CN108809469B - Time comparison synchronization algorithm suitable for radar pulse communication equipment networking - Google Patents
Time comparison synchronization algorithm suitable for radar pulse communication equipment networking Download PDFInfo
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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
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
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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
- H04J3/0602—Systems characterised by the synchronising information used
- H04J3/0605—Special codes used as synchronising signal
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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
- H04J3/0602—Systems characterised by the synchronising information used
- H04J3/0605—Special codes used as synchronising signal
- H04J3/0608—Detectors therefor, e.g. correlators, state machines
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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
Abstract
The invention discloses a time comparison synchronization algorithm suitable for networking of radar pulse communication equipment, wherein a radar module sends out a control signal M0; the master node and the slave node of the radar pulse communication equipment networking respectively receive a control signal M0 from respective radar modules; and performing point-to-point synchronous operation between the master node and the slave node, wherein the point-to-point synchronous operation process needs 3 communication time slots which are respectively a first time slot, a second time slot and a third time slot. The invention realizes the effect of high-precision time synchronization of the whole network in the formation networking mode.
Description
Technical Field
The invention relates to the technical field of radar pulse communication, in particular to a time comparison synchronization algorithm suitable for networking of radar pulse communication equipment.
Background
With the development of modern informatization war, a complex information network which can sense and detect battlefield environment anytime and anywhere and can perform high-speed stable data transmission needs to be constructed. Among them, both radar systems and communication systems play an extremely important role. In order to reduce the volume and power consumption of the equipment, the pulse communication equipment based on the radar is produced. The device transmits communication pulses at the interval of the radar transmission detection pulses, and realizes transmission at a longer distance and a higher speed than general communication devices by virtue of the advantages of high power of the radar device, directivity of an antenna and the like.
In the design of radar pulse communication equipment, the division of the time slots occupied by the communication pulses has a significant impact on the performance of the system. Considering the requirement of battlefield radar formation networking, time slots need to be dynamically divided for each device, so as to realize joint work. This requires that the devices work together at a uniform absolute time in a formation network of radar communication integrated devices. However, in fact, when each device is powered on, its local time is different, and therefore, it is first necessary to synchronize the devices (hereinafter referred to as "nodes") in the formation network. Although time synchronization of each node can be realized by adopting an external clock (such as a Beidou satellite system) time service strategy, the robustness of the system can be reduced by completely depending on external clock time service, and the breakdown of the whole network is easily caused under the condition that satellite signals are interfered or damaged. Therefore, the radar communication integrated equipment formation network must have the node self-synchronization capability, that is, all the nodes and the central node perform time synchronization, and finally, the clock unification of the whole network is achieved.
Currently, many researches are made on synchronization of radar networking, for example, the clock synchronization control method and device of the patent document "fanlinggang, chengzao, zhao, high-frequency ground wave radar networking" CN, CN101738600A [ P ]. 2010 "and the document" liu chen, chenxihong, liu qiang ", etc. a new method for bistatic radar time synchronization [ J ]. electro-optical and control, 2014, 21(4):10-14. However, the time slot division of the radar pulse and the communication pulse of each user is needed in the formation and networking of the radar pulse communication equipment, so that the radar module and the communication module work cooperatively, the synchronization process is more complex, and no research on the time synchronization algorithm of the formation and networking of the radar pulse communication equipment exists at present.
Disclosure of Invention
The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art, and to provide a time comparison synchronization algorithm suitable for networking of radar pulse communication devices.
In order to solve the technical problems, the invention provides a time comparison synchronization algorithm suitable for formation networking of radar pulse communication equipment, and the time comparison synchronization algorithm is used for realizing the high-precision time synchronization effect of the whole network in a formation networking mode.
The technical scheme of the invention is as follows:
the time comparison synchronization algorithm is suitable for networking of radar pulse communication equipment,
the radar module sends out a control signal M0;
the master node and the slave node of the radar pulse communication equipment networking respectively receive a control signal M0 from respective radar modules;
the point-to-point synchronous operation between the master node and the slave node, wherein the point-to-point synchronous operation process needs 3 communication time slots, namely a first time slot, a second time slot and a third time slot, and the specific implementation mode comprises the following steps:
the method comprises the following steps: the master node sends a handshake packet CT1 in a first time slot when receiving a control signal M0, the master node starts a first Timer1 to start timing and monitor signals while sending a handshake packet CT1, waits for receiving the handshake packet CT2, the handshake packet CT1 reaches a slave node after a path propagation delay delta T, the slave node continuously monitors a channel all the time, waits for receiving a handshake packet CT1, decodes immediately after successfully receiving the handshake packet CT1, starts a second Timer2 to start timing at the moment when a correlation peak in the handshake packet CT1 is detected, waits for the control signal M0, the time from the time when the handshake packet CT1 signal reaches the slave node to the time when the slave node detects the correlation peak in the handshake packet CT1 is T1, and the T1 is a fixed known quantity;
step two: after the slave node successfully receives the handshake packet CT1 packet in the first time slot, the slave node continues to wait until the control signal M0 is received in the second time slot, the slave node starts to transmit the handshake packet CT2, the handshake packet CT2 includes a time T2 from the beginning of counting by the second Timer2 to the beginning of transmitting the handshake packet CT2, the master node detects a correlation peak in the second time slot, the master node decodes the handshake packet CT2 packet to obtain a time T2 from the beginning of counting by the second Timer2 transmitted by the slave node to the beginning of transmitting the handshake packet CT2, the master node counts the total time T according to the time T2 from the beginning of counting by the second Timer2 to the beginning of transmitting the handshake packet CT2 included in the handshake packet CT2 and the first Timer1 when receiving the handshake packet CT2, calculates the path propagation delay Δ T, and the calculation formula is as follows: t = Δ T + T1+ T2+ Δ T + T1, resulting in a path propagation delay Δ T = (T-2 × T1-T2)/2;
step three: after the master node successfully receives the handshake packet CT2 in the second Time slot and calculates the path propagation delay Δ T, the master node continues to wait until the control signal M0 is received again and then transmits the handshake packet CT3, the handshake packet CT3 includes the master node absolute Time and the path propagation delay Δ T at the current transmission start Time, the slave node monitors the signal in the third Time slot, waits for receiving the handshake packet CT3, and after the handshake packet CT3 is successfully received, reads the path propagation delay Δ T in the handshake packet CT3 and the absolute Time of the master node at the current Time by decoding, the slave node detects a correlation peak in the third Time slot and starts to Time until the whole data packet reception is completed at T3, and when the whole data packet reception is completed, the current system Time of the whole network is the absolute Time, the path propagation delay Δ T, the handshake packet CT1 signal reaches the Time T1, the Time from the slave node to the Time when the slave node detects the correlation peak in the handshake packet CT1, The sum of the time t3 from when the node detects the correlation peak in the third time slot until the entire packet reception is completed.
Preferably, there are 1 master node and a plurality of slave nodes.
Preferably, the master node and the slave node are independent of each other in terms of the control signal M0 received from their respective radar modules.
Preferably, the unsynchronized slave node fails to successfully receive the handshake packet CT3 in the third time slot and continues to return to the listening channel state.
Preferably, the method further comprises that the synchronized slave node fails to successfully receive the handshake packet CT3 for 3 times in the third time slot and becomes an unsynchronized slave node.
Preferably, the method also comprises a synchronous calibration method, the frequency of the clock calibration is determined by the algorithm maximum error Te1, the clock stability Te2 and the maximum allowable error Te of the formation networking system, the time interval Tx of the clock calibration satisfies Te1+ Tx Te2< Te, namely Tx < (Te-Te1)/Te2, and the clock stability Te2 is the maximum deviation time of clocks of different nodes per second.
Preferably, the time alignment synchronization algorithm suitable for the networking of the radar pulse communication equipment further comprises a training sequence frame structure corresponding to the time alignment synchronization algorithm suitable for the networking of the radar pulse communication equipment, wherein the training sequence frame structure comprises a leader sequence, a frame header and a frame body.
Preferably, the frame body includes synchronization information, valid data and a unique word UW, the length of the unique word UW is 32 symbols, the length of the valid data is 960 symbols, the synchronization information is divided into 4 segments, each segment of 32 symbols adopts QPSK modulation, each symbol includes 2 bits of information, total 256 bits are used for transmitting time synchronization information, total 15 bytes of time synchronization information original information are added, a 1-byte check code is added, and RS (32, 16) encoding is adopted.
Preferably, the master node and the slave node each need 116-bit information transmission, add a check bit of 12 bits after the 116-bit information, and encode the check bit with the information of 128 bits, where the encoding is RS (32, 16) encoding, and the byte length m = 8.
Preferably, the point-to-point time synchronization error is less than 50ns, the convergence time is less than 10 communication pulse time slots, and the clock synchronization operation interval is greater than 1 s.
The invention achieves the following beneficial effects:
the invention is suitable for formation networking of radar pulse communication and can quickly realize time comparison synchronization. The algorithm realizes the cooperative work of the radar module and the communication module through the control signal M0, so that the whole network has accurate self-synchronization capability, the dependence of radar formation networking on external time service is reduced, and the robustness of the system is improved. The algorithm is suitable for a centralized formation network, is provided with a central node and a plurality of common nodes, and realizes the time synchronization of the whole network by synchronizing each node to the central node. The algorithm provides a frame structure design scheme, synchronous information is contained in communication pulses, and a certain noise and interference resistance is realized by using a strong error correcting code. For the newly accessed unsynchronized nodes, the algorithm adopts two handshakes to realize the accurate time synchronization between the master node and the slave node; for the synchronized nodes in the network, time synchronization tracking is carried out at regular intervals, thereby realizing stable synchronization. Actual measurement shows that the algorithm can ensure that the synchronization error between the nodes is less than 50 ns; the convergence time is less than 10 communication burst slots; the method has good support for the mobility of the nodes, and can realize stable synchronization under the condition that the moving speed of the nodes is lower than 60 km/h. The invention solves the problem of network self-synchronization in the formation networking scene of the radar pulse communication equipment. Has wide application potential in the fields of battlefield integrated information systems and the like.
Drawings
Fig. 1 is a schematic diagram of a formation networking system of radar pulse communication equipment.
Fig. 2 is a schematic diagram of a time slot flow in a synchronization process of a pair of master nodes and a slave nodes according to the present invention.
FIG. 3 is a flow chart illustrating a first step of the present invention.
FIG. 4 is a schematic flow diagram of steps one and two of the present invention.
FIG. 5 is a schematic flow chart of the first step, the second step and the third step of the present invention.
Fig. 6 is a schematic diagram of the frame structure of the present invention.
FIG. 7 is a diagram illustrating the allocation and encoding of synchronization information according to the present invention.
FIG. 8 is a schematic diagram of the testing process of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
Example 1
As shown in fig. 1, the present invention abstracts a radar communication integrated formation network into a network formed by a central node (master node) and a plurality of common nodes (slave nodes), so as to implement a synchronization process between the central node and each common node. The synchronization process between the central node and each common node can be decomposed into point-to-point time synchronization operations between 1 master node and 1 slave node. And after a time comparison synchronization algorithm, each node outputs a synchronization pulse, and corrects the local time of the slave node according to the time of the master node. Eventually all slave nodes synchronize the local time to the master node time.
By receiving the synchronization command control signal M0 sent by the radar module, the synchronization information is included in the data pulse frame, so that the devices simultaneously complete the time comparison and synchronization function between the devices in the process of completing the transmission and reception of the pulse data. The time comparison synchronous information and the service data are transmitted simultaneously, the synchronous information occupies not more than 32 bytes in each time slot, a modulation mode with strong noise resistance is adopted, and a strong error detection and correction mechanism is adopted to ensure the reliability.
The algorithm can achieve the following indexes:
1) the error of point-to-point time synchronization is less than 50 ns;
2) after synchronization is finished, continuous time error tracking can be carried out, deviation caused by clock drift among nodes is prevented, the nodes are always in a time synchronization state, and the clock synchronization operation interval is larger than 1 s;
3) the convergence state can be reached after 10 consecutive pulse time slots;
4) supporting node moving scene, node moving speed: < =60 km/h;
1. time comparison synchronization
The central node (master node) in the network should be manually selected when the network starts to work, and the rest nodes should be set as ordinary nodes (slave nodes). The time synchronization process of each common node is not interfered with each other, so that the synchronization behavior of the nodes can be simplified into the point-to-point synchronization behavior of a master node and a slave node.
The master node and the slave nodes receive the control of a synchronization command control signal M0 sent by the radar module, and transmit a synchronization pulse when receiving a control signal M0. The master node and the slave node respectively receive the control signal M0 from the respective radar modules, so the control signals M0 received by the master node and the slave node are independent of each other, and the triggering position of the control signal M0 needs to include a certain design to satisfy the function of eliminating interference between the receiving and the sending.
As shown in fig. 2, a synchronization process requires three communication time slots, namely a first time slot, a second time slot and a third time slot, the master node is used as a time reference in the network, and the node will perform the corresponding synchronization process according to its local time and the control signal M0. When the control signal M0 comes, the master node is in its communication time slot, sending a synchronization pulse, starting the synchronization process. The slave node will continue to listen to the channel before synchronizing. For the newly accessed slave nodes, when the synchronization pulse transmitted by the master node is monitored, the synchronization pulse is tried to be transmitted back to the master node for time synchronization; and for the synchronized slave nodes, time calibration is carried out by using the synchronization pulse and taking the master node as a reference. The process of synchronization is described in detail below:
the method comprises the following steps: as shown in fig. 3, the master node transmits the handshake packet CT1 in the first time slot upon receiving the control signal M0 trigger signal. While sending CT1, the master node starts Timer1 and listens to the channel, waiting to receive handshake packet CT 2. The handshake packet CT1 arrives at the slave node after a path propagation delay Δ T. The slave node continues to listen to the channel waiting for receipt of the handshake packet CT 1. If the CT1 is successfully received, decoding is immediately performed, a Timer2 is started at the time when the correlation peak in the CT1 is detected, the arrival of the control signal M0 is waited, Δ T is the path propagation delay required to be solved for synchronization, and T1 is the time from the arrival of the signal at the node CT1 to the detection of the correlation peak of the training sequence in the CT1 from the node. t1 is determined by the frame structure and front-end processing delay, and is a fixed known quantity;
step two: as shown in fig. 4, after the slave node successfully receives the CT1 packet in the time slot 1, the slave node waits until the control signal M0 of the own device is received in the time slot 2, and starts to transmit the handshake packet CT2, where the CT2 includes a time t2 from the Timer2 to the time when the CT2 starts to transmit.
If the master node detects the correlation peak in slot 2, i.e. the master node successfully receives the CT2, it indicates that there is a slave node that received the CT1 sent by the master node in slot 1 and replied to CT 2. The master node decodes the CT2 packet to obtain the time T2 from the Timer2 Timer transmitted by the slave node to the time when the CT2 starts to transmit, and the master node calculates the one-way propagation delay delta T between the node and the neighbor of the reply CT2 according to the total time T counted by the Timer1 Timer when the T2 and the CT2 are received.
The calculation formula is as follows:
obtaining:
step three: as shown in fig. 5, after successfully receiving the handshake packet CT2 in time slot 2 and calculating the propagation delay Δ T, the master node waits until it receives the control signal M0 again and then sends the handshake packet CT 3. The CT3 includes the absolute time of the master node at the current transmission start time and the path propagation delay Δ T. The slave node listens to the channel in slot 3 waiting to receive the handshake packet CT 3. If the handshake packet CT3 is successfully received, the single-line propagation delay Δ T in the CT3 and the absolute Time of the master node at the current Time are read by decoding. Meanwhile, the slave node starts timing when detecting the correlation peak until the Time when the whole packet reception is completed is T3, and when the whole packet reception is completed, the current system Time of the whole network = the master node absolute Time + the path propagation delay Δ T + T1+ T3.
For the unsynchronized slave nodes, the local time of the slave nodes is adjusted according to the current system time of the whole network, so that the time service operation of the master node on the slave nodes is completed. If the unsynchronized node fails to successfully receive the CT3 in slot 3, it continues back to the listening channel state. For synchronized slave nodes, the Δ T extracted from the packet will be used to correct the slave node's local slot partitioning. If the synchronized slave node fails to successfully receive CT 33 consecutive times in slot 3, its role becomes the unsynchronized slave node.
The master node counts time when the transmission time starts, outputs a synchronization pulse after T1+ delta T time, and the slave node outputs the synchronization pulse when detecting a correlation peak. The synchronous pulse signals output by the master node and the slave node are completely synchronous in time.
At this point, a time comparison synchronization process between the master node and the slave node is completed.
2. Post-synchronization clock calibration and tracking
When the slave nodes complete the synchronization, we can determine that any slave node has completed the synchronization at the absolute time and the time frame starting position, and the synchronized slave nodes can work normally in the system. However, after a period of time, the time error between the master node and the slave node becomes larger and larger due to the cumulative effect of the slight difference between the clock periods of the master node and the slave node, and therefore, the clock of the slave node needs to be periodically calibrated by the synchronous calibration method. The frequency of the clock calibration is determined by the algorithm maximum error Te1, the clock stability (namely the maximum deviation time of clocks of different nodes per second) Te2 and the maximum allowable error Te of the formation networking system, the time interval Tx of the clock calibration should be satisfied,
Te1+Tx*Te2<Te
namely, Tx < (Te-Te1)/Te2
In practical operation, the time interval of clock calibration may be slightly less than Tx, so as to ensure stable synchronous operation of the system.
3. Frame structure design
In order to meet the requirement of beyond-the-horizon communication of radar pulse communication equipment, the frame structure design needs to give an important consideration to resisting inter-code crosstalk caused by multipath. The invention adopts a frame structure containing a training sequence, as shown in fig. 6, the frame structure is a frame structure schematic diagram and the symbol number of each part, and the Automatic Gain Control (AGC), coarse frame synchronization, coarse carrier frequency offset estimation, fine frame synchronization, optimal sampling point determination, fine carrier frequency offset estimation, signal-to-noise ratio estimation and channel estimation are completed together. The preamble length is 330 symbols, the header 342 symbols, the unique word UW is 32 symbols, and the effective data length is 960 symbols. The synchronization information is divided into 4 segments, each segment has 32 symbols, and QPSK modulation is adopted, each symbol contains 2 bits of information, and 256 bits (32 bytes) are used for transmitting the time synchronization information. The time synchronization information is original information with 15 bytes, firstly, a check code with 1 byte is added, and then RS (32, 16) coding is adopted to ensure the correctness of the time synchronization information.
The bit allocation and coding scheme for the time synchronization information part, as shown in fig. 7, is 116 bits long for the time synchronization ratio information bits followed by 12 bits of check bits. The 128-bit information plus check bit is an information segment, and RS (32, 16) encoding is performed on the 128-bit information plus check bit, the byte length m =8, and the extension is 256 bits. And finally, dispersing the coded data in four data blocks of a frame structure, and carrying out interleaving coding. There is also a 128 bit supervision block.
The 116-bit time synchronization alignment information includes: an 8-bit node ID, an 8-bit sync pulse ID, a 70-bit system absolute Time, a 30-bit path propagation delay Δ T (master node) or a 30-bit transmission latency T2 (slave node). The system absolute Time includes year, month, day, hour, minute, millisecond, microsecond, nanosecond information, and each Time information occupies information bit number, as shown in table 1, which occupies 70 bits in total. The path propagation delay Δ T includes millisecond, microsecond, nanosecond information, and each time information occupies information bit number, as shown in table 2, which occupies 30 bits in total. The number of information bits occupied by the time information t2 transmitted from the node is 30 bits as shown in table 3.
TABLE 1 System Absolute Time Time occupancy information bit Allocation
| System absolute time | Year of year | Moon cake | Day(s) | Time of flight | Is divided into | Second of | Millisecond (ms) | Microsecond range | Nanosecond |
| Number of bits | 14 | 4 | 5 | 5 | 6 | 6 | 10 | 10 | 10 |
Table 2 path propagation delay deltat occupancy information bit allocation
| Path propagation delay | Millisecond (ms) | Microsecond range | Nanosecond |
| Number of bits | 10 | 10 | 10 |
Table 3 time information t2 transmitted from a node occupies information bit allocation
| Transmission wait time t2 | Millisecond (ms) | Microsecond range | Nanosecond |
| Number of bits | 10 | 10 | 10 |
4. Simulation experiment
Based on the time comparison synchronization algorithm provided by the invention, the networking synchronization of a prototype of the radar pulse communication equipment is actually measured, and the invention is further verified and explained by the actual measurement result.
FIG. 8 is a schematic diagram of the testing process of the present invention. Cable 1 and cable 2 will be selected to be long cables (greater than 30 meters) taking into account the distance relationship between the master and slave devices. The spectrometer is used to display the spectral characteristics of the input signal and the reference clock is used to observe time. When starting the test, the control computer 1 and the control computer 2 set respective parameters of the master node device and the slave node device, respectively. Test items and results were as follows:
(1) synchronous precision testing
The control signal generator generates a synchronization instruction control signal M0; and (4) observing whether the oscilloscope has the synchronous signal 1 and the oscilloscope has the synchronous signal 2 or not, and measuring the time difference between the oscilloscope and the oscilloscope. In actual measurement, the difference of the synchronous signals measured by the oscilloscope does not exceed 50 ns.
(2) Synchronous convergence time testing
The control signal generator generates a synchronization command control signal M0, sends two synchronization command control signals M0 to the master device, and sends two synchronization command control signals M0 to the slave device; and (4) observing whether the oscilloscope has the synchronous signal 1 and the synchronous signal 2 or not, and observing the number of the synchronous instruction control signals M0. In actual measurement, 4 control signals are needed to complete one synchronization, i.e. the algorithm completes synchronization in consecutive pulse time slots within 10.
(3) Synchronous trace testing
The control signal generator generates a control signal M0; and (5) observing whether the oscilloscope always has the synchronous signal 1 and the synchronous signal 2, and observing for 5 minutes. In actual measurement, the synchronizing signal can be observed on the oscilloscope all the time, and the difference does not exceed 50 ns. Namely, the algorithm can stably realize synchronous tracking.
(4) Time synchronized operation interval testing
The control signal generator generates a control signal M0 and the software interface sets the synchronization interval 1 s.
And (3) observing the synchronous signal 1 and the synchronous signal 2 on the oscilloscope, and measuring the time difference between the two signals for multiple times. In actual measurement, the difference of the synchronous signals measured by the oscilloscope for many times does not exceed 50ns, namely the algorithm can realize stable synchronization under the condition that the synchronization interval is 1 s.
(5) Node movement speed testing
Considering the difficulty of master and slave node movement under laboratory conditions, an alternative test method is adopted in the test. The problem with node movement is that the paths travel different distances in different time slots, so the environment of node movement is simulated by using the difference in length of cable 1 and cable 2 during testing. The maximum moving distance of the nodes in the two time slots is 0.167 m, so that the selected cable 1 is 50 m, and the selected cable 2 is 50.167 m.
After the control signal generator generates a control signal M0, the synchronizing signal 1 and the synchronizing signal 2 on the oscilloscope are observed, and the time difference between the two signals is measured. In actual measurement, the difference of the measurement synchronous signals of the oscilloscope does not exceed 50ns, which shows that the algorithm can ensure that stable time synchronization is realized when the moving speed of the node is not more than 60 km/h.
(6) Time synchronization information testing
The control computer is set to a data transmission mode, and noise is added by the noise source until an error code appears in the PN23 code sent by the control computer. Subsequently, the control computer is set to the synchronization mode, and the control signal generator generates a control signal M0; and observing a synchronous signal 1 and a synchronous signal 2 on the oscilloscope, and measuring the time difference between the two signals. In actual measurement, the difference of the synchronous signals measured by the oscilloscope does not exceed 50ns, which shows that the algorithm can ensure certain anti-noise capability by carrying out error correction coding on the time synchronous signals. The correctness, the effectiveness and the reliability of the invention are verified by experiments.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A time comparison synchronization algorithm suitable for networking of radar pulse communication equipment is characterized in that:
the radar module sends out a control signal M0;
the master node and the slave node of the radar pulse communication equipment networking respectively receive a control signal M0 from respective radar modules;
the point-to-point synchronous operation between the master node and the slave node, wherein the point-to-point synchronous operation process needs 3 communication time slots, namely a first time slot, a second time slot and a third time slot, and the specific implementation mode comprises the following steps:
the method comprises the following steps: the master node sends a handshake packet CT1 in a first time slot when receiving a control signal M0, the master node starts a first Timer1 to start timing and monitor signals while sending a handshake packet CT1, waits for receiving the handshake packet CT2, the handshake packet CT1 reaches a slave node after a path propagation delay delta T, the slave node continuously monitors a channel all the time, waits for receiving a handshake packet CT1, decodes immediately after successfully receiving the handshake packet CT1, starts a second Timer2 to start timing at the moment when a correlation peak in the handshake packet CT1 is detected, waits for the control signal M0, the time from the time when the handshake packet CT1 signal reaches the slave node to the time when the slave node detects the correlation peak in the handshake packet CT1 is T1, and the T1 is a fixed known quantity;
step two: after the slave node successfully receives the handshake packet CT1 packet in the first time slot, the slave node continues to wait until the control signal M0 is received in the second time slot, the slave node starts to transmit the handshake packet CT2, the handshake packet CT2 includes a time T2 from the beginning of counting by the second Timer2 to the beginning of transmitting the handshake packet CT2, the master node detects a correlation peak in the second time slot, the master node decodes the handshake packet CT2 packet to obtain a time T2 from the beginning of counting by the second Timer2 transmitted by the slave node to the beginning of transmitting the handshake packet CT2, the master node counts the total time T according to the time T2 from the beginning of counting by the second Timer2 to the beginning of transmitting the handshake packet CT2 included in the handshake packet CT2 and the first Timer1 when receiving the handshake packet CT2, calculates the path propagation delay Δ T, and the calculation formula is as follows: t = Δ T + T1+ T2+ Δ T + T1, resulting in a path propagation delay Δ T = (T-2 × T1-T2)/2;
step three: after the master node successfully receives the handshake packet CT2 in the second Time slot and calculates the path propagation delay Δ T, the master node continues to wait until the control signal M0 is received again and then transmits the handshake packet CT3, the handshake packet CT3 includes the master node absolute Time and the path propagation delay Δ T at the current transmission start Time, the slave node monitors the signal in the third Time slot, waits for receiving the handshake packet CT3, and after the handshake packet CT3 is successfully received, reads the path propagation delay Δ T in the handshake packet CT3 and the absolute Time of the master node at the current Time by decoding, the slave node detects a correlation peak in the third Time slot and starts to Time until the whole data packet reception is completed at T3, and when the whole data packet reception is completed, the current system Time of the whole network is the absolute Time, the path propagation delay Δ T, the handshake packet CT1 signal reaches the Time T1, the Time from the slave node to the Time when the slave node detects the correlation peak in the handshake packet CT1, The sum of the time t3 from when the node detects the correlation peak in the third time slot until the entire packet reception is completed.
2. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: the number of the main nodes is 1, and the number of the slave nodes is multiple.
3. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: the master node and the slave node are independent of each other in terms of the control signal M0 received from their respective radar modules.
4. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: the unsynchronized slave node fails to successfully receive the handshake packet CT3 in the third time slot and continues back to the listening channel state.
5. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: further comprising the step of changing the synchronized slave node to the unsynchronized slave node if the synchronized slave node fails to receive the handshake packet CT3 for 3 consecutive times in the third time slot.
6. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: the method also comprises a synchronous calibration method, wherein the synchronous calibration method is to perform clock calibration periodically through the point-to-point synchronous operation, the frequency of the clock calibration is determined by the maximum error Te1 of the algorithm, the clock stability Te2 and the maximum allowable error Te of the formation networking system, the time interval Tx of the clock calibration meets Te1+ Tx Te2< Te, namely Tx < (Te-Te1)/Te2, and the clock stability Te2 is the maximum deviation time per second of the clocks of different nodes.
7. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: the time comparison synchronization algorithm suitable for the networking of the radar pulse communication equipment also comprises a training sequence frame structure corresponding to the time comparison synchronization algorithm suitable for the networking of the radar pulse communication equipment, wherein the training sequence frame structure comprises a leader sequence, a frame head and a frame body.
8. The time alignment synchronization algorithm for radar pulse communication device networking of claim 7, wherein: the frame body comprises synchronous information, effective data and a unique word UW, the length of the unique word UW is 32 symbols, the length of the effective data is 960 symbols, the synchronous information is divided into 4 sections, each section of 32 symbols adopts QPSK modulation, each symbol comprises 2-bit information, 256 bits are used for transmitting time synchronous information, the total amount of time synchronous information is 15 bytes, 1-byte check codes are added, and RS32 or RS16 codes are adopted.
9. The time alignment synchronization algorithm for radar pulse communication device networking of claim 8 wherein: the main node and the slave nodes respectively need 116-bit information transmission, a 12-bit check bit is added after the 116-bit information, then the 128-bit information plus the check bit is coded, the coding adopts RS32 or RS16 coding, and the byte length m = 8.
10. The time alignment synchronization algorithm for radar pulse communication device networking of claim 1, wherein: the method also comprises that the point-to-point time synchronization error is less than 50ns, the convergence time is less than 10 communication pulse time slots, and the clock synchronization operation interval is more than 1 s.
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