OCXO时钟修正机制在电法勘探采集中的应用研究

为解决GPS易受外界环境影响,同步授时易失锁这一问题,设计出一种基于FPGA的保证GPS与OCXO协同工作的高精度同步授时解决方案.采用在FPGA内部构造延迟线的方法来对时间间隔进行测量,使时间测量精度可达到71ps和10ps,从而确保了时间间隔测量的高准确性.以GPS提供的秒脉冲1PPS作为标准信号对OCXO的频率进行校准,再在FPGA中采用均值滤波算法对1PPS信号引入的随机噪声进行压制,实际验证表明,该设计具有很好的频率校准效果.FPGA每完成一次校准就对同步修正一次,保证了GPS在任何时候失锁时,本地秒脉冲都与1PPS具有很高的初始同步精度.当完成频率校准后,GPS分别失锁150min,6h,12h,24h,同步精度仍可达到410ns,1.6us,2us和33us.这优于V5-2000的同步精度.长期实测表明,该方案可以很好地结合GPS授时和OCXO授时的优点,解决了GPS同步授时存在的问题.这不仅满足所有电法勘探的分布式采集系统对同步授时的精度要求,而且适用其它需要高精度同步授时的工业领域.该方案的设计只在一片FPGA中完成,这最大限度地减少了外围器件的消耗和外围电路的复杂程度,降低了功耗.     

基于Protues的GPS守时授时时钟装置的设计与仿真

本文设计了一种以GPS时间为标准信号的守时授时时钟装置,阐述了该装置的硬件组成、软件实现、程序流程图及程序说明,介绍了一种应用较广的新兴单片机仿真软件—Protues。经仿真表明,本设计实现了守时授时功能,可为其他设备提供高精度时间信号和秒脉冲信号。     

采用同步计时提高GPS钟的时间脉冲输出精度

全球定位系统GPS (GlobalPositioningSystem)是美国研制的导航、授时和定位系统。论述了采用GPS时间同步技术 ,实现GPS钟输出时间脉冲精度小于 10 -6s的方法。指出仅用软件计时 ,GPS钟输出时间脉冲精度将大于 10 -5s;而采用软件、硬件相结合的GPS时间同步技术 ,能充分利用单片机的资源 ,弥补软件计时的不足 ,从而大幅度提高了GPS钟时间脉冲的输出精度 (达到 0 5× 10 -7s)。     

GPS授时技术在地震观测中的应用

在地震观测中，时间基准测量的精度非常重要。我们利用全球定位系统（ＧＰＳ）设计完成了数字地震记录仪的实时在线授时系统，提高了时间服务精度。本文详细介绍了利用ＧＰＳ授时的基本原理，给出了我们研制的数字地震仪中授时系统设计的理论计算和具体的同步算法和程序以及硬件设计框图。     

新一代时间服务器——GPS同步钟

新一代时间服务器——ＧＰＳ同步钟赵华冯玉华张志中（中国北京１０００８１国家地震局地球物理研究所）１ＧＰＳ同步钟的特点ＧＰＳ同步钟是根据国家地震局“台网改造”项目而研制的新一代基本台网时间服务器。目前我国各地震台站均采用ＢＰＭ授时方式，有些台站由于受...     

长距离数据传输抗干扰技术研究进展

研究高温高压高湿环境下,长距离数据传输抗干扰技术,设计有效的数据传输方式,组建稳定高效的传输系统是井下甚宽频带地震仪研制项目的重要环节。长距离数据传输抗干扰技术研究进展主要包括:低功耗、小型化、高分辨率、大动态范围的数据采集核心模块,传输抗干扰技术,数据传输协议及高精度授时等。      

地震台如何对时

在地震观测中,准确的对时十分重要。目前国内外授时台所播发的标准时间,包括两种不同的时间系统:一种是以地球自转为标准所测定的时间,并作了地球极移影响修正后的世界时UT_1时间系统;另一种是以高精度的原子时秒长为基础,与UT_1时间保持协调,偏离在±0.9秒以内的协调时UT_c时间系统。按国家地震局的规定和国际资料交换的统一需要,在地震观测中统一使用UT_c时间。目前我国的     

分布式多通道电法电磁法数据同步采集系统

采集系统是电磁法仪器的重要组成部分,设计出高精度、低功耗的分布式采集系统是电磁法仪器研制的重点和难点.本文设计的采集系统集成了6个采集通道,每个采集通道的A/D转换器都选用了32位的ADS1282,并通过DAC1282来提供ADS1282校准和自检所需要的外部信号.采集部分的控制中心选用了MachXO2 ZE系列这款功耗极低的CPLD.为了保证同步采集的精度,设计中采用了GPS和OCXO协同授时的方案来提供同步时钟.采集系统具备MT、CSEM、SIP等测量功能.测试结果表明,本采集系统同步精度维持在1E-11以下,待机状态下功耗为0.32 W,运行功耗2.76 W,各通道短路噪声值均在μV级,信噪比在118 dB附近,满足设计要求.     

一种新型的钟差测定仪器——捕捉笼式数字秒差计

近年来,为了提高地震记录的时间服务质量,各类石英钟陆续问世,对钟的技术要求也越来越高。中国科学院陕西天文台发播的“BPM 标准时间、标准频率”授时信号,系国家确认的高精度时间基准。我国地震系统就是采用这个标准来测定时钟的“钟差”。测量钟差的仪器是“毫秒计”、“钟差计”等时间间隔测定器(基本原理见《地震》1981年第4期、第5期刊载的“数字对钟技术”一文)。测定器所采用的是一种基本的测定时间差的方法。但是,它不具备有分辨相关秒脉冲的能力,在使用中,仪器可能记录的是非相关     

控制海底电磁激发脉冲发射的时间同步技术

为达到海洋可控源电磁探测和远参考测量的目的,研究控制海底电磁激发脉冲发射的时间同步技术,包括发射前与GPS的对钟技术和发射中的同步技术,保证仪器工作的时间和公共的时间基准GPS信号保持精确一致,为后期的数据处理解释提供统一的时间坐标.对钟技术是指,在海洋调查船上完成仪器内部RTC芯片分频所得的秒脉冲信号RTC_PPS与GPS秒脉冲信号PPS时钟沿的同步;同步技术是指,海底工作过程中,仪器在预定的时钟沿将可控源信号精确发射出去.本论文采用CPLD芯片、RTC芯片、GPS模块和AVR单片机来完成对钟和同步模块的设计.     

数字化力平衡加速度传感器设计与应用

在传统模拟式力平衡加速度传感器技术的基础上,通过改进传感器机械结构、内嵌高精度采集器等方法,设计了1款数字化力平衡加速度传感器。针对传感器中三通道模数转换要求完全同步、高分辨率、高采样率等技术难点,本文选用高精度ADS1294模数转换器,以同1个驱动信号完成三通道同步模数转换,实现低干扰、高分辨率的模数转换;采用高速ARM微处理器对模数转换数据进行大容量数据存储、高速数据通讯、数据处理、波形显示和电源管理;采用高精度线性电源芯片作为可开关控制的高精度电源,实现仪器整机低功耗管理。该数字化力平衡加速度传感器实现了大动态测量范围、三通道同步数据转换、高达1000Hz的采样率,且具有网络通讯接口等功能。     

地震地磁场野外观测同步控制系统研制与应用

针对地震地磁野外观测的需求,开发研制了一种基于无线网络的野外同步观测系统。该系统主要由接口单元、采集控制(CPU)单元、无线单元、传输网络、计算机控制中心等组成。该系统操作简单,实用性强,具有远程唤醒及休眠、校时等服务功能,也可应用到地磁台阵的数据传输与同步工作中。     

A SYSTEM OF CAPACITIVE HIGH-VOLTAGE PULSE RECHARGE/DISCHARGE AND ITS IMPLICATION ON EXPERIMENTALLY TRIGGERED EARTHQUAKE

An external small disturbance may trigger seismic events when the fault is in a critical state. The problems related with earthquakes triggered by the dynamic stress such as blasting loads, impact loads, volcanic eruptions and strong earthquakes, have usually drawn wide concerns in earthquake science, and the corresponding research contents are quite extensive, including earthquake triggering mechanisms, triggering earthquake uncertainty, aftershock triggering, and so on. Among them, experimental research is an important way to understand the stress triggering conditions and physical mechanisms, such as the influence of load disturbance on fault friction traits, the influence of periodic disturbance of tidal stress on fault instability, etc., all of which can be gained through experimental investigations. Among them, "how to trigger" is a basic scientific problem to increase the understanding of earthquake prediction theory, thus receiving more attention. There are also some studies that focus on "what happened after the trigger", that is, the sliding instability generated by the triggering method, and then the evolution characteristics of the sliding instability process. The well-known experimental study of the super-shear rupture process is conducted by using the electric explosion method to trigger the fault instability, and the high-speed camera records the super-shear rupture during the fault instability. This means that when the trigger source is controllable, it is possible to generate different types of instability processes, and then to explore which earthquakes will be triggered at different time and space positions under different stress states by means of active triggering. The study of stability analysis and instability process has important scientific significance.A stable system of capacitive high-voltage pulse discharge and recharge is one of basic techniques for studying the triggered earthquakes in laboratory. Based on the wire electric explosion method, this paper develops a controllable trigger experiment system. By designing a new capacitive high-voltage pulse charge and discharge system, while considering the actual needs of monitoring and system timing, multiple functions are integrated into one system. Functionally, in addition to realizing the dynamic loading and unloading function of the wire electric explosion method, the discharge process can be monitored, and the triggering, synchronization and timing signal output is performed with other observation systems, thus realizing the whole process monitoring of the dynamic disturbance action. After testing, the following functions are achieved:1)The voltage and current of the high-voltage charging power supply system can be automatically adjusted, and the system can be shut off after charging; 2)Control modes include manual and remote controls. These two modes can control the recharge, release and pulse discharge of the high voltage capacitor; 3)The system can produce multi-channel synchronous output, which satisfy multiple systems working together. In particular, the remote sensing method greatly improves the experimental maneuverability and security; 4)The system has multiple sets of gas discharge tube to trigger discharge, with a wide range of discharge voltage of 500~5 000V; 5)Roche coil resistance integral current detection can meet the transient resistance, large current detection. Test results indicate that this system has good repeatability and stability with the same discharge energy and discharge energy regulator, which is conducive to carry out single channel trigger of high-pressure discharge experiment. In short, the new charging and discharging system can meet the requirements of experimental study of triggering earthquake. In addition, this system can be used to generate the stress disturbance under certain static and dynamic conditions, and then judge whether this kind of mechanical conditions in active fault systems is currently stable.In short, a controllable single-shot discharge system is developed by a capacitive high-voltage pulse discharge system, which provides a good technical basis for experimental research on triggering earthquakes. In addition, the new system also has application significance:1)multiple triggering output can simultaneously start multiple systems and improve the efficiency of observation. Fault instability is a characteristic of transient response, so, its observation requires high-speed acquisition equipment, which is difficult to control on observation; the trigger system is controllable, with active synchronization observation using physical parameters; 2)stress disturbance can be triggered under static and dynamic loads to detect the safety and stability of the fault system with active trigger.     

脉冲中子双伽马谱饱和度测井方法及数值模拟研究

脉冲中子双伽马谱饱和度测井方法是利用特定的脉冲和测量时序设计,采用远、近伽马探测器记录非弹性散射和俘获伽马能谱以及伽马射线时间谱,通过获取C/O和地层宏观俘获截面等信息来确定地层含油饱和度.采用大直径仪器和BGO晶体探测器时,其采集的非弹性散射和俘获伽马能谱计数统计性优于国外仪器,重复脉冲发射中子后伽马射线时间谱仍满足指数衰减规律,且能使伽马射线时间谱的道计数累积,计数统计性好于常规中子寿命测井,得到的地层宏观俘获截面与单脉冲发射近似相同.在地层孔隙度未知的情况下,利用C/O和地层宏观俘获截面交会技术可以定量确定含油饱和度.     

A SUPER-DYNAMIC DEFORMATION MEASUREMENT SYSTEM WITH LONG-TIME PARALLEL CONTINUOUS ACQUISITION

In the simulation experiments of earthquakes in laboratory, the instability slip or rupture events are obtained through steady state loading to simulate earthquake processes. In the experiments, steady-state deformation and unstable sliding occur alternately. It is hard to determine the origin time and duration of the instability event of fault, and there may be many instability events in one experiment. Therefore, in order to ensure that sufficient data is obtained at the extremely short instability moment to analyze the mechanical process of the earthquake source, the data acquisition system is required to continuously collect data at high-speed from the beginning of the experiment until the end, and the lasting time can be more than ten hours, so it requires huge storage space. Although the upper frequency limit of the instability signal is unknown exactly, but the previous experiments have shown that the frequency of the signal will reach hundred to several kilohertz, so the sampling frequency of the data acquisition should be above megahertz. In this case of long-time continuous high-frequency data acquisition, it is still necessary to maintain a high signal-to-noise ratio. Furthermore, previous studies have proved that the source mechanics field has a complex spatial structure, which is difficult to describe with a few measuring points, and it is necessary to perform simultaneous measurements of the source mechanics field for dozens or more measuring points. The combination of long-term continuous recording, high-resolution high-frequency sampling and multi-point simultaneous measurement poses a huge challenge to the technical indicators of the observing system. With the method for composing distributed synchronous acquisition machine group by using multiple high-resolution high-frequency sampling computers, a super dynamic deformation measurement system of high signal-to-noise ratio, which features 64-channel, 16-bit resolution, 4MHz sampling frequency, and parallel continuous acquisition with tens of hours was developed. This system can realize the synchronous acquisition of various signals, such as strain, acoustic emission, electromagnetic waves and displacement, so it is convenient for analyzing the conversion relationship between various physical quantities.     

CORS观测网络地壳运动监测系统研制及应用

以四川CORS观测网络为数据基础,结合GPS高精度数据处理技术及B／S技术架构,设计并实现了一套地壳运动在线监测系统。该地壳运动监测系统以GAMIT／GLOBK为数据处理引擎,实现各CORS站数据的高精度自动化解算,并通过WEB技术实现测站信息、基线序列以及坐标序列等的信息可视化表达。试验结果表明,该系统具备较好的运行稳定性和友好的人机交互性,可实现自动化的区域地壳运动监测。     

时序数据库在海量地震波形数据分布式存储与处理中的应用初探

通过分析时序数据库的技术特点和海量地震数据存储和处理的需求,设计和实现了基于时序数据库的地震波形数据存储和处理系统。经过开发、测试和应用比较,新的地震时序数据库系统具有高可用、实时存储吞吐量大、历史数据压缩率高、分布式处理速度快等优势,能够较好地解决地震波形数据体量激增带来的存储和处理困难问题。     

earthquake disaster rapid assessment for emergency response supported by high-precision data of hazard bearing body

The earthquake disaster rapid assessment(EDRA)is the core technical support for the post-earthquake emergency response. At present, with the popularization of high-precision population, social and economic data, most of the subordinate units of China Earthquake Administration(CEA)have heightened the precision of hazard bearing body data used in EDRA from the original county-level precision to the 30″×30″ precision. However, while the precision of fundamental data has been heightened, no efforts have been made to improve the main algorithms and the technical process of EDRA. It turns out that the assessment has become more accurate, but the problems of the time-consuming process(10-20 minutes, probably 20 minutes or more in great earthquakes)and the low-precision losses distributions that exposed in EDRA supported by county-level precision data remain unresolved.This paper introduces the high-precision(30″×30″)hazard bearing body data, and describes the principle of EDRA and its implementation under the support of county-level precision data at first. Then the paper elaborates the principle of improving EDRA's data foundation using high-precision hazard bearing body data, the principle of improving the computation efficiency and persisting the data precision in the assessment process by means of the cell-to-cell grid algebraic operation, and the method for improving the assessment speed through the segmentation and reorganization of the technical process of EDRA.It is validated that through the improvements, the EDRA has become more accurate and much less time-consuming(less than 1 minute), and is able to output high-precision(30″×30″)distributions of seismic losses. The high-precision hazard bearing body data of wide range are the simulated data but not the survey data. Though the data have been simulated based on the census data, there is still a gap between their accuracy and the real situation. Further research and optimization on the data are needed.     

瞬变电磁采样函数优化法降噪技术

常用的双极性同步采样方法对瞬变电磁系统的观测噪声具有一定的抑制作用,但在实际工作中其噪声抑制能力仍显不足.本文在双极性同步采样方法基础上提出一种优化方法,以提升瞬变电磁系统的噪声抑制能力,即:通过对取样道加高斯窗函数的方式,赋予取样道内各采样点合适的累加权重,提升系统对取样道内高频噪声的抑制能力;使用高斯窗函数与梳状滤波器构造复合窗函数,通过对包含所有叠加周期的完整观测序列加复合窗函数的形式优化各周期的叠加权重,提升系统对实际工频噪声的抑制能力.对优化前后不同采样函数的谱特性及野外实测数据的处理效果进行比较,结果表明本文提出的方法较传统双极性同步采样方法具有更强的噪声抑制能力.