CN205725784U - NTP time server in high precision - Google Patents

Abstract

This utility model provides a kind of high accuracy NTP time server, satellite clock processes FPGA unit and is connected with DCLS reception unit, DCLS receives unit and connects the Big Dipper/gps satellite reception unit and main CPU unit, main CPU unit is also connected with the Big Dipper/gps satellite and receives unit, satellite clock processes the time signal of FPGA unit output and tames time holding unit OCXO agitator by DA driver element, it is characterized in that, NTP signal remembers timestamp at ethernet physical layer unit subscript, and by being unpacked by DCLS after hardware FPGA unit high speed processing and NTP time service administrative unit output time.This utility model mode based on FPGA hardware, completes the design of NTP time server and the implementation of NTP time service task, it is provided that a kind of high accuracy NTP time server, it is possible to realize Microsecond grade time synchronized in the range of LAN.

Description

NTP time server in high precision

Technical field

This utility model relates to letter when a kind of reception Beidou II time signal, output nanosecond NTP network pair Number time server, particularly relate to a kind of utilization and beat the time accuracy treatment technology of timestamp in physical layer, Replace traditional application layer and beat the treatment technology of timestamp, belong to communication technical field.

Background technology

Along with development and the progress of society of science and technology, many industries are more and more higher to the requirement of time precision.? The every field such as electric power, traffic, communication, finance, precise time signal can ensure that various automatization sets Standby is properly functioning, and the time difference of 1 second is likely to cause data statistics to be slipped up, and causes and cannot retrieve Economic loss.

Network Time Protocol full name NTP (Network Time Procotol).Its purpose is to pass through network Transmission is unified, the time of standard.General concrete implementation scheme is to specify some clock sources on network, passes through Network transmit synchronizing signal, it is achieved between different geographical clock be synchronized to UTC Universal Time Coordinated UTC, its precision exists Up to 0.1ms in LAN, its precision of the most most of place can reach 1-50ms.

If client computer needs to be carried out pair by network and server, client computer first sends one and asks same step number According to bag, and on packet, stamp local time stamp T1.When server receives this packet, immediately beat The local zone time T2 of upper server, through server process, server sends a synchrodata to client computer Bag, this packet comprises T1, T2 and the time T3 of server transmission packet, when client computer receives this number During according to bag, immediately stamp local time stamp T4.

Client computer is calculated by formula, finally: skew offset=[(T2-T1)+(T3-T4)]/2.

As can be seen from the above equation, skew is the most relevant to four markers, and unrelated with propagation delay time size.

Calculate client-server time offset after, by complicated adjustment technology, client computer is the most permissible Realize the time synchronized with server.

When NTP is operated in broadcast mode, no matter server Client Work is in what mode, when actively sending Between information, client's thus information adjusts oneself time, and now network delay is ignored, and therefore damages on accuracy Lose, only can meet the application of Millisecond even second level；When being operated in Client/Server, client computer is to service Device sends a synchronous request signal, and the packet containing temporal information is sent to client computer by server again, logical Crossing calculating, client computer realizes the time synchronized with server.

NTP technology is used to realize precise synchronization, it is necessary to the problem first solving time delay.Time Postponing generally to be made up of 2 parts, a part comes from the delay in external network transmission, in a part comes from During portion's protocol layer encoding and decoding markers.The calculating of Network Time Protocol itself just adds Network Transmission Delays Factor, as long as therefore NTP has outstanding synchronization computing capability from clock, transmission delay can't be to synchronization accuracy Producing a very large impact, the time delay now produced during internal agreement layer encoding and decoding markers is to affect network The principal element of synchronization accuracy.In traditional NTP network, if NTP is between clock and ntp server Be spaced multiple level (stratum), owing to when each node encoding and decoding, timestamp produces time delay, therefore this The time precision that individual NTP is obtained from clock is poor.

Standard Network Time Protocol pair time precision depend primarily on the delay jitter receiving with sending in protocol stack, Owing to application layer is top, through the impact of the multi layer protocol stack shakes such as Internet, transport layer, expression layer, Pair time precision low.

It is to use hardware currently for the solution that this problem low of precision during standard NTP pair is universal (Carrier-Class) NTP technology, drives layer to beat markers at Ethernet, fundamentally solves to come from internal association The time delay that during view layer encoding and decoding, timestamp produces.Pair time precision depend in the interrupt service routine of Ethernet The disconnected response time.In conjunction with the precision frequency stabilization of agitator up to 1us.

Use the equipment of Carrier-Class NTP technology, when data are labeled with after physical layer has encoded immediately Markers, therefore substantially reduces the high time delay that tradition NTP technology causes because beating markers at software layer.Another Planting submicrosecond level high-accuracy network Time synchronization technique PTP technology is also to have employed the target side when hardware layer is beaten Precision when method is greatly improved network pair, therefore, Carrier-Class NTP technology is that one have employed NTP Agreement, technical convergence PTP realizes the technology of precise synchronization in catenet.

Additionally, traditional NTP synchronizes to be that hierarchical layered synchronizes, such as stratum-1, stratum-2, stratum-3 Deng, the number of plies between client and server is the most, and its precision is the poorest, because every Primary Clock is in encoding and decoding Time timestamp and transmission time all can produce time delay.And generally only with 2 layers of configuration in Carrier-Class NTP system, Greatly improve the time precision of client acquisition (if when equipment is all in stratum-1, then can Obtain the highest precision).When implementing time synchronized in a large-scale network, we are generally in several keys Node on configure ntp server, the most both reached the purpose of redundant configuration, effectively reduced again service Device, to the transmission node between client, reduces the delay caused because node.

The equipment using Carrier-Class NTP technology the most all have employed the hard of preferable signal handling capacity Part equipment, the ability processing signal in real time powerful and at a high speed also makes synchronization accuracy improve further, also protects simultaneously Demonstrate,prove and can provide precise time benchmark to substantial amounts of equipment in catenet.

Summary of the invention

The technical problems to be solved in the utility model is to realize Microsecond grade time synchronized in the range of LAN.

In order to solve above-mentioned technical problem, the technical solution of the utility model there is provided a kind of high accuracy NTP Time server, unpacks including independent DCLS and NTP time service administrative unit and satellite clock process FPGA Unit, satellite clock processes FPGA unit and is connected with DCLS reception unit, and DCLS receives unit and connects north Bucket/gps satellite receives unit and main CPU unit, and main CPU unit is also connected with the Big Dipper/gps satellite and receives single Unit, satellite clock processes the time signal of FPGA unit output and tames time holding list by DA driver element Unit's OCXO agitator, it is characterised in that NTP signal remembers timestamp at ethernet physical layer unit subscript, And by being unpacked by DCLS after hardware FPGA unit high speed processing and NTP time service administrative unit output time.

Preferably, described satellite clock process FPGA unit is also connected with display and keyboard unit.

This utility model passes through Carrier-Class NTP technology, mode based on FPGA hardware, completes NTP The NTP time server design of time service task and implementation, it is provided that a kind of high accuracy NTP time server, It is capable of Microsecond grade time synchronized in the range of LAN.

Accompanying drawing explanation

Fig. 1 is NTP fundamental diagram, and the t in figure is time delay；

A kind of high accuracy NTP time server that Fig. 2 provides for this utility model；

Fig. 3 is that hardware FPGA unit implements.

Detailed description of the invention

For making this utility model become apparent, hereby with preferred embodiment, and accompanying drawing is coordinated to be described in detail below.

As in figure 2 it is shown, this utility model provides a kind of high accuracy NTP time server, including independent DCLS unpacks and NTP time service administrative unit and satellite clock process FPGA unit, and satellite clock processes FPGA unit receives unit with DCLS and is connected, and DCLS receives unit and connects the Big Dipper/gps satellite reception unit And main CPU unit, main CPU unit is also connected with the Big Dipper/gps satellite and receives unit, and satellite clock processes FPGA The time signal of unit output tames time holding unit OCXO agitator, satellite by DA driver element Clock processes FPGA unit and is also connected with display and keyboard unit.NTP signal is at ethernet physical layer unit Subscript note timestamp, and by being unpacked by DCLS after hardware FPGA unit high speed processing and NTP time service pipe Reason unit output time.

In conjunction with Fig. 3, hardware FPGA unit is accomplished that single NTP time service module supports two network interfaces at present. It is contemplated that the promptness sent, it is not considered as the page alternately at transmitting terminal.

Content (address space 0x0-0x7f) in RAM1/3:

Word1: preserve the data packet length (in units of word) received from PHY；

Word2 and later preserve the data received from PHY.

Content (address space 0x80-0xff) in RAM2/4:

Word1: preserve the data packet length (in units of word) being ready for sending PHY；

Word2 and later preserve the data being ready for sending in PHY.

Dual port RAM 51 and RAM52 is used to preserve the CPU configuration information to FPGA, has self-defined Data structure.Owing to the operation of this RAM can be affected the various operations of port server, so suggestion When it is operated by CPU, corresponding miniport service should be stopped.RAM51 correspondence PHY interface module 1；RAM52 Corresponding PHY interface module 2.Same RAM block can be used inside FPGA.

Dual port RAM 6 is used to preserve the various information that CPU needs FPGA to send, and has self-defining data Structure.This space is divided into two pages, is used for synchronizing the write operation of CPU and the read operation of FPGA.Page two In face, content is similar, and CPU can only revise a part of content therein.

In order to process when completing high-precision NTP time pair, this utility model takes satellite clock and processes single Unit and the processing mode of NTP processing unit independence, NTP port number when thus can increase very easily pair. Satellite clock processing unit uses the mode of phaselocked loop feedback to process OCXO and tames algorithm, exports DCLS signal energy The stable level at ＜ 100ns.NTP processing unit uses input DCLS signal and 20M, and (satellite clock processes single The clock that unit tames) signal, additionally serial ports part is that webmaster uses.By parsing being equivalent in DCLS 1PPS and TOD signal, completes the time service work of NTP module section.

NTP exports clamp and uses hardware to beat the technology of timestamp by this utility model, it is to avoid the time beaten by software Uncontrollable time delay that stamp causes, have successfully completed the NTP technology of nanosecond, for milli under software mode The NTP of second level, has qualitative leap.The employing of hardware NTP technology can also resist network storm, and these are all The technology that software NTP mode does not has.

Claims (2)

1. a high accuracy NTP time server, unpacks including independent DCLS and NTP time service administrative unit And satellite clock processes FPGA unit, satellite clock processes FPGA unit and is connected with DCLS reception unit, DCLS receives unit and connects the Big Dipper/gps satellite reception unit and main CPU unit, and main CPU unit is also connected with The Big Dipper/gps satellite receives unit, and satellite clock is processed the time signal of FPGA unit output and driven by DA Moving cell tames time holding unit OCXO agitator, it is characterised in that NTP signal is at Ethernet physics Layer unit subscript note timestamp, and by being unpacked and NTP by DCLS after hardware FPGA unit high speed processing Time service administrative unit output time.

2. a kind of high accuracy NTP time server as claimed in claim 1, it is characterised in that described satellite Clock processes FPGA unit and is also connected with display and keyboard unit.