GPS共视法远距离时间频率传递技术研究

GPS共视法时间频率传递技术是目前时间频率远距离高精度量值传递的主要方法之一.详细介绍了共视法原理、GGTTS格式各参数的意义和计算方法.阐述了中国计量科学研究院近年来GPS共视法远程校准技术研究内容,介绍了NIM时间多通道接收机的基本构成和实际测量比对结果以及最终数据处理算法.     

GPS共视接收机硬件控制和数据实时处理解决方案

GPS共视法技术用于测量位于不同地方的两个频率源。在测量过程中，每个地方各有1个频率源和1台共视接收机。共视接收机测量本地频率源与GPS信号，并保存测量结果。经过一段时间的测量后，汇总两地的测量数据，经数据处理去掉GPS信号．就可得到两地频率源的比较结果。GPS共视法是国际上流行的远距离时间频率传递技术。是目前时间频率远距离量值传递的主要工具之一，它的核心是GPS共视法接收机及后处理算法。     

基于RINEX文件的时间频率标准远程校准方法

时间频率在许多领域,尤其是高科技领域中的重要性使时间频率标准得到了快速发展,随之而来是对这些时间频率标准校准的问题。由于国内时间频率校准服务领域现存校准方法都存在不能远程校准或精度不高等缺陷,本文提出了一种基于GPS接收机记录的RINEX文件的时间频率标准远程校准方法以图解决此问题,实施了具体实验并得到了积极的结果。     

青岛远程时间频率溯源传递系统及其应用

青岛市计量技术研究院以可信的时间频率标准装置(NIMDO)为核心,建立了高准确度的远程时间频率溯源系统,实现了时间频率实时溯源至原子时标国家计量基准UTC(NIM)。整个系统与UTC(NIM)的时间偏差在±6ns内,时间稳定度(1天)优于0.3ns,频率稳定度(1天)优于5e-15,具有较高的稳定性和准确性。同时,利用远程时间频率溯源传递系统,可为交通、电网、电力等众多行业提供授时及检定、校准、测试服务。     

GPS在时间频率测量中的应用简介

介绍了怎样将GPS(全球定位系统)的卫星信号应用在时间和频率计量中,讨论了GPS接收机如何实现时间同步和频率校准,阐明了GPS在时间和频率测量中应用的几种类型.     

基于多普勒频移观测值的机动车GPS测速仪校准技术的研究

提出了一种基于现场GPS信号定标的实验室校准方法.利用3光束光遮挡测速标准装置在测试现场对卫星GPS信号直接进行速度实测定标,通过GPS记录仪保存,然后在实验室进行GPS信号回放来完成高精度机动车GPS测速仪在40～180km/h范围内特定速度值的实验室精确校准,溯源至长度和时间计量基本单位.对同一台高精度机动车GPS测速仪的现场道路实际检测和实验室GPS信号回放检测的比对试验,车速在180km/h时采用该方法的速度校准不确定度优于0.1%(k=2).     

高精度机动车GPS测速仪校准技术研究

为了建立针对高精度机动车GPS测速仪的溯源途径,本文介绍了高精度机动车GPS测速仪的两种实验室校准技术,在(40~180)km/h范围内特定速度点,对同一台高精度机动车GPS测速仪分别进行了实验室模拟测速误差校准、现场道路实际测速误差校准和实验室GPS信号回放校准,并分别提供了采用该校准方法的不确定度评定实例结果,验证了高精度机动车GPS测速仪的模拟测速误差校准不确定度优于0.02%(k=2),卫星信号回放测速误差校准不确定度优于0.10%(k=2).两种校准方法均能够对高精度机动车GPS测速仪进行有效校准.经过校准的高精度机动车GPS测速仪在可用卫星数不少于6颗的使用环境下,能够满足现场测速标准器具的使用要求,具有广阔的应用前景.     

GPS接收机相关校准规范中不确定度评定的有关问题探讨

JJF1214-2008《长度基线场校准规范》和JJF1118-2004《全球定位系统(GPS)接收机(测地型和导航型)校准规范》分别为GPS接收机校准装置和校准测量的技术依据,两个规范分别就装置和计量器具校准的测量不确定度进行了评定。然而令人不解的是,同样以测量距离为5km为例,校准用GPS接收机的标准不确定度(以下简称"基线不     

一种改进的手持GPS接收机校准方法探讨

简述了现有手持GPS接收机的校准方法和过程,分析了其校准存在的问题。为确保校准结果的客观准确性,提高用户使用的可靠性,引入"实测拟合法"对手持GPS接收机进行校准,并对该校准方法的有效性进行了分析和对比实验。实验对比结果表明,该校准方法更为客观合理,普适性强,能更准确地反映手持GPS接收机的真实定位性能,具有一定的参考作用。     

两岸GPS接收机校准异同分析

大陆与台湾地区的计量技术机构在GPS接收机的校准方法上存在一定的差异,本文阐述双方在GPS接收机校正标准装置、标准溯源和量传、校准参数、校准方法和不确定度分析上的异同,通过综合比较,分析各自的优缺点及合理性.为双方在计量技术上的交流合作打下基础,同时为双方在GPS接收机计量校准方法和检定校准证书的相互认可做铺垫.     

卫星导航接收机时延测定技术研究

利用卫星导航接收机进行高精度授时同步是一种简单有效的授时同步手段。导航接收系统时延的精确测量是进行高精度授时的前提,其输出秒脉冲信号的时延更是影响远距离授时、时间同步的关键。围绕卫星导航接收系统时延的测定,通过分析卫星导航接收机的时延构成及特点,建立了卫星导航接收机的时延构成模型,制定了便于操作的卫星导航接收机时延测定的方法,搭建了一套完整的卫星导航接收机时延测定系统,并对系统进行了标定和实验验证。     

基于激光干涉法的一次冲击微分加速度动态特性校准

介绍了利用激光光栅干涉技术进行冲击加速度校准的一种方法,并着重讨论微分加速度的动态特性校准。将冲击加速度和微分加速度直接溯源于基本量和单位(时间和长度);叙述了差动式光栅激光干涉冲击校准装置的原理,介绍了使用调频信号的数字化解调方法和模式识别方法实现数据处理的基本过程;最终给出了被校准的加速度计的微分加速度的频率特性曲线和传递函数的实验结果。结果表明,该方法可以进行加速度计之微分加速度的动态特性的校准测试。     

Time transfer using multi-channel GPS receivers

This report is on time transfer experiments using a Global Positioning System (GPS) receiver constructed using a commercial GPS "engine" and a standard PC. The receiver measures the time difference between the local clock and a 1 pps signal synchronized to GPS time using data from up to 8 satellites. The receiver also reports the difference between GPS time as estimated using each of the satellites being tracked and the composite output pulses that have a rate of 1 Hz (1 pps signal). These data can be used to construct the standard 13-minute tracks as defined in the BIPM standard; the same data also can be averaged in other ways that make better use of the multi-channel capabilities of the hardware. The 13-minute averages can be directly compared with standard time-transfer receivers using common-view analysis. The results of the tests suggest that the methods currently used for national and international time and frequency coordination should be re-examined, and an alternative approach based on multi-channel receivers is suggested that should be more flexible, simpler, and easier to operate than the current system.     

Recent Development and Utilization of Two-Way Satellite Time and Frequency Transfer

TWSTFT (Two Way Satellite Time and Frequency Transfer) has been developed for a long time, and has become one of the most precise and accurate techniques for comparison of the frequency standards located at remote sites. Since 1999, TWSTFT has been used in TAI (International Atomic Time) generation. More than two-thirds of TAI clocks and almost all the primary frequency standards are transferred using TWSTFT. To increase the time transfer precision and stability, several calibration methods were developed and the possible instability sources were investigated. Due to the high redundancy of the time transfer links and quick developments of independent time transfer techniques (e.g. GPS), much utilization was proposed to enhance the robustness, to reduce the uncertainty, and to reduce the diurnal effect of TWSTFT. For example, one can adopt the concept of network time transfer to improve the short term stability, or combine the data of different time transfer techniques to take their advantages. The numerical results of network time transfer are very promising. For the future development, a newly developed DPN-based TWSTFT method shows competitive performance with the GPS PPP and much less diurnals than the conventional TWSTFT. It is a very promising method for the next-generation TWSTFT. This paper will give an overview of the above topics.     

激光干涉法一次冲击加速度计动态特性校准

介绍利用激光光栅干涉技术进行冲击加速度动态特性校准的一种方法。将冲击加速度直接绝对溯源于基本量和单位(时间和长度);说明差动式光栅激光干涉冲击校准装置的原理,介绍了使用调频信号的数字化解调方法和模式识别方法实现数据处理的基本过程;最终给出了被校准的加速度计的频率特性曲线和传递函数实验结果;使用本文方法可以进行加速度计动态特性的校准测试。     

Prelaunch characterization of the Ozone Monitoring Instrument transfer function in the spectral domain

A method and an experimental measurement setup to accurately characterize the instrument transfer function in the spectral domain for hyperspectral spectrometers in the ultraviolet-visible wavelength range are described. The application to the on-ground calibration of the Ozone Monitoring Instrument (OMI) on board the Earth Observing System Aura satellite is presented and discussed. With this method and setup, based on an echelle grating, a sampling of the instrument transfer function in the spectral domain can be selected and is not limited by the spectral resolution and sampling of the spectrometer that is being characterized. The importance of accurately knowing the OMI instrument transfer functions in the spectral domain for in-flight differential optical absorption spectroscopy retrievals and wavelength calibration is discussed. The analysis of the OMI measurement data is presented and shows that the instrument transfer functions in the spectral domain as a function of wavelength and viewing angle can be determined with high accuracy.     

基于时延冗余测量的阵形校准

海底柔性水平阵的阵形校准,可以利用两个校准声源测量阵元间的声传播时延差来求解得到。传统算法只利用了相邻阵元信号测量的时延差,但误差会随噪声增大而出现累积。在信噪比降低时,所提方法通过冗余时延测量有效地减少了误差累积,从而提高了阵形校准的精度与稳定性。数值仿真与实验结果都验证了该方法的有效性。     

Two approaches to the continuous-radiation field calibration of a hydrophone in a nonanechoic water tank

A comparative analysis is carried out of a time-delay spectrometry method and a proposed method for the sliding complex weighted averaging of the frequency dependence of the transfer impedance of a radiator and receiver, which provide different approaches to the free-field continuous-radiation calibration of hydrophones in a nonanechoic water tank. The advantages of the second method are demonstrated.     

差分定位接收机动态校准

随着差分定位技术的发展,全球导航卫星系统的定位精度有了很大的提高。本文介绍了差分定位的原理,利用本实验室的标准基站,在现有静态校准的基础上,通过采用一种旋转机构,使差分定位双天线产生圆周的相对运动,从而实现对差分定位定向接收机的动态校准。     

An All-Digital Self-Calibration Method for a Vernier-Based Time-to-Digital Converter

This paper presents a new calibration method for a Vernier-based time-to-digital converter (TDC). In the proposed method, delay lines in the TDC are configured as on-chip ring oscillators for generating a sequence of time events. These time events are applied to the TDC in the calibration mode, and then, the probability distribution of output codes is determined. The variations of the quantization step and the actual transfer characteristic representing the TDC are estimated through statistical analysis of the output codes. The proposed method eliminates the need for accurate external sources typically used for TDC calibration. Simulation and experimental results using a field-programmable gate array platform indicate that the method can successfully be employed to calibrate high-resolution TDCs with reasonable accuracy.