RU2547662C1 - Method of comparison of time scales and device for its implementation - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: device contains two parts located on objects at distance from each other, and contains on the first object the events timer with connected to it generator of time scale formation for this object and receiver of optical pulses, optical pulses generator connected to input of the splitters-couplers unit. At that the splitters-couplers unit contains fibre optic splitter connected with the fibre optic coupler and splitter. At that the fibre optic coupler is connected with input of receiver of optical pulses and with splitter connected also with fibre optic communication line that connects two remote objects, information communication system of time intervals connected with events timer of the first object. The second object contains the events timer connected with generator of time scale generation of this object, receiver of the optic pulses of the second object connected by the fibre optic communication line with the first object, as well as with events timer of the second object, information communication system of time intervals of this object connected with events timer of the second object.

EFFECT: increased accuracy of comparison or synchronisation due to use of signals in the optical range, increased reliability and operational efficiency due to use of the fibre optic communication line, as well as possibility to compare or to synchronise time scales between objects at significant distance from each other in arbitrary points due to use of only one fibre optic cable of optional length.

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Description

A method and device for comparing and synchronizing time scales between a ground station and a satellite using single-sided and two-sided satellite laser ranging (M.A. Sadovnikov, A.A. Fedotov, V.D. Shargorodsky High-precision single-sided laser ranging: state and prospects of application in GLONASS, Proceedings of the Institute of Applied Astronomy RAS, issue 23, 2012), which are the closest analogues to the proposed ones and are selected as prototypes; between ground points by transmitting, receiving and re-emitting, receiving a radio pulse (P.I. Tanzai, V.G. Kornienko. Experimental studies of the accuracy of synchronization of time scales at spatially separated points by the method of interrogation radar, TUSUR Reports, No. 2 (18), part 2, December 2008); between ground stations by transmitting optical pulses through an optical fiber using an optical fiber loop (M. A. Sadovnikov, A. A. Fedotov, V. D. Shargorodsky. High-precision single-sided laser ranging: state and prospects of application in GLONASS, Proceedings of the Institute of Applied Astronomy RAS , issue 23, 2012).

Of the known methods and devices, the closest to the proposed are the method and device for comparing or synchronizing time scales between a ground station and a satellite using one-sided and two-sided satellite laser ranging (M.A. Sadovnikov, A.A. Fedotov, V.D. Shargorodsky High-Precision single-sided laser ranging: state and prospects of application in GLONASS, Proceedings of the Institute of Applied Astronomy RAS, issue 23, 2012), which are selected as prototypes.

A device for comparing and synchronizing time scales between a ground station and a satellite using one-sided and two-sided satellite laser ranging contains at the ground station leading (reference) clocks; a laser transmitter emitting optical pulses; an event timer that records the time of radiation, reception of reflected pulses in the time scale of a ground station; transmitting telescope; a generator on board the satellite, forming a satellite timeline; reflector on board the satellite; laser pulse receiver on board the satellite; an on-board event timer that records the time of arrival of pulses in the satellite clock; receiving telescope of reflected laser pulses at a ground station; a photodetector that records the arrival time of the reflected laser pulses in the time scale of the leading clock; an additional channel of information for transmitting data on the time of arrival of pulses in the time scale of one of the points to another point.

The main advantage of the method of single-sided and double-sided satellite laser ranging is that it eliminates the need for data on the length of the signal path. Therefore, its accuracy mainly depends on the technical parameters of the ground-based transmitter and receiver, on-board receiver, time interval measurement equipment.

The main disadvantage of this device is that the atmosphere is the transmission medium for optical pulses. A change in the transparency of the atmosphere leads to significant differences in the power level of the received signals, which reduces the accuracy of the timing of the reception of pulses to time scales. At a certain level of attenuation of signal power in the atmosphere, the operation of the device becomes impossible. Moreover, the duration of such periods of inoperability in the Russian Federation can be many days.

Local fluctuations in air density under any weather conditions also lead to a change in the power level of the received signals; to combat this, one has to use expensive receiving and transmitting telescopes with the largest apertures.

The different location of the receiver and reflector on board the satellite leads to a systematic error in the comparison of time scales.

It is possible to implement the data of the method and device between ground points, while direct visibility between them is necessary, which in modern building conditions is usually not provided. The operability of such a device also depends very much on the state of the atmosphere.

Also known is a method and device for comparing and synchronizing time scales between ground points using interrogation radar.

The device contains signal generators of the leading and driven time scales, a leading point radio transmitter emitting a radio pulse, an event timer (time interval meter) that fixes the time of the radio pulse emission in the leading point time scale. A radio pulse is received by the radio receiver of the slave item, an event timer fixes the time of receiving the radio pulse in the time scale of the slave item. A response pulse is emitted by the transmitter of the slave station with some delay, which is received by the receiver of the master station, the arrival time is recorded by the event timer, information about the delay between the pulses sent and received by the master station is transmitted to the slave station via an additional communication channel.

The disadvantages of this analog device include the use of pulses in the radio range. A significantly lower frequency of the carrier pulses compared with the optical range provides a deliberately lower accuracy of the comparison of time scales. Other disadvantages are the need for re-emission of the pulse, the greater susceptibility of radio paths to the influence of interference, the dependence of the travel time of the signals on the state of the atmosphere and the earth's surface.

Also known is a method and device for comparing and synchronizing time scales between ground points by transmitting optical pulses through an optical fiber using an optical fiber loop.

The device comprises a signal generator of a standard time scale, a transmitter of the leading point emitting a time stamp in the form of an optical pulse in the fiber optic communication line from the leading point to the slave. The pulse is received by the photodetector of the slave item, part of the pulse energy is sent through the fiber optic splitter to the fiber optic cable, parallel to the main line and having a length strictly equal to the two lengths of the main line, fed to the photodetector of the slave item. The event timer at the slave item records the arrival time of pulses transmitted along the main line and through the loop, using the computer determines the time correction to the received time stamp, equal to the time the pulse passed along the main line.

The disadvantages of this analog device include the use of a fiber optic cable, which requires three optical fibers of equal length between points. Under the influence of various physical influences during operation, the fiber lengths can vary in different ways, which leads to a decrease in the accuracy of the transmission of the time scale. In addition, the requirement of equal lengths of three fibers does not allow the use of so-called “dark” fibers rented from telecom operators in the device.

The technical result obtained from the implementation of the method of comparing time scales at two remote ground objects is to increase the accuracy of comparisons or synchronization through the use of signals in the optical range, to increase reliability and efficiency through the use of a fiber optic communication line, as well as the possibility of comparing or synchronizing time scales between objects located at a considerable distance at arbitrary points due to the use of only one optical fiber of arbitrary length, including "Dark" fiber rented from operators of publicly available communication networks.

This technical result is achieved due to the fact that the method of comparing time scales in the form of 1PPS signals at two distant objects consists in the fact that a sequence of n optical pulses is emitted from the optical pulses by the optical pulse generator during the comparison and the emission time of the ith optical pulse is recorded pulse in the time scale of this object (t _i ), optical pulses are sent along the fiber optic communication line connecting remote objects, record the time of arrival of optical pulses to the second object in the time scale e of the object (τ _i ² ), at the time of arrival of each optical pulse to the second object in the fiber optic communication line from this object to the first object is sent by reflecting part of the energy of the optical pulse from the end of the optical fiber communication line or using the reverse optical pulse generator pulse, record the arrival time of the return optical pulses to the first object in its time scale (τ _i ¹ ), determine the discrepancy in the time scales of objects Δt by the formula:

where n is the number of optical pulses during the comparison,

τ _i ² - the measured time of arrival of the i-th optical pulse in the time scale of the second object,

τ _i ¹ - the measured arrival time of the reverse i-th optical pulse in the time scale of the first object,

t _i is the measured radiation time of the i-th optical pulse in the time scale of the first object.

Averaging the data during the comparison for each i-th pulse provides an increase in the accuracy of comparison.

A feature and advantage of this method is that the optical pulse generator can be located on the second object, while the optical pulses are sent via the fiber optic communication line to the first object, the return pulses are sent to the second object, the time of sending the optical pulse and the arrival of the return in the time scale is recorded of the second object, the time of arrival of the optical pulse from the second object to the first in the time scale of the first object is recorded, the discrepancy of the time scales is determined from the measured values Yeni objects.

The technical result obtained from the introduction of a device for comparing time scales of distant objects is to increase the accuracy of comparison or synchronization of time scales between ground points through the use of optoelectronic modules, event timers, generators with maximum bandwidth, the use of an existing commercially available element base with 10 bandwidths GHz and more, which allows to achieve the accuracy of comparisons up to 100 ps, as well as increase the distance between the objects at which the comparison cal time through the use of a semitransparent mirror or reverse pulse generating system.

This technical result is achieved due to the fact that the device for comparing the time scales of distant objects, consisting of two components located on objects distant from each other, contains an event timer on the first object with a generator for generating a time scale for this object and an optical receiver pulses, an optical pulse generator connected to the input of the combiner splitter block, wherein the combiner splitter block includes an optical fiber splitter, connected with a fiber optic combiner and splitter, the fiber combiner connected to the input of the optical pulse receiver and a splitter that is also connected to the fiber optic communication line that connects two remote objects, a time interval information transmission system connected to the event timer of the first object, the second object contains an event timer connected to a generator for forming a time scale of this object, a receiver of optical pulses of the second object connected by a fiber optic line communication with the first object, as well as with the event timer of the second object, a system for transmitting information about time intervals connected to the event timer of the second object.

To increase the power of the return optical signal from the second object to the first and, consequently, increase the possible distance between the objects, it is possible to use a translucent mirror placed in the connector of the optical pulse receiver of the second object or the generator of reverse optical pulses on the second object.

The second object of the device may further comprise an inverse optical pulse generator and an additional optical fiber combiner, the output channel of the optical pulse receiver of the second object being connected to a reverse optical pulse generator, the output of which is connected to an optical fiber combiner, one of the inputs of which is connected to the input of the optical pulse receiver, and the output with fiber optic communication line.

A device for comparing time scales of remote objects on one of the objects may include a computer connected to an information transmission system for automatically comparing time scales of remote objects. The computer can be connected to a generator that forms the time scale of this object, to synchronize the time scales of remote objects.

In a device for comparing the time scales of distant objects, an electric pulse generator can be used on one of the objects as an optical pulse generator connected to an electron-optical converter generating optical pulses, and the electric pulse generator is also connected to the event timer of this object. In this case, the generator forming the time scale of this object can be connected to an electric pulse generator.

In the device for comparing time scales of remote objects, a fiber-optic communication line connecting the first and second objects can be used using spectral multiplexing technology as an information transmission system.

The invention is illustrated by drawings.

Figure 1 presents a diagram of a device for implementing the method of comparing the time scales of remote objects;

figure 2 presents a diagram of a device with a generator of reverse optical pulses;

figure 3 presents a diagram of a device with automatic comparison and synchronization of time scales of remote objects;

figure 4 presents a timing diagram of the operation of the device when the location of the optical pulse generator on the first object.

Figure 1 shows a diagram of a device for comparing the time scales of remote objects, which contains an event timer 1 on the first object, an oscillator 2 for generating a time scale for this object, and an optical pulse receiver 3. The optical pulse generator 4 at the first object is connected to the input of block 5 of combiner splitters. Block 5 of combiner splitters consists of a fiber optic splitter 6 connected to a fiber optic combiner 7 and a splitter 8, while the fiber combiner 7 is connected to the input of the optical pulse receiver 3 and a splitter 8, which is also connected to the fiber optic communication line 9, which connects two remote objects . The device comprises a system for transmitting information 10 about time intervals (for example, an Ethernet network, a wireless network, etc.) connected to timers 1 and 11 of events of the first and second objects to calculate the discrepancy of the time scales of objects.

The second object contains an event timer 11, an oscillator 12 for generating a time scale for this object, and an optical pulse receiver 13 of the second object, which is connected to the fiber optic communication line 9, and a system for transmitting information 10 about time intervals attached to it.

To increase the power of the reverse optical signal coming from the second object to the first, and, therefore, increase the possible distance between the objects, it is possible to use a translucent mirror (not shown in the drawing) located in the connector of the receiver 13 of the optical pulses of the second object.

Figure 2 shows a diagram of a device with a generator of reverse optical pulses 14, the electrical input of which is connected to the output of the receiver 13 of the optical pulses, and the fiber optic output through an additional fiber optic combiner 15 is connected to the fiber optic communication line 9.

Figure 3 shows a diagram of a device with automatic comparison and synchronization of time scales of objects. In this case, the optical pulse generator, consisting of an electric pulse generator 16 and an optoelectronic converter 17, a combiner splitter unit 5, a computer 18 for automatic comparison are located on the second object. The first object contains an event timer 1, associated with a generator for generating a time scale of the first object 2, an optical pulse receiver 3, associated with an optical fiber communication line 9, and a system for transmitting information about time intervals 10.

The second object contains an event timer 11 associated with a timeline generator for this object 12, an electric pulse generator 16 connected to an electron-optical converter 17 with an optical fiber output generating optical pulses, as well as with an event timer 11 and a second object timeline generator 12. The electron-optical converter 17 through a block of splitter-combiners 5 is connected to a fiber optic communication line 9. Computer 18 is connected to a system for transmitting information about time intervals lah 10, an event timer 11, a generator for generating a time scale of the second object 12.

The method of comparing time scales is implemented as follows.

A sequence of n optical pulses is emitted at the first object during the comparison, the radiation time of the i-th optical pulse is recorded in the time scale of this object (t _i ), optical pulses are sent along the fiber-optic communication line connecting the remote objects, the time of arrival of optical pulses is recorded on the second object in the timeline of this object (τ _i ² ), at the time of arrival of each optical pulse to the second object, an optical return pulse is fed to the first object in the fiber optic communication line from this object, fi coding the time of arrival of optical pulses to the first object in its time scale (τ _i ¹ ), determine the discrepancy of the time scales of objects Δt according to the formula:

where n is the number of optical pulses during the comparison,

τ _i ² - the measured time of arrival of the i-th optical pulse in the time scale of the second object,

τ _i ¹ - the measured arrival time of the reverse i-th optical pulse in the time scale of the first object,

t _i is the measured radiation time of the i-th optical pulse in the time scale of the first object.

Averaging the data during the comparison for each i-th pulse provides an increase in the accuracy of comparison.

A timing diagram of the operation of the device is shown in Figure 4, where A and B are the time scale of the first and second objects, respectively, t ^A and t ^B are second-time marks of the time scales of the first and second objects, respectively.

The optical pulse generator can also be located on the second object, while the optical pulses are sent via the fiber optic communication line to the first object, the return pulses are sent to the second object, the time of sending the optical pulse and the arrival of the return in the second time scale is recorded, the time of arrival of the optical pulse from the second object to the first in the time scale of the first object, the measured values determine the discrepancy of the time scales of objects.

The device implemented in accordance with figure 1, operates as follows.

The optical pulse from the optical pulse generator 4 is fed to the input of the splitter-combiner unit 5, passes through the splitter 6, some of the optical pulse power through the combiner 7 is fed to the optical pulse receiver 3 of the first object, the main part of the pulse power through the splitter 8 enters the fiber optic communication line 9. The electrical signal from the receiver 3 enters the optical pulse event timer 1 which fixes the optical pulse emission instant t _i in time scale of the first object, to form the generator 2 1PPS signal, the second label is also coming to the event timer 1. Information about the radiation point of i-th optical pulse on the data transmission system 10, for example an Ethernet network, a wireless network or other directed to the point of comparison scales distant objects time.

An optical pulse arriving via a fiber-optic communication line to a second object with a certain time delay τ _s arrives at the receiver 13 of the optical pulses of the second object, which converts it into an electrical signal supplied to the event timer 11. Also, the 1PPS signal from the generator is supplied to the event timer 11 12, forming the time scale of the second object, which allows you to determine the time τ _i ^{2 the} arrival of the optical pulse in the time scale of the second object. Information about the moment of arrival of the i-th optical pulse via the information transmission system (10) is sent to the point of comparison of the time scales of remote objects.

At the same time, part of the power of the optical pulse arriving at the second object is reflected from the end of the fiber or translucent mirror in the connector of the receiver 13 of the optical pulses of the second object and passes through the communication line 9 the opposite way. With a time delay strictly equal to the delay in the communication line with the direct passage of τ _s , the reflected pulse through the splitter 8 and combiner 7 is fed to the input of the receiver 3 of the optical pulses of the first object. The signal from the receiver 3 of the optical pulses is fed to the input of the event timer 1, which determines the time of arrival of the optical pulse τ _i ¹ in the time scale of the first object. Information about the moment of arrival of the i-th reverse optical pulse through the information transfer system 10 is sent to the point of comparison of the time scales of remote objects. Based on the data on the values of t _i , τ _i ¹ , τ _i ² determine the discrepancy of the time scales Δt of remote objects Δt by the formula:

where n is the number of optical pulses during the comparison,

τ _i ² - the measured time of arrival of the i-th optical pulse in the time scale of the second object,

τ _i ¹ - the measured arrival time of the reverse i-th optical pulse in the time scale of the first object,

t _i is the measured radiation time of the i-th optical pulse in the time scale of the first object.

The timing diagram of the operation of the device is shown in FIG. 4, where A and B are the time scale of the first and second objects, respectively, t ^A and t ^B are the second 1PPS marks of the time scales of the first and second objects, respectively.

The operation of the device implemented in accordance with figure 2, characterized in that at the time of arrival of the optical impulse to the second object from the receiver of optical pulses 13, the electric signal is additionally fed to the reverse pulse generator 14, which at this point in time generates an optical pulse coming through the fiber optic combiner 15 into a fiber optic communication line 9.

The device implemented in accordance with figure 3, operates as follows.

At the second object, an electric pulse generator 16 is used as an optical signal generator, connected to an electron-optical converter 17 generating optical pulses, the electric pulse generator being also connected to an event timer 11. A generator forming a time scale of the second object 12 is connected to an electric generator pulses and the signal 1PPS generator 16 generates a series of electrical pulses converted by the Converter 17 into a series of optical pulses received at the input unit a splitter-combiner 5. The optical pulse passes through the splitter 6, some of the power of the optical pulse through the combiner 7 enters the receiver of optical pulses 13 of this object, the bulk of the power of the pulse through the splitter 8 enters the fiber optic communication line 9. The time of sending the pulses is fixed in the scale time of this object using the event timer 11, the input of which also receives 1PPS signals from the generator 12, which forms the time scale of this object. The optical pulses transmitted through the optical fiber communication line 9 are received by the optical pulse receiver 3. The arrival time of each optical pulse in the time scale of the first object generated by the 1PPS 2 signal generator is recorded by the event timer 1 and sent to computer 18 through the information transmission system 10. Part of the power the optical pulse arriving at the first object is reflected from the end of the fiber or translucent mirror in the connector of the optical pulse receiver 3, passes through the optical fiber communication line 9 back to the second object and through the splitter 8 and combiner 7 enters the optical pulse receiver 13, the time of arrival of the return pulse is recorded by the event timer 11. Computer 18 receives information about the times of radiation of the direct and arrival of the return optical pulses in the time scale of the second object. Based on these data, time scales are automatically compared. On the communication channel between the computer 18 and the generator 12, automatic synchronization of time scales can occur by introducing the necessary delay into the time scale of the second object.

Claims (9)

1. A method of comparing time scales in the form of 1PPS signals at two remote objects generated by each object’s own generator by generating and registering optical signals, determining the time delay of the arrival of optical signals from one object to another by the method of processing data about the timing of signal recording, according to the results which compare time scales, which consists in the fact that at the first object, an optical pulse generator emits a sequence of n optical pulses during the comparison owls fixed time emission i-th optical pulse in a time scale of the object (t _i), the optical pulses sent over the fiber link connecting the remote objects, record the time of arrival of the optical pulses on the second object in the timeline of this object (τ _i ²⁾ , at the time of arrival of each optical pulse to the second object, a reverse optical pulse is sent to the first object in the fiber optic communication line from this object to the first object, the time of arrival of optical pulses to the first object is recorded in its time scale (τ _i ¹ ), determine the discrepancy of the time scales of objects Δt by the formula:
$$\Delta t=\frac{\mathrm{one}}{n}{\displaystyle \sum _{i=\mathrm{one}}^n({\tau }_i^2}-\frac{{\tau }_i^{\mathrm{one}}-t_i}{2})$$

where n is the number of optical pulses during the comparison,
τ _i ² - the measured time of arrival of the i-th optical pulse in the time scale of the second object,
τ _i ¹ - the measured arrival time of the reverse i-th optical pulse in the time scale of the first object,
t _i is the measured radiation time of the i-th optical pulse in the time scale of the first object. 2. A device for comparing the time scales of distant objects, consisting of two components located on objects distant from each other, containing on the first object an event timer with an generator for generating the time scale of this object and an optical pulse receiver, an optical pulse generator connected to the input of the combiner splitter block, wherein the combiner splitter block includes an optical fiber splitter connected to the optical fiber combiner and splitter, By the way, a fiber optic combiner is connected to the input of the optical pulse receiver and a splitter that is also connected to a fiber optic communication line that connects two remote objects, a time interval information transmission system connected to the event timer of the first object, the second object contains an event timer connected to the generation generator the time scales of this object, the optical pulse receiver of the second object, connected by a fiber-optic communication line with the first object, as well as with the WTO event timer th object information transmission system of the time intervals of the object connected to the timer event of the second object. 3. The device according to claim 2, characterized in that the optical fiber connector of the optical pulse receiver of the second object further comprises a translucent mirror to increase the power of the reverse optical signal. 4. The device according to claim 2, characterized in that the second object further comprises a reverse optical pulse generator and an additional optical fiber combiner, the output channel of the optical pulse receiver of the second object being connected to a reverse optical pulse generator, the output of which is connected to the optical fiber combiner, one of the inputs which is connected to the input of the receiver of optical pulses, and the output with a fiber optic communication line. 5. The device according to claim 2, characterized in that one of the objects has a computer connected to the information transmission system for automatically comparing the time scales of remote objects. 6. The device according to claim 5, characterized in that the computer is connected to a generator that forms the time scale of this object, to synchronize the time scales of remote objects. 7. The device according to claim 2, characterized in that as an optical pulse generator at one of the objects, an electric pulse generator is used, connected to an electron-optical converter forming optical pulses, and the electric pulse generator is also connected to the event timer of this object. 8. The device according to claim 7, characterized in that the generator forming the time scale of the object is connected to an electric pulse generator. 9. The device according to claim 2, characterized in that the optical fiber communication line connecting the first and second objects, using the technology of spectral multiplexing, is used as an information transmission system.

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