last 250 years its construction small modify (modify technology manufacture and use material).
Electrical clock
In 1880 year N.Tesla commencement of works on research alternating electricity current. Applied of matter measuring time should devise him electromechanical generator and base on its principle electrical clock. N.Tesla beginning working on high-frequency put beginning radio engineering.
Ought to note, what working on produce mechanical clock and chronometer, provide its influence on development radio engineering, since theory in mechanical devce be applicable of electrical oscillation contour. As regards radio engineering those it influence on evolution clock and chronometer as result of investigation property quartz and creation its basis high- stable quartz generator.
Piezoelectric effect be first open brothers Жаком и Пьером Кюри in 1880 year. First stable on frequency quartz resonator be create in 1920-1930 years. Starting with 1926 year quartz resonators on wireless station use in quality setting carrier frequency element. In that time sharply encrease quantity company beginning let out quartz resonators; only to 1939 years in USA be manufacture more than 100 000 piece. The very popular kind resonator become resonators applayin clock scheme. Resonance frequency clock resonator 32768 hz shared on 15 divide binary counter let interval time 1 second.
First quartz chronometer be maked on valve scheme. Started with 60 ears last century row country (Switzerland, France, USA) fulfill work on create small quartz chronometer, instead of quartz clock make on valve scheme. Dimension and weight quartz clock manage such minimal size, what they become implement function had-held device.Particular significance have progress in development technique microminiaturization radio equipment transistorized technics particular area transistorized apparatus on tunnel diode.
Stepping motor in watch technics replace in electromechanical and electronic -mechanical device working anchoring and ratchet device for transmission impulse on pointer clock or on indicated arrangement. These function begin realize step-type motor. In that case execution unit not have kinematic connection with quartz oscillator and therefore the last not spend kinetic energy for driving executive mechanism. Rippling oscillator come more free and motion clock much exact and stable. Rotation exit roller in that electric motor have discrete step-type character.
Electronics quartz-crystal clock consist from two part. One part generator produce electrical rippling, which stabilize quartz crystal on its resonance frequency. In that way we have generator electrical rippling, in which connection clock. Mechanical arrangement not be able function with such speed. Therefore another subcircuit electronic scheme call divisor, transform these rippling in impulse frequency 1 hertz. These impulse feed on winding step-type electric motor.
Motor consist of stator, stationary assign to him spool with winding and rotor -permanent magnet plant on axis. By passing over spool electrical impulse form magnetic field, and this field turn rotor. Rotor over system pinion rotate pointers.
Starting with 60 year past century small size quartz chronometer manufacture in different country, radio engineering firms and just as traditional clock firm productive mechanical chronometers. Basic progress with introduction quartz chronometers: mistake in special project chronometer not exceed 0,3 second/month. So quartz chronometer give revolution in area navigation, since their accuracy on order higher accuracy their mechanicals predecessor by substantially smaller cost. At present time much firm make arm quartz clock.
All that become possible because of development radio engineerin, for of these be elemental base use in quartz watch.
Atomic clock
Timing mark exact time baze in rotation earth serve basic unit practically in always system unit that time for the time present problem determination unit time with relative mistake not badly 10-10. Because of reason XII General conference on measure and weight commit Internation committee on measure and weight determine molecular or atomic frequency which proper with 1967year begin determination unit time in SI. That
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represent transfer from reproduce unit time from to reproduction frequencies periodic process which stable in time periodical process, since size reverse frequency - period have dimension time.
Since 1967 year, the International system of units (SI) defines one second as
9 192 631 770 periods of the electromagnetic radiation occurs during the transition between the two hyperfine levels of the ground state of the atom of cesium - 133. According to this definition, the atom of cesium - 133 is standard for measurements of time and frequency. The accuracy of a second determines the accuracy of the determination of other basic units such as for example Volt or metre the basic unit containing the second in its definition.
Principle of operation nuclear clock is the formation with help quartz resonator sinusoidal oscillations with a frequency close to 9,1926 GHz. These oscillations are served in a vacuum chamber. In the vacuum chamber of the heater is served evaporated metal cesium. Using the frequency of the phase comparator compares the frequency of the oscillator and the oscillation the cesium atoms. When the difference in phase and frequency fluctuations electrical circuity feedback adjusts the frequency of the crystal oscillator to the desired value, thereby increasing the accuracy of the frequency of the generated signal and its stability.
Based on the above principles for the formation of highly stable sinusoidal signal built State primary standard time and frequency of the RF He is the all-Russian scientific research Institute Physics- technique and Radiotechnical Measurements (VNIIFTRI). State primary standard provides reproduce unit time (and frequency) with an average standard deviation of the measurements does not exceed (3? 5) ■ 10-15 over time intervals of1 to 3 months.
Achieved at the present time, high accuracy calibrate the time needed primarily for cientific and special purpose (space navigation, radio navigation, communication, etc). For marine astronavigation requirements are significantly lower. So for astronavigation measurement world time enough know with an accuracy of tenths to hundredths of a second. For daily activities readings marine watches should not differ from the exact time more than 0,25 minutes.
Summing up, we can conclude that arose in connection marine navigation the problem of accurate measurement time now solved. It should be noted when implementing atomic time standard used experience generation and frequency adjustment accumulated in communications technology
Transmission of the exact time signals
For several centuries there was the problem of transmitting information about the current time from the standard to the consumer. There have been many attempts to solve this problem. Since before the invention of the atomic time standard, the timing for measuring longitude was carried out based on the motion of the earth relative to some starting point, arose the necessity of a choice of Meridian common to all countries.
Now it is well known that longitude is measured from Prime Meridian passes through the Observatory of the town of Greenwich near London. But it wasn't always. The need to restore order in this matter escalated in the era the great geographical discoveries when the geographic maps had to put new lands and to clarify their geographical coordinates. The Royal Observatory was built on a high hill on the site of the old castle in Greenwich start working b 1676 year. Greenwich Observatory have acquired fame and mariners when determining longitude increasingly began to focus on the Meridian of Greenwich the moreover, many used by sailors cards were British origin. To 1871 year for twelve countries on marine charts counted longitude from the Meridian of Greenwich.
In October 1884 year in Washington took place the international Meridian conference "to discuss and if possible for fixation Meridian suitable for use as zero longitude and the lap time around the globe". When discussing the adopted requirements that Meridian must pass through one of the most prominent observatories able to conduct the most accurate observation and when this should not be necessary in a large alteration of the already published maps and manuals.
Most of these requirements were satisfied Meridian of Greenwich more precisely, the Meridian passing through the axis from the Greenwich Observatory telescopes. The international Meridian conference of1884 years, along with the resolution on the zero Meridian took decided to use Greenwich mean time as the world. It was recommended that all almanacs and marine yearbooks issue with the calculation local time Greenwich (GMT).
In order to accurately determine longitude the chronometer should be set by Greenwich time and process must be constantly monitored. At the first stage of this task is
solved or astronomical observations or by comparison with a reference clock showing Greenwich time at the point of departure ship.
For comparison chronometer with the reference "guardians of the world-time" used portable clock as the chronometer is not recommended to once again move in order not to subject him shaking and impact of environmental changes. To set the time portable clock at the dawn of the emergence of chronometers used signals served with the coast specifically for ships in port. As a signal used turn off lights, lowering the flag, shot gun, bells etc.
With the invention of the electric connection, the situation has changed significantly. An electrical pulse is transmitted from reference clock using Telegraph could be actuated in any position of the signal device, gun, bell and etc., located at the greatest distance from the Observatory. In the second half of the nineteenth century alarm devices the exact time driven by Telegraph, have been installed in many major seaports in Europe.
In 1862 year between the Pulkovo Observatory and St. Petersburg was laid Telegraph which began to transmit the time signal. These signals are decided by a shot from a cannon with the territory Admiralty to tell Petersburg noon. In 1905 year, the commander of the sea port of St. Petersburg said the signal shots allow to check the ship's chronometers only accurate to 1,5 seconds which is not enough to navigation purposes. Since then, the signals are fed only for civilian purposes.
In 1866, the largest ship in the world at that time "Great Eastern" was engaged in the laying of the transatlantic Telegraph cable. In the performance this work by just laid the cable on the great Eastern twice a day received Telegraph signal time from Greenwich for the first time in the world allowed without visual observation to deteimine with high precision longitude location of a ship at open sea. But this was an exceptional case since all other vessels not pulled by the cable.
Basic method to improve the accuracy of observations and guarantees from trouble in case of loss of time due to stopping the clock sailors carried with him several chronometers and used the average value of their testimony. The same method increased the accuracy determine longitude various geographic locations. So in 1823 year when determining the difference of longitude between the Dover and Portsmouth sea transported 30 chronometers. When shooting coordinat the Baltic sea in 1833 year expedition Russian geographer F F Schubert used 56 chronometers, and when determining coor-dinaty Pulkovo the Observatory used already 81 chronometer.
The invention of radio radically changed the entire service time in that case and in ships. The first opportunity to transmit signals time on the radio for the needs navigation was used by the Americans. In 1904 these signals to pass radio service in the U.S. Navy from the state of Navesink. In January 1905 year, the regular transmission of the midday time signals the beginning of the radio Washington and in 1907 the radio Norddeich radio Germany. In 1908 year Bureau longitude France decided to send radio signals time with the Eiffel tower. Regular transmission started may 23, 1910 year at midnight. Signal pendulum the Paris Observatory when his swing closed contact the circuit and the cable was powered relays radiating radio installed at the Eiffel tower. Rhythmic signals from the radio station allowed to detect errors reading chronometer with accurate to 0,01 seconds. Since 1912 year, the signals start time to pass Greenwich Observatory
Storage time has been greatly simplified. Sailors could now reconcile thdr chronometers without going into port. Moreover, there was no need in creating extremely accurate ship chronometer capable of storing Greenwich mean time is long and without checks. Every year the number of radio stations transmitting the time signal grew. Each has established its time transmission of signals and their code. There was a need to coordinate this work and in October 1912 year on the initiative Bureau longitude France gathered in Paris conference 16 countries Europe and America on the issue the question radiotelegraph transmission time. In working conference participated and three delegates from Russia.
The conference adopted from 1 July 1913 unified the system time "Onogo" for radio stations all countries and recommended that this schedule work radio stations so they are not interfere with each other. It was envisaged the schedule and for those radio stations, that may appear in future. This came from the fact that at least one signal time per day can be obtained everywhere on the earth except the polar regions. Radio not only allowed to send the broadcast signal time reference clock specific observatories but opened the possibility "merge" time, generated by them, and therefore to create a unified international system generate accurate time, allowing to eliminate the discrepancy time different observatories.
In 1919, at a conference in Brussels was created by the international astronomical Union. At the Congress of the Union was established permanent international Bureau
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time whose task was to coordinate and generalization working all services time world.
In Russia regular radio transmission time began with may 1913 year. Already in 1914 year, an attempt was made to clarify using radio signals time the longitude of the Pulkovo Observatory. In 1920 year astronomical Observatory in Pulkovo has started regular transmission time signal. The signals were transmitted daily via Petrograd radio station "New Holland".Since 1921 year, the signals were transmitted to and through Moscow October radio station on the Khodynka. In 1948 year, in our country was established the interdepartmental Commission of the unified service time under the State Committee standards of the Soviet of Ministers of the main purposes of which were the issues related to the transmission of signals the exact time and coordination work in this area various stakeholder agencies. This is a brief history of the development of time dimension and create a single the transmission system time signal using communications.
Modern navigation systems
The influence of radio communication systems development systems navigation not limited to the amendment of readings chronometer to increase accuracy determine the time. Currently, systems exist navigation in which the radio communication can be applied directly to determine coordinates object. It's good known satellite navigation system.
Satellite navigation system - comprising of ground and space equipment designed to determine the location (geographical coordinates and height) and time and other settings (the speed and direction of movement, and so on) for ground water and air objects. Principle work satellite navigation system based on the distance measurement from antenna on object (coordinate you want to get) before satellites, the position of which is known with great accuracy. Table of provisions of all satellites called almanac should possess any satellite receiver before measurements. Typically, the receiver stores the almanac in memory since the last time off and if he not obsolete - instantly uses it. Each satellite transmits its signal all instantly uses it almanac. Thus knowing the distance to a few satellites system, using a standard geometric constructions on the basis of almanac, you can calculate the object's position in space.
The method of measuring the distance from the satellite to receiver antenna based on the certainty of the speed radiowave propagation, to determine the distance it is enough to multiply the speed by the time the signal from the satellite to a ground receiver. To calculate the time distributed signal each satellite navigation the system emits a precise time signals using exactly synchronized with system time atomic clock. Attached to work satellite receiver its clock is synchronized with system time, and at the further reception of signals is calculated delay between the time of radiation contained in the signal and time signal.
With this information, navigation receiver calculates antenna coordinate. All other parameters of movement (speed, the course, distance) is calculated on the basis of time measuring, which the object was spent moving between two or more points with defined coordinate.
The new system satellite navigation is the fact that it is not measured in time and the time interval between the time of sending the signal from the satellite and the time achieve a signal receiver antenna located on the object whose coordinate subject to measurement. Now act GPS and GLONASS.
Synchronization in digital communication systems
All the above use of reference signals frequency and time were aimed at the solution of the problem generation and transmission of time signals, that is to solve problems in other areas of technology. However, the solution of the problem of high-precision measurements time and transmit corresponding signals in the last time had a significant impact on the communication technology. With the transition to digital methods of signal transmission became urgent problem with synchronization in communication networks which also is associated with the time dimension.
The main purpose of nelwork synchronization is to ensure the installation and maintenance of certain and maintaining a certain clock frequency digital signals. The most common type of synchronization is the frequency synchronization, which means consistency generators of different digital devices in the network by frequency. I should be noted that the application of frequency synchronization does not constitute a waiver of the time dimension because size of frequency determine size period, measured in units of time. Therefore, the device provides a clock synchronization are called "chronograph sources", "timers".
To ensure reliable synchronization apply: the primary PEG - primary reference generator (provides reception signal reference the clock frequency for the synchronization of the entire digital network) and VZG- secondary oscillator (provides restoration of the quality of transmitted across the network clock signal and the distribution of the output signal on required quantity electrical outlet.
The importance of accurate maintenance of the nominal value clock frequency signals using PEG and VZG has caused the emergence of the international classification (reference generators) timers. The transmission frequency of the State standard of Russia to the place the comparison is carried out through different radio stations with signals the exact time signal and reference frequencies. The time signals and the reference signals of frequencies passed on frequencies 66(6) kHz and 50 kHz are available in two radio stations located near the cities of Moscow and Irkutsk, at that the transceiver 66(6) kHz covers and provides the European part of CIS and 50 kHz Asian. Thus the dimension of time and communication technology has had a significant mutual influence, what was of great importance for their development.
References
1. House.D. On Greenwich time and the discovery of longitude. World, 1983.
2. Resolution of the Government RF from 23 March 2001 year N 225 "On approval of the regulations on public service time and frequency parameter definitions Earth" (with changes from 2 August 2005 year, 10 March, 2 September 2009 year, 8 September 2010 year, 31 January 2012 year).
3. Resolution of the Government RF from 03.06.2011, N107-FZ "Calculation time".
СВЯЗЬ И РЕШЕНИЕ ЗАДАЧИ ИЗМЕРЕНИЯ ВРЕМЕНИ
Аджемов Артём Сергеевич, Хромой Борис Петрович, МТУСИ, Москва, Россия
Человек столкнулся с необходимостью измерений в глубокой древности, на раннем этапе своего общественного развития - в практической жизни: в земледелии, строительстве жилья, дворцов, храмов, в торговле. Людям потребовалось измерять расстояния, площади, объемы, веса, и, разумеется, время. Измерения длины, площади и объема, которые были необходимы при строительстве, стимулировали развитие математики. Измерение площади дало толчок появлению такой науки как "геометрия", поскольку необходимо было определять площади треугольников, окружности и других более сложных фигур. Площадь прямоугольника определяется произведением длин сторон. Эта задача решается с помощью арифметики, которая получила толчок развития от решения практических задач.
Литература
1. Хауз. Д. Гринвическое время и открытие долготы. Мир, 1983.
2. Постановления Правительства РФ от 23 марта 2001 г. № 225 "Об утверждении Положения о Государственной службе времени, частоты и определения параметров вращения Земли" (с изменениями от 2 августа 2005 г., 10 марта, 2 сентября 2009 г., 8 сентября 2010 г., 31 января 2012 г.)
3. Постановление Правительства РФ от 03.06.2011 г №107-ФЗ "Об исчислении времени".
T-Comm ^м 9. #12-2015
