CN110460404B - Time synchronization method suitable for time division multiplexing carrier transmission system bus - Google Patents
Time synchronization method suitable for time division multiplexing carrier transmission system bus Download PDFInfo
- Publication number
- CN110460404B CN110460404B CN201910722852.4A CN201910722852A CN110460404B CN 110460404 B CN110460404 B CN 110460404B CN 201910722852 A CN201910722852 A CN 201910722852A CN 110460404 B CN110460404 B CN 110460404B
- Authority
- CN
- China
- Prior art keywords
- time
- synchronization
- master node
- signal
- node
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
Abstract
The invention discloses a time synchronization method suitable for a time division multiplexing carrier transmission system bus, which comprises the steps that a slave node acquires a synchronization signal sent by a master node at fixed time, and the local time set of the arrival time of the synchronization signal is corrected through the arrival time of the synchronization signal and a time compensation quantity of propagation delay to form a closed loop method for self-updating of the synchronization time of the slave node. The invention overcomes the problem that the carrier transmission system in the prior art is difficult to establish time synchronization, and improves the accuracy of the synchronization time of the slave nodes in operation.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a time synchronization method suitable for a time division multiplexing carrier transmission system bus.
Background
The bus communication is information transmission by using a wired cable as a physical transmission medium, and has the advantages of simple system layout, reliable information transmission, low system cost and the like.
The hardware of the bus system consists of a physical transmission medium and several communication nodes. The former generally consists of a set of cables and mating connectors. Multiple communication nodes share the same transmission medium, and therefore, time division multiplexing is often used, that is, at most only one node transmits a signal at any one time. The division of time with centralized control requires the establishment of system-wide time synchronization, and therefore the time synchronization technique is one of the core techniques of the bus system.
By time synchronization is meant that all or some of the nodes in the bus network have the same time reference or that the nodes can convert each other's time to local time. The purpose of time synchronization is to maintain a globally consistent physical or logical clock so that information, events and time-related behaviors of nodes in the system have a globally consistent interpretation, and to ensure that data sent and received by the nodes are logically consistent in time. High accuracy time synchronization is the basis for proper operation of time division multiplexed bus systems.
The bus generally uses baseband transmission, i.e. mapping the bit sequence to logic levels (or level difference) and transmitting it directly on the physical medium, and the logic levels are limited. For example, in the RS232 standard, a level of-3 to-15 volts on TxD and RxD signal lines corresponds to a logic 1, and a level of +3 to +15 volts corresponds to a bit of 0. For another example, in the CAN bus, the level difference between the signal lines CAN _ H and CAN _ L is 2 volts corresponding to bit 0, and the level difference is 0 volts corresponding to bit 1.
Buses for baseband transmission are relatively easy to time synchronize according to the abrupt nature of the levels.
In order to improve the performances of throughput rate, bit error rate/block error rate and the like, some buses adopt a carrier transmission system. Different from baseband transmission, carrier transmission modulates bit sequences to be transmitted, modulated level waveforms are generally smooth and continuous, and bit error/packet error performance better than that of baseband transmission can be obtained under the same signal-to-noise ratio, so that the device can work in a severe environment with a lower signal-to-noise ratio, and the bus transmission distance can be greatly improved.
However, the above-mentioned benefits of the carrier transmission system are accompanied by a problem that the level waveform of the carrier transmission is smooth and continuous, and often works in a harsh environment with a low signal-to-noise ratio, it is difficult to establish time synchronization, and because the transmission distance is extended, the influence of the delay caused by the transmission of electromagnetic waves in the cable on the time synchronization cannot be ignored like a baseband transmission bus.
Disclosure of Invention
In order to solve the above technical problem, the present invention provides a time synchronization method suitable for a time division multiplexing carrier transmission system bus. In the method, the problem that the carrier transmission system in the prior art is difficult to establish time synchronization is solved, and the accuracy of the synchronization time of the slave nodes during operation is improved.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a time synchronization method suitable for a time division multiplexing carrier transmission system bus is characterized in that a slave node acquires a synchronization signal sent by a master node at fixed time, and a set of local time of the current time of the synchronization signal is corrected through local time corresponding to the arrival time of the synchronization signal and a propagation delay time compensation amount to form a closed-loop method for self-updating of the synchronization time of the slave node.
Preferably, the synchronization signal is an OFDM signal.
Preferably, the obtaining of the time compensation amount of the propagation delay includes the following steps:
the slave node sends a signal to the master node according to the distributed gap to acquire the arrival of the signal
Local time of the master node's time;
comparing the local time of the time of reaching the master node with the global time corresponding to the gap
Obtaining an error value;
feeding back the error value to the slave node, the slave node modifying the slave node according to the error value
The amount of time compensation.
Preferably, the local time of the time when the signal arrives at the master node is obtained by the master node measuring a pilot signal.
Based on the technical scheme, the invention has the beneficial effects that: the pseudo synchronization time is corrected by the slave nodes according to the difference between the time when the signals reach the master node and the global time corresponding to the gaps, the corrected slave nodes are the synchronization time with high accuracy, and the influence of delay brought by a carrier transmission system to be transmitted on time synchronization is reduced, so that the synchronization time of the slave nodes is approximately consistent with the synchronization time of the master node. The problem that time synchronization is difficult to establish in a carrier transmission system in the prior art is solved, and the accuracy of the synchronization time of the slave nodes in operation is improved.
Drawings
FIG. 1: the invention relates to a time synchronization method for a time division multiplexing carrier transmission system bus.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Example one
As shown in fig. 1, a time synchronization method suitable for a time division multiplexing carrier transmission system bus includes acquiring a synchronization signal sent by a master node at a fixed time from a slave node, and correcting a set of local times of the synchronization signal at a current time by using a local time corresponding to an arrival time of the synchronization signal and a time compensation amount of propagation delay to form a closed-loop method for self-updating of synchronization time of the slave node.
Further, the synchronization signal is an OFDM signal.
Further, obtaining a time compensation amount of the propagation delay includes the following steps:
the slave node sends a signal to the master node according to the distributed gap to acquire the arrival of the signal
Local time of the master node's time;
comparing the local time of the time of reaching the master node with the global time corresponding to the gap
Obtaining an error value;
feeding back the error value to the slave node, the slave node modifying the slave node according to the error value
The amount of time compensation.
Further, the local time of the time when the signal reaches the master node is obtained by the master node measuring a pilot signal.
By the closed-loop feedback mode, the local time of the plurality of slave nodes and the local time of the master node can be kept approximately consistent.
A time synchronization method for time division multiplexing carrier transmission system bus comprises the following specific implementation modes:
a bus of a time division multiplexing carrier transmission system comprises 1 main node and 98 slave nodes, one frame period every ten milliseconds is divided into 100 time slots, the length of each time slot is 0.1 millisecond, and the serial number is 0 to 99. The time slot 0 is used for the master node to send a synchronization signal, and the other 99 time slots are in one-to-one correspondence with the 99 nodes.
The master node's entity associated with the synchronization time is a clock source nominally 10 mhz and a corresponding modulo one hundred thousand counter.
The entity of each slave node relating to the synchronization time is a clock source with a nominal value of 10 mhz and a corresponding modulo one hundred thousand counter, register a and register B. The register A stores the local time when the last synchronous signal reaches the slave node, namely the count value of the modulo hundred thousand counter of the slave node, and the register B stores the estimated value (unit: 0.1 microsecond) of the propagation delay of the electromagnetic wave from the master node to the slave node. The default starting-up initial values of the register A and the register B are both 0.
3.1 modulo hundred thousand counter and local time, synchronous time
All nodes use a crystal with the nominal value of 10 MHz as a clock source, and all nodes count the period of the crystal in a mode of one hundred thousand, that is, each node is provided with a counter, and the value of the counter is increased by one every time the crystal with the nominal value of 0.1 microsecond vibrates every beat, and the count value becomes 0 when the count value reaches 99999. Each counting period is a frame period, i.e. ten milliseconds.
The counter of the master/slave node is the local clock of the node, and the counter value is the local time (unit: 0.1 microsecond).
When the master node is powered on, the value of the counter defaults to 0. Since the master node provides a system-wide time reference, its counter value is both the local time and the synchronization time.
For the slave node, the local time needs to be corrected according to the error value fed back by the master node, so as to obtain the synchronization time of the slave node, that is, obtain a value consistent or approximately consistent with the counter value of the master node.
3.2 updating of register A
When the counter value is 0, the master node starts to transmit a synchronization signal, wherein the synchronization signal is an OFDM signal and comprises a cyclic prefix, and the cyclic prefix is used for overcoming and relieving negative effects caused by multipath due to impedance discontinuity and the like of a transmission medium. The duration of the synchronization signal is no more than one slot interval, i.e. 0.1 ms.
The default initial value for the register a is 0.
After the slave node is started, the synchronization signal sent by the master node is searched, the local time (the count value of the modulo hundred thousand counter) corresponding to the time when the synchronization signal reaches the slave node is estimated, and the local time is assigned to the register A.
3.3 updating of register B
The default initial value for the boot-up of register B is 0.
The system allocates a slave node to transmit in a certain time slot. For example, the system allocates the slave node No. 1 to transmit in the 3 rd time slot, and the global time corresponding to the start of the 3 rd time slot is 3000. When the synchronization time obtained by the slave node 1 according to section 3.4 reaches 3000, the transmission is started. The transmission signal includes a pilot signal known to the master node, and the master node can estimate the time when the transmission signal from the slave node reaches the master node based on the pilot signal.
The master node measures the transmission signal of the slave node No. 1, estimates the time when the signal reaches the master node, compares the time with an expected value (3000) to obtain an error value, and feeds the error value back to the slave node No. 1.
After receiving the error value fed back by the master node, the slave node No. 1 corrects the value of the register B according to the following formula:
the register B value is actually assigned as the register B + k error value.
Where k is a coefficient greater than 0 and equal to or less than 1.
3.4 synchronization time generation method of slave node
The slave node calculates the synchronization time according to the following formula:
mod (count value of modulo hundred thousand counter-register A value + register B value, 100000)
Wherein, Mod is a modulus operation.
The above description is only a preferred embodiment of the time synchronization method applicable to the time division multiplexing carrier transmission system bus disclosed in the present invention, and not intended to limit the scope of the present invention, and all the equivalent structures or equivalent process transformations made by the present specification, or direct or indirect applications in other related technical fields, are included in the scope of the present invention.
Claims (3)
1. A time synchronization method suitable for a time division multiplexing carrier transmission system bus is characterized in that a slave node acquires a synchronization signal sent by a master node at fixed time, and a set of local time of the current time of the synchronization signal is corrected through local time corresponding to the arrival time of the synchronization signal and a propagation delay time compensation amount to form a closed loop method for self-updating of synchronization time of the slave node, wherein the acquisition of the propagation delay time compensation amount comprises the following steps:
the slave node sends a signal to the master node according to the distributed gap, and the master node acquires the local time of the time when the signal reaches the master node;
the master node compares the local time of the moment of reaching the master node with the global time corresponding to the gap to obtain an error value;
the master node feeds the error value back to the slave node, and the slave node obtains the time compensation amount according to the error value, wherein the formula is as follows:
the time compensation amount is the previous time compensation amount + k error value, where k is a coefficient greater than 0 and less than or equal to 1.
2. A method according to claim 1, wherein the synchronization signal is an OFDM signal.
3. The method according to claim 1, wherein the local time of the arrival time of the signal at the master node is obtained by measuring a pilot signal by the master node.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910722852.4A CN110460404B (en) | 2019-08-06 | 2019-08-06 | Time synchronization method suitable for time division multiplexing carrier transmission system bus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910722852.4A CN110460404B (en) | 2019-08-06 | 2019-08-06 | Time synchronization method suitable for time division multiplexing carrier transmission system bus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110460404A CN110460404A (en) | 2019-11-15 |
| CN110460404B true CN110460404B (en) | 2021-07-02 |
Family
ID=68485203
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910722852.4A Active CN110460404B (en) | 2019-08-06 | 2019-08-06 | Time synchronization method suitable for time division multiplexing carrier transmission system bus |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110460404B (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106603367A (en) * | 2017-02-28 | 2017-04-26 | 北京艾利特科技有限公司 | CAN bus communication method for time synchronization |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101431795B (en) * | 2008-11-29 | 2012-10-10 | 中兴通讯股份有限公司 | Time synchronization method and apparatus |
| CN101945305A (en) * | 2009-07-09 | 2011-01-12 | 大唐移动通信设备有限公司 | Method and system for realizing time synchronization |
-
2019
- 2019-08-06 CN CN201910722852.4A patent/CN110460404B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106603367A (en) * | 2017-02-28 | 2017-04-26 | 北京艾利特科技有限公司 | CAN bus communication method for time synchronization |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110460404A (en) | 2019-11-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7184920B2 (en) | Delay measurement system | |
| US7751448B2 (en) | Method of symbol timing synchronization in communication systems | |
| US6816818B2 (en) | Method, clock generator module and receiver module for synchronizing a receiver module | |
| US20090310625A1 (en) | Method for distributing a common time reference within a distributed architecture | |
| CN105009465A (en) | Performing upstream symbol alignment under fext | |
| JP6227888B2 (en) | Communication system, synchronization system, and communication method | |
| CA2936249C (en) | System and method for time adjustment in a time synchronized channel hopping network | |
| CN113541940A (en) | Time synchronization method for quantum key distribution | |
| CN110460404B (en) | Time synchronization method suitable for time division multiplexing carrier transmission system bus | |
| EP1115001A1 (en) | Trigger node for measurement system | |
| CN101001232A (en) | Sending method and system for synchronous signal | |
| CN111711224A (en) | Synchronous processing method for output voltage and carrier signal when alternating current power supplies are connected in parallel | |
| US8085700B2 (en) | System node and method for providing media arbitration | |
| CN105765913A (en) | Interference mitigation apparatus and interference mitigation method for home network transmission line, and communication system using same | |
| Cena et al. | The reference-broadcast infrastructure synchronization protocol | |
| KR101474520B1 (en) | Device for mitigating interference home network transmission line, method for mitigating interference and communication system using the same | |
| CN102983959B (en) | Method for realizing one-step mode and two-step mode for PTP (precision time synchronization protocol) in a plurality of MAC | |
| WO2015086401A1 (en) | Timing control in an industrial control system | |
| US20220239439A1 (en) | Channel Sounding for Distributed Transmission | |
| US11343007B2 (en) | Time synchronization method and device | |
| KR100304776B1 (en) | Synchronization system and method, and recording medium | |
| CN102546144A (en) | Method and device for synchronizing information | |
| CN101296068A (en) | Digital synchronization receiving device and signal processing method | |
| CN101114899A (en) | Beacon transmitting method in mobile multimedia broadcasting system | |
| JP5950776B2 (en) | Time division data communication system and time division data communication device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20200220 Address after: 430000 room 1403, building B1, Wuhan future science and Technology City, No. 999, Gaoxin Avenue, Donghu New Technology Development Zone, Wuhan City, Hubei Province Applicant after: Wuhan Juyi Microelectronics Co., Ltd Address before: Room 119, Zhongchuang Building, No. 2 Darui Road, Guandong Industrial Park, Donghu New Technology Development Zone, Wuhan City, Hubei Province Applicant before: Wuhan Sheng Rong Rong Rong Microelectronic Technology Co., Ltd. |
|
| TA01 | Transfer of patent application right | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |