CN113093235A - High-precision time synchronization system and method for devices in tunnel - Google Patents
High-precision time synchronization system and method for devices in tunnel Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 claims abstract description 50
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/33—Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS
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- G—PHYSICS
- G04—HOROLOGY
- G04R—RADIO-CONTROLLED TIME-PIECES
- G04R20/00—Setting the time according to the time information carried or implied by the radio signal
- G04R20/02—Setting the time according to the time information carried or implied by the radio signal the radio signal being sent by a satellite, e.g. GPS
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
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Abstract
The invention provides a high-precision time synchronization system and method for tunnel inner devices, which comprises a tunnel outer device and a plurality of tunnel inner devices, wherein the tunnel outer device is provided with a GPS/BDS antenna to receive signals of a GPS and a Beidou satellite positioning system for time synchronization, the tunnel outer device is connected with one tunnel inner device through a time synchronization optical fiber, the other tunnel inner devices are sequentially connected through the time synchronization optical fiber, cascade connection is formed among the tunnel inner devices, and each tunnel inner device sends a time synchronization signal to the next tunnel inner device. The invention can effectively solve the problem of time synchronization of the in-tunnel device, so that the in-tunnel device can also have a high-precision clock under the condition that the in-tunnel device cannot obtain satellite signals, and the realization of an application function with high requirement on clock precision is ensured.
Description
Technical Field
The invention belongs to the technical field of time synchronization devices, and particularly relates to a high-precision time synchronization system and method for an in-tunnel device.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In some practical applications such as power system cable partial discharge detection, transmission line fault location and the like, the device must have a high-precision clock to realize corresponding functions, and the high-precision clock is a key technology of the device. At present, the means for realizing the high-precision clock mainly depends on a time service signal provided by a GPS or Beidou satellite navigation system, and the high-precision synchronous clock can be obtained by utilizing the time service signal to correct the time. Because the signals of the GPS and the Beidou satellite navigation system cannot be received in the tunnel, the device in the tunnel is difficult to realize a high-precision clock.
Disclosure of Invention
The invention aims to solve the problems and provides a high-precision time tick system and a high-precision time tick method for the device in the tunnel.
According to some embodiments, the invention adopts the following technical scheme:
a high-precision time synchronization system for tunnel apparatuses comprises a tunnel outside apparatus and a plurality of tunnel apparatuses, wherein the tunnel outside apparatus is provided with a GPS/BDS antenna to receive signals of a GPS and a Beidou satellite positioning system for time synchronization, the tunnel outside apparatus is connected with one tunnel apparatus through time synchronization optical fibers, the rest tunnel apparatuses are sequentially connected through the time synchronization optical fibers, cascade connection is formed among the tunnel apparatuses, and each tunnel apparatus sends time synchronization signals to the next tunnel apparatus.
The technical scheme provides a unilateral time synchronization system.
The high-precision time synchronization system comprises two tunnel outer devices and a plurality of tunnel inner devices, wherein the tunnel inner devices are sequentially connected through time synchronization optical fibers, cascade connection is formed among the tunnel inner devices, the tunnel inner devices located at the end parts of the cascade structure are respectively connected with the tunnel outer devices through the time synchronization optical fibers, and the tunnel outer devices are provided with GPS/BDS antennas to receive signals of a GPS and a Beidou satellite positioning system to perform time synchronization.
The technical scheme provides a bilateral time synchronization system.
Alternatively, both devices outside the tunnel may send time tick signals to the device inside the tunnel at given time intervals, and the device inside the tunnel automatically performs time tick according to the first time tick signal received in the time interval and automatically ignores the time tick signal sent from the other side in the time interval.
As a general rule, both the single-sided and the double-sided time synchronization systems have the following features:
as an alternative embodiment, the pair of time optical fibers includes a pair of optical fibers, each for transmitting and receiving signals.
In an alternative embodiment, the intra-tunnel device and the extra-tunnel device each comprise at least two optical ports, each of which is connected to a respective one of the optical fibers of the pair of optical fibers for transmitting/receiving signals.
As an alternative embodiment, the system for high-precision time synchronization of the in-tunnel device further comprises a plurality of optical fiber distribution boxes, wherein a plurality of ports are arranged on the optical fiber distribution boxes, part of the ports are connected with the optical cables, and the corresponding ports are connected with the corresponding optical ports of the out-tunnel device/the out-tunnel device through the pigtails.
The time setting method based on the time setting system comprises the following steps:
(1) the tunnel device receives the time tick signals, records the time t2 when the time tick signals are received, and acquires the time t1 when the time tick signals are sent by the time tick device from the received time tick signals;
(2) the tunnel device sends a response message and records the sending time t 3;
(3) the opposite side receives the response message, records the receiving time t4, and sends a message to inform the tunnel inner device of the value of t 4;
(4) calculating the time difference between the two in-tunnel devices to be delta t according to the four time values of t1, t2, t3 and t 4;
(5) and adding delta t to the local time of the timed in-tunnel device for clock correction.
As an alternative embodiment, the intra-tunnel device switches the time tick state of the device according to different time tick signals.
As an alternative embodiment, the intra-tunnel device includes three time setting states, that is, an unpaired state where neither optical port receives a time setting signal, a normal antenna state and receives a satellite signal, a satellite time setting state where both optical ports are in a transmitting state, an open antenna, and a single optical port time setting state where one optical port is in a receiving state and receives a time setting signal.
As an alternative, t2 is the time recorded at the local time of the device within the tunnel and t1 is the time recorded at the local time of the device sending the time tick.
As an alternative embodiment, a specific method for calculating the time difference between two in-tunnel devices includes: Δ t ═ ((t1+ t4) - (t2+ t 3))/2.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention provides a high-precision time synchronization method of an in-tunnel device, which can effectively solve the time synchronization problem of the in-tunnel device, so that the in-tunnel device can also have a high-precision clock under the condition that a satellite signal cannot be obtained, and the realization of an application function with high requirement on the clock precision is ensured.
(2) The tunnel internal timing system provided by the invention can enable the tunnel internal device to have the same clock precision as the tunnel external device, and the clock error can be controlled within 100ns, thereby completely meeting the requirements of functions such as cable fault location, cable partial discharge detection and the like and having very high practical value.
(3) The device can utilize the clock of the device outside the tunnel at one side to clock time so as to form a single-side time-clocking system. And a clock of the device outside the tunnel at two sides can be used for time synchronization to form a double-side time synchronization system. The bilateral time synchronization system can be used for both sides for time synchronization and for standby, and has higher reliability.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic diagram of a single-side time synchronization system according to the present invention;
FIG. 2 is a schematic diagram of a single-sided time-tick connection of the present invention;
FIG. 3 is a schematic structural diagram of a double-sided time synchronization system according to the present invention;
FIG. 4 is a schematic diagram of a double-sided time tick cable according to the present invention;
fig. 5 is a diagram of the device of the present invention versus time.
The specific implementation mode is as follows:
the invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only terms of relationships determined for convenience of describing structural relationships of the parts or elements of the present invention, and are not intended to refer to any parts or elements of the present invention, and are not to be construed as limiting the present invention.
In the present invention, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be determined according to specific situations by persons skilled in the relevant scientific or technical field, and are not to be construed as limiting the present invention.
Example one
A single-side time setting system is provided, and a schematic diagram of the single-side time setting system is shown in fig. 1. And a GPS/BDS antenna is arranged outside the tunnel, and is used for receiving signals of a GPS and a Beidou satellite positioning system and carrying out time synchronization. The tunnel external device is connected with the 1 st device in the tunnel through specially laid optical fibers (two pairs, one pair is used for receiving and sending, and the other pair is standby), the time tick signal of the 1 st device in the tunnel is provided by the tunnel external device, namely the tunnel external device sends the time tick signal to the 1 st device in the tunnel through the optical fibers, and the 1 st device completes the time tick according to the time tick signal provided by the tunnel external device. The 1 st device in the tunnel is connected with the 2 nd device in the tunnel through the specially laid optical fiber, and sends the time tick signal to the 2 nd device through the optical fiber, and the 2 nd device completes the time tick according to the time tick signal provided by the 1 st device. By analogy, all devices in the tunnel are connected with each other by adopting the time-tick optical fibers to form cascade connection, and each device sends a time-tick signal to the next device.
The following describes a method for connecting a single-side time-setting system, and fig. 2 shows a fiber connection diagram of the single-side time-setting system. The time-setting optical fibers among the devices are connected by adopting 4-core optical cables, the 4-core optical cables are connected into an optical fiber distribution box, the optical fiber distribution box can be connected into two 4-core optical cables, one optical cable enters one optical cable and the other optical cable exits one optical cable, the optical cable enters the inside and is connected to the ports 1-4, and the optical cable exits one optical cable and is connected to the ports 5-8. Each device provides two optical ports: optical port 1 and optical port 2, each optical port has two interfaces of Receiving (RD) and Transmitting (TD).
As shown in fig. 2, the "out" of the fiber organizer of the device outside the tunnel is connected to the "in" of the fiber organizer of the 1 st device in the tunnel via the 4-core cable, the "out" of the fiber organizer of the 1 st device in the tunnel is connected to the "in" of the fiber organizer of the 2 nd device in the tunnel via the 4-core cable, and so on.
As shown in fig. 2, "TD" of the optical port 2 of the device outside the tunnel and "5" of the optical fiber distribution box are connected by pigtails, and "RD" of the optical port 2 and "6" of the optical fiber distribution box are connected by pigtails. Connecting the 'TD' of the optical port 1 in the tunnel with the '2' of the optical fiber distribution box through a tail fiber, and connecting the 'RD' of the optical port 1 with the '1' of the optical fiber distribution box through the tail fiber; the TD of the optical port 2 in the tunnel is connected with the 5 of the optical fiber distribution box through a tail fiber, and the RD of the optical port 2 is connected with the 6 of the optical fiber distribution box through a tail fiber. The last device in the tunnel is only required to be connected with the light interface 1.
Example two
A double-sided time synchronization system is provided, and a schematic diagram of the system is shown in fig. 3. And the devices on the two sides outside the tunnel are provided with GPS/BDS antennas for receiving pulses of a GPS and a Beidou satellite positioning system and timing. The extra-tunnel devices are connected to the intra-tunnel devices by specially laid optical fibres (two pairs, one pair for transceiving and one pair for standby), and the intra-tunnel devices are also connected to each other by specially laid optical fibres. In the double-side time tick system, the devices on both sides outside the tunnel can send time tick signals to the device in the tunnel at a given time interval (about 3 seconds), and the device in the tunnel automatically performs time tick according to the first time tick signal received in the time interval and automatically ignores the time tick signal sent from the other side in the time interval. After receiving the 1 st time tick signal and automatically performing time tick, the device in the tunnel sends the time tick signal to an adjacent device through another optical port. The double-side time synchronization system has no fixed time synchronization direction, the time synchronization is carried out by using the time synchronization signal received firstly in a given time synchronization interval, and the time synchronization signal at the other side is not received once the time synchronization signal is received.
The following describes a connection method of the double-sided time synchronization system, and fig. 4 shows an optical fiber connection diagram of the double-sided time synchronization system. The wiring of the double-side time synchronization system is basically the same as that of the single-side time synchronization system, and the wiring can be carried out from one side of the tunnel to the other side in sequence. As shown in fig. 4, the "out" of the fiber distribution box of the device outside the tunnel on one side is connected to the "in" of the fiber distribution box of the 1 st device in the tunnel via the 4-core cable, the "out" of the fiber distribution box of the 1 st device in the tunnel is connected to the "in" of the fiber distribution box of the 2 nd device in the tunnel via the 4-core cable, and the like are performed in the tunnel. The outlet of the optical fiber distribution box of the last device in the tunnel is connected with the inlet of the optical fiber distribution box of the device outside the tunnel on the other side through the 4-core optical cable.
As shown in fig. 4, "TD" of the optical port 2 of the device outside the one tunnel and "5" of the optical fiber distribution box are connected by the pigtail, and "RD" of the optical port 2 and "6" of the optical fiber distribution box are connected by the pigtail. Connecting the 'TD' of the optical port 1 in the tunnel with the '2' of the optical fiber distribution box through a tail fiber, and connecting the 'RD' of the optical port 1 with the '1' of the optical fiber distribution box through the tail fiber; the TD of the optical port 2 in the tunnel is connected with the 5 of the optical fiber distribution box through a tail fiber, and the RD of the optical port 2 is connected with the 6 of the optical fiber distribution box through a tail fiber. The TD of the optical port 1 of the device outside the tunnel at the other side is connected with the 2 of the optical fiber distribution box through the tail fiber, and the RD of the optical port 1 is connected with the 1 of the optical fiber distribution box through the tail fiber.
Through the embodiment, the time synchronization in the tunnel can be carried out by utilizing the clock of the device outside the tunnel at one side, so that a single-side time synchronization system is formed. And a clock of the device outside the tunnel at two sides can be used for time synchronization to form a double-side time synchronization system. Because the bilateral time synchronization system can be used for time synchronization at two sides for standby, the reliability of the bilateral time synchronization system is higher than that of the unilateral time synchronization system.
Whether the single-sided system provided by the first embodiment or the double-sided system provided by the second embodiment, the time-tick status can be collectively represented by the status diagram shown in fig. 5 for the device outside the tunnel or the device inside the tunnel. For the four cases, the following are respectively: (1) the time setting state comprises a no time setting state, (2) a satellite time setting state, (3) an optical port 1 time setting state and (4) an optical port 2 time setting state. When a certain condition is changed, the time tick state is correspondingly switched. The meaning of the various time-setting states and the conditions for state switching are described below.
Meaning to time State
(1) Time-out state
When the antenna is in an open state (no GPS antenna is installed), and both optical ports 1 and 2 are in a receiving state but no time tick signal is received, the device is in a "time tick-free state".
(2) Satellite time setting state
When the antenna state is normal and a satellite signal is received, and optical ports 1 and 2 are in the transmission state, the apparatus is in the "satellite time synchronization state". In this state, the device clock is clocked by means of the satellite signal.
(3) Optical port 1 time synchronization state
When the antenna is in an open circuit state (no GPS antenna is installed), and optical port 1 is in a receiving state and receives a time tick signal, and optical port 2 is in a transmitting state, the device is in an "optical port 1 time tick state". In this state, the device clock is clocked by the clock signal received via the optical port 1.
(4) Optical port 2 time setting state
When the antenna is in an open circuit state (no GPS antenna is installed), and optical port 2 is in a receiving state and receives a time tick signal, and optical port 1 is in a transmitting state, the device is in an "optical port 2 time tick state". In this state, the device clock is clocked by the clock signal received via the optical port 2.
Switching of time setting states
The time tick state is switched among 4 states according to different occurrence signals. When the optical interface 2 is in the "time synchronization state of the optical interface 2", the satellite signal is received, that is, the satellite signal is switched to the "time synchronization state of the satellite", the optical interface 1 receives the time synchronization signal, that is, the time synchronization signal is switched to the "time synchronization state of the optical interface 2"; when the satellite is in the satellite time-setting state, the lost satellite signal is switched to the time-setting-free state; when the optical port 1 is in the time setting state, the satellite signal is received, namely the satellite time setting state is switched to, and when the optical port 1 time setting signal disappears, the optical port 1 time setting state is switched to the time setting-free state; when the optical port 2 is in the "time setting state at optical port 2", the satellite signal is received, that is, the satellite time setting state is switched to, and when the optical port 2 time setting signal disappears, the satellite time setting state is switched to the "time setting free state".
The time synchronization of the in-tunnel device is carried out according to the clock signal sent by the out-of-tunnel device or the adjacent device, although the communication time between the two devices can be greatly reduced by adopting optical fiber connection, the propagation time of the time synchronization signal on the optical fiber can not be ignored for the high-precision time synchronization, otherwise, the clock precision has larger error.
Example three:
providing a time synchronization method which can be adopted by the first embodiment and the second embodiment, and comprising the following steps:
(1) the tunnel device receives the time tick signal, records the time t2 when the time tick signal is received (t2 is the time recorded according to the local time of the tunnel device), and acquires the time t1 when the time tick signal is sent by the sending time tick device from the received time tick signal (the time tick signal sending device embeds the sending time t1 in the communication frame of the time tick signal, and t1 is the time recorded according to the local time of the time tick signal sending device).
(2) The tunnel device sends a response message and records the sending time t 3.
(3) The counterpart receives the response message and records the receiving time t 4. And sends a message informing the tunneled device of the value of t 4.
(4) The intra-tunnel device obtains four time values t1, t2, t3, t4, where t2 and t3 are recorded as the local time of the intra-tunnel device being time stamped and t1 and t4 are recorded as the local time of the device sending the time tick. Let Δ t be the time difference between the two devices, and considering that the uplink and downlink communication times of the optical fiber channel are completely the same, Δ t is ((t1+ t4) - (t2+ t 3))/2.
(5) And adding delta t to the local time of the timed in-tunnel device for clock correction.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (10)
1. A high-precision time synchronization system for an in-tunnel device is characterized in that: the GPS/BDS antenna is arranged outside the tunnel and used for receiving signals of a GPS and a Beidou satellite positioning system to time, the tunnel outside device is connected with one of the tunnel devices through time-setting optical fibers, the rest tunnel devices are sequentially connected through the time-setting optical fibers, cascade connection is formed among the tunnel devices, and each tunnel device sends time-setting signals to the next tunnel device.
2. A high-precision time synchronization system for an in-tunnel device is characterized in that: the device comprises two tunnel outer devices and a plurality of tunnel inner devices, wherein the tunnel inner devices are sequentially connected through time synchronization optical fibers, cascade connection is formed among the tunnel inner devices, the tunnel inner devices located at the end parts of a cascade structure are respectively connected with one tunnel outer device through the time synchronization optical fibers, and the tunnel outer devices are provided with GPS/BDS antennas to receive signals of a GPS and a Beidou satellite positioning system for time synchronization.
3. The high-precision time setting system of the in-tunnel device as claimed in claim 2, wherein: the devices at two sides outside the tunnel can send time tick signals to the device in the tunnel according to a given time interval, the device in the tunnel automatically performs time tick according to the first received time tick signal in the time interval, and automatically ignores the time tick signals sent from the other side in the time interval.
4. The high-precision time synchronization system of the in-tunnel device as claimed in claim 1 or 2, characterized in that: the time-setting optical fiber comprises a pair of optical fibers which are respectively used for receiving and transmitting signals.
5. The high-precision time synchronization system of the in-tunnel device as claimed in claim 1 or 2, characterized in that: the device comprises at least two optical ports, and each optical port is connected with an optical fiber for receiving/transmitting signals in the optical fiber at the time of alignment.
6. The high-precision time synchronization system of the in-tunnel device as claimed in claim 1 or 2, characterized in that: the system for high-precision time synchronization of the devices in the tunnel further comprises a plurality of optical fiber distribution boxes, wherein a plurality of ports are arranged on each optical fiber distribution box, part of the ports are connected with the optical cables, and the corresponding ports are connected with the corresponding optical ports of the devices outside the tunnel/the devices outside the tunnel through tail fibers.
7. The time synchronization method of the time synchronization system according to any one of claims 1 to 6, wherein: the method comprises the following steps:
(1) the tunnel device receives the time tick signals, records the time t2 when the time tick signals are received, and acquires the time t1 when the time tick signals are sent by the time tick device from the received time tick signals;
(2) the tunnel device sends a response message and records the sending time t 3;
(3) the opposite side receives the response message, records the receiving time t4, and sends a message to inform the tunnel inner device of the value of t 4;
(4) calculating the time difference between the two in-tunnel devices to be delta t according to the four time values of t1, t2, t3 and t 4;
(5) and adding delta t to the local time of the timed in-tunnel device for clock correction.
8. The time synchronization method as claimed in claim 7, wherein: and the device in the tunnel switches the time setting state of the device according to the difference of the time setting signals.
9. The time synchronization method as claimed in claim 8, wherein: the tunnel device comprises three time setting states, namely a non-time setting state that two optical ports do not receive time setting signals, an antenna state is normal and receives satellite signals, the two optical ports are in a satellite time setting state in a sending state, the antenna is open, and one optical port is in a receiving state and receives a single optical port time setting state of the time setting signals.
10. The time synchronization method as claimed in claim 7, wherein: t2 is the time recorded by the local time of the device in the tunnel, t1 is the time recorded by the local time of the device sending the time tick; the specific method for calculating the time difference between the two devices in the tunnel comprises the following steps: Δ t ═ ((t1+ t4) - (t2+ t 3))/2.
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