CN109039517B - Multi-node high-precision frequency synchronization method and system based on optical fiber network - Google Patents
Multi-node high-precision frequency synchronization method and system based on optical fiber network Download PDFInfo
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- CN109039517B CN109039517B CN201810909388.5A CN201810909388A CN109039517B CN 109039517 B CN109039517 B CN 109039517B CN 201810909388 A CN201810909388 A CN 201810909388A CN 109039517 B CN109039517 B CN 109039517B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
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- H04B10/25—Arrangements specific to fibre transmission
Abstract
The invention discloses a multi-node high-precision frequency synchronization method and a multi-node high-precision frequency synchronization system based on an optical fiber network, which are characterized in that a one-wavelength optical signal bidirectional half-duplex mode is adopted to measure the time deviation between a master node and a slave node in real time, a real-time compensation value is obtained according to a compensation algorithm and is used for carrying out time delay compensation on a frequency signal received by the slave node through another wavelength optical signal, and the purpose of keeping high-precision synchronization between the frequency signal of the slave node and the frequency signal of the master node is achieved, so that the aim of multi-node high-. The time deviation between the master node and the slave node is measured by adopting a bidirectional half-duplex mode of optical signals with the same wavelength, and the time delay asymmetry caused by environmental factors such as temperature and the like in the bidirectional transmission process of different wavelengths in the traditional measuring method can be eliminated, so that the precision of the time deviation measurement between the master node and the slave node is improved.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a multi-node high-precision frequency synchronization method and a multi-node high-precision frequency synchronization system based on an optical fiber network.
Background
With the continuous development of communication, navigation, astronomical observation, electric power and traffic systems and scientific research, the requirement on the synchronization quality of frequency signals is higher and higher, and the requirement on the high-precision frequency synchronization of multiple nodes is stronger. For example, in astronomical observation, an antenna array of an astronomical telescope needs a high-stability frequency signal to ensure the synchronization of receiving; high-precision frequency synchronization is also needed among multiple base radar stations to improve the detection precision.
The optical fiber has the advantages of high bandwidth, low loss, long transmission distance, strong interference resistance and the like, and gradually becomes a better transmission medium applied to a time-frequency synchronous network. However, the optical fiber link is particularly sensitive to external environment changes, and when the optical fiber link is affected by external temperature, mechanical disturbance and other factors, the optical path change of an optical signal transmitted in the optical fiber brings relatively large optical fiber delay (the temperature coefficient of the optical fiber delay is about 30 ps/c · km), and the optical fiber delay causes phase change of a transmitted frequency signal, so that the accuracy and stability of the transmitted frequency signal are degraded. Therefore, in order to improve the frequency synchronization accuracy based on the optical fiber network, it is necessary to monitor the phase change of the frequency signal generated during the transmission process of the optical fiber link in real time and compensate in time.
The traditional method is that a large dynamic range high-precision adjustable optical delay device is connected in series in a transmitted optical link, so that phase change caused by factors such as environment can be compensated. But the tunable optical delay line has large volume and slow compensation speed, which is not favorable for practical engineering application.
Therefore, the prior art has the following technical problems:
firstly, the optical path of an optical signal passing through an optical fiber is changed due to the fact that an optical fiber link is susceptible to environment, and therefore time delay change of frequency synchronization signals transmitted through the optical fiber is caused.
Secondly, because the time delay of the optical signal in the optical fiber link is related to the environmental change (especially the temperature) and the optical fiber length, when the temperature change is larger, the length of the optical fiber affected by the temperature is longer, the time delay change of the signal transmitted through the optical fiber is larger, and the time delay required to be compensated is larger, but the compensation range of the signal time delay compensation device is limited, and all the time delay compensation requirements cannot be met.
And thirdly, optical signals with different wavelengths are usually adopted in an optical fiber link to carry out bidirectional transmission to measure the time deviation between a master node and a slave node, but the time delay changes caused by the changes of environmental factors such as temperature and the like when the optical signals with different wavelengths are transmitted in the same optical fiber are different, so that the time delay of the bidirectional transmission signals of the optical signals with different wavelengths has asymmetry, and the asymmetry can bring adverse effects on the measurement precision of the time deviation between the master node and the slave node.
And fourthly, for multi-node frequency synchronization, the master node generally transmits frequency synchronization signals to each slave node through a transmission network formed by a plurality of nodes in series, and each slave node receives the frequency synchronization signals of the master node, so that all the slave nodes are kept synchronous with the master node, and the multi-node frequency synchronization is realized. However, the number of nodes passing through between the master node and the slave node affects the synchronization accuracy, and the more nodes pass through, the lower the synchronization accuracy.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a multi-node high-precision frequency synchronization method and system based on an optical fiber network, which are used for realizing multi-node high-precision frequency synchronization in the coverage range of the optical fiber network without an optical fiber amplifier.
On one hand, the invention is realized by the following technical scheme:
a multi-node high-precision frequency synchronization method based on an optical fiber network comprises the following steps:
step one, the main node equipment passes frequency signals with the wavelength of lambdaFIs continuously transmitted to the optical fiber network with the wavelength of lambdaFThe optical signals are transmitted to all slave nodes in the network through an optical fiber network;
step two, all slave node devices receive the information from the optical fiber network and have the slave wavelength lambdaFRecovering a first frequency signal from the optical signal;
step three, adopting wavelength lambda between master node equipment and slave node equipmentTThe optical signal of the optical network is subjected to half-duplex communication, and each time of communication, the slave node equipment at least needs to complete 1 time of time deviation measurement between the master node equipment and the slave node equipment;
and step four, the slave node equipment calculates a time delay compensation value according to the time deviation data measured each time, and the time delay compensation value is used for controlling the high-precision time delay compensator to carry out time delay compensation on the first frequency signal, so that the second frequency signal obtained after compensation and the frequency signal of the master node equipment keep high-precision synchronization.
Preferably, the master node device communicates with each slave node device by using a time division multiplexing mechanism.
Preferably, when the slave node device performs delay compensation on the first frequency signal by using the high-precision delay compensator, the dynamic compensation range of the high-precision delay compensator should be greater than 1 period value of the first frequency signal.
Preferably, the frequency of the first frequency signal is f, and the maximum delay variation value in each slave node device in the time interval Δ T is fΔDmaxThe master node device trains each slave node device in turn more frequently than the master node deviceTo ensure that the maximum delay variation of the first frequency signal received from each slave node device within the two rounds of training interval is less than 1 cycle of the first frequency.
Preferably, in the third step, the process of measuring the time offset between the master node device and the slave node device by the slave node device is as follows:
step 3.1, the master node equipment forms a Sync message by the characteristic data and the time data of the alternate training slave node equipment and sends the Sync message to an optical fiber network through an optical fiber port of the master equipment; the time of the master node equipment at the sending moment of the Sync message is T1, and T1 is sent together with the Sync message or temporarily cached;
step 3.2, each slave node device receives the Sync message sent by the master node device, identifies whether the Sync message is local data according to the characteristic data of the slave node device, and directly discards the Sync message if the Sync message is non-local data; if the Sync message is the local data, receiving the Sync message data, and recording the time of the Sync message reaching the local as T2;
step 3.3, after receiving the Sync message belonging to the local machine from the node equipment, immediately generating a Req message containing local machine characteristic data and sending the Req message to the optical fiber interface, and recording the sending time of the Req message as T3 by the slave node equipment;
step 3.4, the master node equipment receives and analyzes the Req message data, records the time of the receiving time of the Req message as T4, and then sends a Resp message to the slave node equipment which sends the Req message, wherein the Resp message comprises the characteristic data of the slave node equipment, T4 data and T1 data;
step 3.5, after receiving the Resp message belonging to the slave node device, the slave node device parses time data T4 and T1 in the Resp message, so that the slave node device collects all time data for calculating the time offset of the master node device and the slave node device, and then calculates the time offset data offset according to the time offset calculation formula between the master node device and the slave node device:
step 3.6, time deviation measurement between the master node equipment and the 1 slave node equipment is completed for 1 time, and time deviation measurement between the master equipment and the slave node equipment needs to be completed for at least 1 time when the master node equipment trains 1 slave node equipment in turn each time; and after the master node equipment completes communication with 1 slave node equipment, the master node equipment communicates with other slave node equipment according to the steps of 3.1-3.5.
Preferably, in the fourth step, the delay compensation value is calculated as follows:
step 4.1, when the master node equipment works stably and the slave node equipment normally receives the frequency signal of the master node equipment, setting the time delay compensation value to the middle value of the effective dynamic compensation range of the high-precision time delay compensator, finishing the 1 st measurement value by the slave node equipment, and if the 1 st measurement value is integral multiple of the period of the first frequency signal, directly taking the 1 st measurement value as the first measurement value; otherwise, the 1 st measurement value is used as a first measurement value after being an integral multiple of the first frequency signal period in a time delay compensation mode;
4.2 after the slave node device works stably, taking other measured values of the slave node device every time as second measured values except the first measured value, subtracting the first measured value from the second measured value to obtain a delay compensation value when the second measured value is obtained, and adding or subtracting a period value of a first frequency signal as the delay compensation value and acting on the high-precision delay compensator to finish 1 time of delay compensation if the delay compensation value plus the delay compensation value of the current high-precision delay compensator exceeds the effective dynamic compensation range of the delay compensator; if the time delay compensation value plus the time delay compensation value of the current high-precision time delay compensator is in the effective dynamic compensation range of the time delay compensator, the time delay compensation value is adopted to directly act on the time delay compensator to complete 1 time of time delay compensation.
On the other hand, in order to implement the high-precision frequency synchronization method, the invention further provides a multi-node high-precision frequency synchronization system based on the optical fiber network, the system at least comprises 1 master node device and more than 1 slave node device, and the master node device and the slave node devices are connected through the optical fiber network.
Preferably, the master node device includes a time core unit, a measurement control unit, a frequency transmission unit, and a wavelength division multiplexer; the frequency signals are respectively sent to a frequency transmission unit and a time core unit, and the time core unit provides real-time data of the main equipment for the measurement control unit; the passing wavelength of the measurement control unit is lambdaTCommunicate with each slave node; the frequency transfer unit modulates the frequency signal to a wavelength of lambdaFFor wavelength division multiplexer for converting the wavelength to lambdaTOptical signal of and wavelength of lambdaFMultiplexing or demultiplexing the optical signal.
Preferably, the slave node device includes a frequency receiving unit, a deviation measuring unit, a time core unit, a compensation calculating unit, a high-precision time delay compensator and a wavelength division multiplexer; the frequency receiving unit is used for receiving the wavelength lambdaFOf optical signal of wavelength lambdaTIs sent to a deviation measuring unit, the frequency receiving unit receives the optical signal with the wavelength of lambdaFThe optical signal of the optical network system recovers a first frequency signal, the first frequency signal is subjected to time delay compensation through a high-precision time delay compensator to obtain a second frequency signal, the second frequency signal drives the time of a time core running slave node equipment to provide real-time data of the slave node equipment for a deviation measurement unit, the deviation measurement unit realizes the measurement of time deviation between the master node equipment and the slave node equipment, a compensation calculation unit calculates a time delay compensation value according to the time deviation measured by the deviation measurement unit and is used for controlling the high-precision time delay compensator to perform time delay compensation on the first frequency signal, so that the compensated second frequency signal is kept in high-precision synchronization with the frequency signal of the master node equipment, and a wavelength division multiplexer is used for enabling the wavelength to be lambdaTOptical signal of and wavelength of lambdaFMultiplexing or demultiplexing the optical signal.
Preferably, the master node device communicates with each slave node through a time division multiplexing mechanism, and performs data frame interaction with the slave node in a half-duplex communication manner.
The invention has the following advantages and beneficial effects:
the invention adopts a tree-shaped optical fiber network structure for multi-node high-precision frequency synchronization, utilizes a time division multiplexing mechanism to realize the measurement of time deviation of the master node equipment and the slave node equipment, and realizes the compensation of receiving frequency signals of the slave node equipment through a time delay compensation algorithm so as to achieve the high-precision synchronization of the frequency signals with the master node equipment.
The invention adopts a point-to-point synchronous measurement mechanism, reduces intermediate node equipment and can effectively improve the measurement precision; the time division multiplexing mechanism is adopted to improve the efficiency of the main node equipment, reduce the hardware complexity of the main node and meet the application requirements of a multi-node high-precision frequency synchronization signal transmission network within the coverage range of an optical fiber network without an optical fiber amplifier
The invention adopts a same-wavelength bidirectional half-duplex time deviation measuring mechanism, can effectively improve the measuring precision of time deviation, further improves the compensation precision, and finally improves the frequency synchronization precision of the slave nodes.
The time delay compensation control method adopted by the invention can reduce the requirement on the effective dynamic range of the high-precision time delay compensation device, save the application cost, improve the performance and facilitate the application.
The invention makes full use of the characteristic that the frequency signal has periodicity, carries out time delay control within 1 time delay change period, ensures the effectiveness of time delay compensation, and reduces the requirement on the effective dynamic compensation range of the time delay compensation device.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic diagram of the system of the present invention.
FIG. 2 is a schematic diagram of the implementation of high-precision frequency synchronization between master and slave nodes according to the present invention.
Fig. 3 is a schematic diagram of a time division multiplexing measurement mechanism used in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Examples
As shown in fig. 1, the optical fiber network is a "tree" network composed of passive optical splitters and single optical fibers, and the network at least includes 1 master node and more than 1 slave node. The main process for realizing multi-node frequency synchronization is as follows:
1) the master node equipment passes the frequency signal through the frequency signal with the wavelength lambdaFIs continuously sent out to the optical fiber network with the wavelength of lambdaFThe optical signals are transmitted to all slave nodes in the network through an optical fiber network;
2) all slave nodes slave optical fiber links with the wavelength lambdaFRecovering a first frequency signal from the optical signal, wherein the first frequency signal is a second frequency signal after passing through a high-precision time delay device;
3) the wavelength is lambda between the master node equipment and the slave node equipmentTThe optical signal carries out bidirectional and semi-bidirectional communication, and each communication at least needs to complete 1 time of time deviation measurement between the master node equipment and the slave node equipment. The time delay asymmetry of a bidirectional transmission link can be effectively eliminated by adopting a same-wavelength half-duplex bidirectional comparison measurement mechanism, and the influence caused by environmental factors such as temperature is minimum, so that the aim of improving the time deviation measurement precision is fulfilled, and the high-precision frequency synchronization between the slave node and the master node equipment is finally realized;
4) the master node equipment communicates with each slave node equipment by adopting a time division multiplexing mechanism;
5) the slave node equipment adopts a high-precision time delay compensation device to control the time delay of the first frequency signal, and the dynamic compensation range of the high-precision time delay device is required to be larger than 1 period value of the first frequency signal;
6) the frequency of the first frequency signal is f, and the maximum time delay change value in each slave device is delta D in the time interval delta TmaxThe master node device trains each slave node in turn with a frequency greater than that of the master node deviceEnsuring that the maximum time delay variation of the first frequency signal received by each slave node device in the interval time of two rounds of training is less than 1 period of the first frequency signal;
7) the slave node equipment calculates a first frequency signal delay compensation value according to the time deviation data measured each time, and the calculation process is as follows:
a) when the master node equipment works stably and the slave node equipment normally receives the frequency signal of the master equipment, setting a time delay compensation value to a middle value of an effective dynamic compensation range of the high-precision time delay compensation device, wherein the slave node equipment finishes that the 1 st measured value is a first measured value which is an integral multiple value of a first frequency signal period, and if the integral multiple value of the first frequency signal period is not the integral multiple value of the first frequency signal period, the first measured value can be used as the first measured value only by adopting a time delay compensation mode;
b) after the slave equipment works stably, except the first measured value, the other measured values at each time are second measured values, when the second measured value is obtained, the second measured value is used for subtracting the first measured value to obtain a delay compensation value (with a symbol), if the delay compensation value plus the compensation value of the current delay compensator exceeds the effective dynamic compensation range of the delay compensator, the periodic value of the first frequency signal (the compensation value to be executed is in the effective dynamic compensation range of the delay compensator) is added or subtracted to serve as the compensation value to act on the delay compensator, and 1 time delay compensation is completed; if the time delay compensation value plus the compensation value of the current time delay compensator is in the effective dynamic compensation range of the time delay compensator, the value is directly calculated and acts on the time delay compensator to complete the time delay compensation for 1 time.
As shown in fig. 2, the master node device and the slave node device are connected via an optical fiber network, and the frequency synchronization signal is transmitted from the master node device to the slave node device, and the time deviation value between the frequency signal received by the slave node device and the frequency signal of the master node device is measured in real time by using the time deviation measurement method provided by the present invention, and then the slave node device calculates the time delay variation value of the frequency signal received by the slave node device according to the time deviation value, and performs time delay compensation on the received frequency signal by using a high-precision time delay compensation device, thereby finally realizing high-precision synchronization between the frequency signal of the slave node device and the frequency signal of the master node device.
The frequency signal input by the main node device from the outside of the device or the signal of the high stable frequency source in the device is respectively sent to the frequency transmission unit and the time core unit. The time core unit is driven by the frequency signal to operate the time of the main equipment and provide real-time data of the main equipment for the measuring unit; the frequency transfer unit modulates the frequency signal to a wavelength of lambdaFAnd transmitted to the optical fiber network. The measurement control unit utilizes the wavelength of lambda by a time division multiplexing mechanismTThe optical signals are communicated with each slave node, and data frame interaction is carried out between the optical signals and the slave nodes by adopting a same-wavelength bidirectional half-duplex mode, so that the time deviation between master node equipment and slave node equipment is measured with high precision. Wavelength division multiplexing device for realizing frequency transmission wavelength lambdaFOptical signal and measured data frame wavelength lambdaTThe function of multiplexing and demultiplexing optical signals.
The slave node device demultiplexes the wavelength lambda from the wavelength division multiplexerFThe optical signal is sent to a frequency receiving unit with a wavelength of lambdaTThe optical signals sent by the deviation measuring unit are multiplexed into a single optical fiber interface of the equipment and transmitted to an optical fiber network. Frequency receiving unit with wavelength of lambdaFThe first frequency signal is recovered from the optical signal, and the second frequency signal is obtained after the first frequency signal passes through the high-precision delayer. The second frequency signal drives the time of the time core running the slave node device, and provides real-time data of the slave node device for the deviation measuring unit. The offset side measuring unit has a wavelength λTThe data frame of the device is received and identified in the optical signal, and the high-precision measurement of the time deviation between the master node device and the slave node device is finally realized by carrying out data frame interaction with the master node device. The compensation calculation unit carries out stability monitoring between the second frequency signal and the main node equipment according to the collected time deviation data between the main node equipment and the slave node equipment, and calculates a time delay compensation value according to a monitoring result to control high-precision time delay compensationThe compensator performs time delay compensation on the first frequency signal, so that the compensated second frequency signal and the frequency signal of the main node equipment keep high-precision synchronization.
The implementation method for measuring the time offset between the master node device and the slave node device by using the time division multiplexing mechanism in this embodiment is as shown in fig. 3, where the master node device sequentially communicates with each slave node device by using the time division multiplexing mechanism, and each communication includes 3 messages, that is, a Sync message, a Req message, and a Resp message, where the Sync message and the Req message are used for performing bidirectional comparison between the master node device and the slave node device, and transmit time information of the Req message received by the master node device to the slave node device together with the Resp message, so that the slave node device collects all data for calculating the time offset of the master node device and the slave node device. The treatment process is as follows:
1) the master node equipment forms a Sync message by characteristic data such as equipment addresses of the polling slave node equipment and time data, and sends the Sync message to an optical fiber network through an optical fiber port of the master equipment. The time of the master node device at the sending time of the Sync message is T1, the data is sent together with the Sync message, or temporarily cached, and the Resp message is sent together.
2) Each slave node device receives a Sync message sent by the master node device, identifies whether the Sync message is local data according to characteristic data such as slave device addresses, and directly discards the Sync message if the Sync message is identified as non-local data; if the Sync message is the local data, the Sync message data is received, and the time of the Sync message reaching the local is recorded as T2.
3) After receiving the Sync message belonging to the local device from the node device, the slave node device immediately generates a Req message containing characteristic data such as the address of the local device and transmits the Req message to the optical fiber interface, and the slave node device records the transmission time of the Req message as T3.
4) The master node equipment receives and analyzes the Req message data, records the time of the receiving time of the Req message as T4, and then sends a Resp message to the slave node equipment which sends the Req message, wherein the message comprises characteristic data such as the equipment address of the slave node equipment, and T4 and T1 data.
5) After receiving the Resp message belonging to the slave node device, the slave node device analyzes the time data T4 and T1 in the Resp message, so that the slave node device collects all the time data for calculating the time offset of the master node device and the slave node device, namely T1, T2, T3 and T4, and then calculates the time offset data (offset) according to the time offset calculation formula between the slave node device and the master node device.
6) The master node device and the 1 slave node device complete 1 time of slave and master time deviation measurement, and each round of training 1 slave node device needs to complete at least 1 time of time deviation measurement. After the master node device completes communication with 1 slave node device, the master node device communicates with other slave node devices according to the steps 1) to 5).
After the slave node equipment and the master node equipment perform time deviation measurement each time, a time delay compensation value is calculated according to a time delay compensation algorithm and is used for controlling a high-precision time delay compensation device to realize compensation of a slave clock receiving frequency signal, and finally, high-precision synchronization of the slave node equipment and the master node equipment is realized.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. The multi-node high-precision frequency synchronization method based on the optical fiber network is characterized by comprising the following steps of:
step one, the main node equipment passes frequency signals with the wavelength of lambdaFIs continuously transmitted to the optical fiber network with the wavelength of lambdaFThe optical signals are transmitted to all slave nodes in the network through an optical fiber network;
step two, all slave node devices receive the information from the optical fiber network and have the slave wavelength lambdaFRecovers the first frequency from the optical signalA signal;
step three, adopting wavelength lambda between master node equipment and slave node equipmentTThe optical signal of the optical network is subjected to half-duplex communication, and each time of communication, the slave node equipment at least needs to complete 1 time of time deviation measurement between the master node equipment and the slave node equipment;
step four, the slave node equipment calculates a time delay compensation value according to the time deviation data measured each time, and the time delay compensation value is used for controlling the high-precision time delay compensator to carry out time delay compensation on the first frequency signal, so that the second frequency signal obtained after compensation and the frequency signal of the master node equipment keep high-precision synchronization; in the fourth step, the calculation process of the delay compensation value is as follows:
step 4.1, when the master node equipment works stably and the slave node equipment normally receives the frequency signal of the master node equipment, setting the time delay compensation value to the middle value of the effective dynamic compensation range of the high-precision time delay compensator, finishing the 1 st measurement value by the slave node equipment, and if the 1 st measurement value is integral multiple of the period of the first frequency signal, directly taking the 1 st measurement value as the first measurement value; otherwise, the 1 st measurement value is used as a first measurement value after being an integral multiple of the first frequency signal period in a time delay compensation mode;
4.2 after the slave node device works stably, taking other measured values of the slave node device every time as second measured values except the first measured value, subtracting the first measured value from the second measured value to obtain a delay compensation value when the second measured value is obtained, and adding or subtracting a period value of a first frequency signal as the delay compensation value and acting on the high-precision delay compensator to finish 1 time of delay compensation if the delay compensation value plus the delay compensation value of the current high-precision delay compensator exceeds the effective dynamic compensation range of the delay compensator; if the time delay compensation value plus the time delay compensation value of the current high-precision time delay compensator is in the effective dynamic compensation range of the time delay compensator, the time delay compensation value is adopted to directly act on the time delay compensator to complete 1 time of time delay compensation.
2. The method of claim 1, wherein the master node device communicates with each slave node device using a time division multiplexing scheme.
3. The method as claimed in claim 1, wherein the slave node device performs delay compensation on the first frequency signal by using the high-precision delay compensator, and the dynamic compensation range of the high-precision delay compensator is required to be greater than 1 period of the first frequency signal.
4. The method of claim 3, wherein the frequency of the first frequency signal is f, and the maximum delay variation value in each slave node device within the time interval Δ T is Δ DmaxThe master node device trains each slave node device in turn more frequently than the master node deviceTo ensure that the maximum delay variation of the first frequency signal received from each slave node device within the two rounds of training interval is less than 1 cycle of the first frequency.
5. The method for multi-node high-precision frequency synchronization based on the optical fiber network as claimed in claim 1, wherein in the third step, the slave node device measures the time offset between the master node device and the slave node device by the following procedure:
step 3.1, the master node equipment forms a Sync message by the characteristic data and the time data of the alternate training slave node equipment and sends the Sync message to an optical fiber network through an optical fiber port of the master equipment; the time of the master node equipment at the sending moment of the Sync message is T1, and the time is temporarily cached in T1;
step 3.2, each slave node device receives the Sync message sent by the master node device, identifies whether the Sync message is local data according to the characteristic data of the slave node device, and directly discards the Sync message if the Sync message is non-local data; if the Sync message is the local data, receiving the Sync message data, and recording the time of the Sync message reaching the local as T2;
step 3.3, after receiving the Sync message belonging to the local machine from the node equipment, immediately generating a Req message containing local machine characteristic data and sending the Req message to the optical fiber interface, and recording the sending time of the Req message as T3 by the slave node equipment;
step 3.4, the master node equipment receives and analyzes the Req message data, records the time of the receiving time of the Req message as T4, and then sends a Resp message to the slave node equipment which sends the Req message, wherein the Resp message comprises the characteristic data of the slave node equipment, T4 data and T1 data;
step 3.5, after receiving the Resp message belonging to the slave node device, the slave node device parses time data T4 and T1 in the Resp message, so that the slave node device collects all time data for calculating the time offset of the master node device and the slave node device, and then calculates the time offset data offset according to the time offset calculation formula between the master node device and the slave node device:
step 3.6, time deviation measurement between the master node equipment and the 1 slave node equipment is completed for 1 time, and time deviation measurement between the master equipment and the slave node equipment needs to be completed for at least 1 time when the master node equipment trains 1 slave node equipment in turn each time; and after the master node equipment completes communication with 1 slave node equipment, the master node equipment communicates with other slave node equipment according to the steps of 3.1-3.5.
6. A multi-node high-precision frequency synchronization system based on an optical fiber network, which is used for realizing the high-precision frequency synchronization method in any one of claims 1 to 5, and is characterized by comprising at least 1 master node device and more than 1 slave node device, wherein the master node device and the slave node devices are connected through the optical fiber network.
7. The multi-node high-precision frequency synchronization system based on the optical fiber network as claimed in claim 6, wherein the master node device comprises a time core unit, a measurement control unit, a frequency transmission unit and a wavelength division multiplexer; the frequency signals are respectively sent to the frequency transmission unitsThe time core unit provides real-time data of the main equipment for the measurement control unit; the passing wavelength of the measurement control unit is lambdaTCommunicate with each slave node; the frequency transmission unit modulates the frequency signal to the wavelength of lambdaFFor wavelength division multiplexer for converting the wavelength to lambdaTOptical signal of and wavelength of lambdaFMultiplexing or demultiplexing the optical signal.
8. The multi-node high-precision frequency synchronization system based on the optical fiber network as claimed in claim 6, wherein the slave node device comprises a frequency receiving unit, a deviation measuring unit, a time core unit, a compensation calculating unit, a high-precision delay compensator and a wavelength division multiplexer; the frequency receiving unit is used for receiving the wavelength lambdaFOf optical signal of wavelength lambdaTIs sent to a deviation measuring unit, the frequency receiving unit receives the optical signal with the wavelength of lambdaFThe optical signal of the optical network system recovers a first frequency signal, the first frequency signal is subjected to time delay compensation through a high-precision time delay compensator to obtain a second frequency signal, the second frequency signal drives the time of a time core running slave node equipment to provide real-time data of the slave node equipment for a deviation measurement unit, the deviation measurement unit realizes time deviation measurement between master node equipment and slave node equipment, a compensation calculation unit calculates a time delay compensation value according to the time deviation measured by the deviation measurement unit to control the high-precision time delay compensator to perform time delay compensation on the first frequency signal, so that the compensated second frequency signal is kept in high-precision synchronization with the frequency signal of the master node equipment, and a wavelength division multiplexer is used for enabling the wavelength to be lambdaTOptical signal of and wavelength of lambdaFMultiplexing or demultiplexing the optical signal.
9. The multi-node high-precision frequency synchronization system based on the optical fiber network as claimed in claim 6, wherein the master node device communicates with each slave node through a time division multiplexing mechanism and performs data frame interaction with the slave node by using a half-duplex communication method.
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| CN109981211B (en) * | 2019-03-21 | 2020-02-07 | 上海交通大学 | Distributed optical fiber time frequency joint transmission system and transmission method |
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| CN112187346B (en) * | 2020-09-18 | 2022-01-11 | 中国人民解放军海军工程大学 | Round-trip time delay difference estimation method for optical fiber time transmission under temperature change |
| CN112398531B (en) * | 2020-11-03 | 2021-12-10 | 中国科学院上海天文台 | Sagnac time delay correction method and system for optical fiber time-frequency transmission of dead path information |
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