Near-real time synchronization through a network of GNSS receivers located in timing laboratories

2010 ◽  
Author(s):  
Giancarlo Cerretto ◽  
Andrea Perucca ◽  
Patrizia Tavella ◽  
Ricardo Piriz
Keyword(s):  
Real Time ◽  
Time Synchronization ◽  
Gnss Receivers

Priority inheritance protocols: an approach to real-time synchronization

1990 ◽  
Vol 39 (9) ◽  
pp. 1175-1185 ◽  
Author(s):  
L. Sha ◽  
R. Rajkumar ◽  
J.P. Lehoczky
Keyword(s):  
Real Time ◽  
Time Synchronization

Real-time and near real-time ZTD from a local network of low-cost dual-frequency GNSS receivers.

2021 ◽  
Author(s):  
Tomasz Hadas ◽  
Grzegorz Marut ◽  
Jan Kapłon ◽  
Witold Rohm
Keyword(s):  
Water Vapor ◽  
Real Time ◽  
Low Cost ◽  
Weather Prediction ◽  
Local Network ◽  
System Component ◽  
Dual Frequency ◽  
Lower Accuracy ◽  
Gnss Receivers ◽  
The Impact

<p>The dynamics of water vapor distribution in the troposphere, measured with Global Navigation Satellite Systems (GNSS), is a subject of weather research and climate studies. With GNSS, remote sensing of the troposphere in Europe is performed continuously and operationally under the E-GVAP (http://egvap.dmi.dk/) program with more than 2000 permanent stations. These data are one of the assimilation system component of mesoscale weather prediction models (10 km scale) for many nations across Europe. However, advancing precise local forecasts for severe weather requires high resolution models and observing system.   Further densification of the tracking network, e.g. in urban or mountain areas, will be costly when considering geodetic-grade equipment. However, the rapid development of GNSS-based applications results in a dynamic release of mass-market GNSS receivers. It has been demonstrated that post-processing of GPS-data from a dual-frequency low-cost receiver allows retrieving ZTD with high accuracy. Although low-cost receivers are a promising solution to the problem of densifying GNSS networks for water vapor monitoring, there are still some technological limitations and they require further development and calibration.</p><p>We have developed a low-cost GNSS station, dedicated to real-time GNSS meteorology, which provides GPS, GLONASS and Galileo dual-frequency observations either in RINEX v3.04 format or via RTCM v3.3 stream, with either Ethernet or GSM data transmission. The first two units are deployed in a close vicinity of permanent station WROC, which belongs to the International GNSS Service (IGS) network. Therefore, we compare results from real-time and near real-time processing of GNSS observations from a low-cost unit with IGS Final products. We also investigate the impact of replacing a standard patch antenna with an inexpensive survey-grade antenna. Finally, we deploy a local network of low-cost receivers in and around the city of Wroclaw, Poland, in order to analyze the dynamics of troposphere delay at a very high spatial resolution.</p><p>As a measure of accuracy, we use the standard deviation of ZTD differences between estimated ZTD and IGS Final product. For the near real-time mode, that accuracy is 5 mm and 6 mm, for single- (L1) and dual-frequency (L1/L5,E5b) solution, respectively. Lower accuracy of the dual-frequency relative solution we justify by the missing antenna phase center correction model for L5 and E5b frequencies. With the real-time Precise Point Positioning technique, we estimate ZTD with the accuracy of 7.5 – 8.6 mm. After antenna replacement, the accuracy is improved almost by a factor of 2 (to 4.1 mm), which is close to the 3.1 mm accuracy which we obtain in real-time using data from the WROC station.</p>

Accumulative Drifting Model of Inertial Navigation Platform under Elliptic Vibration

2014 ◽  
Vol 613 ◽  
pp. 269-278
Author(s):  
Zhen Xian Fu ◽  
Yu Rong Lin ◽  
Yang Liu ◽  
Xing Lin Chen
Keyword(s):  
Real Time ◽  
Time Synchronization ◽  
Inertial Navigation ◽  
Parameter Calibration ◽  
Testing Environment ◽  
Drift Model ◽  
General Elliptic ◽  
Elliptic Vibration ◽  
Proposed Model ◽  
Error Parameter

To facilitate the calibration of a precision inertial navigation platform, the drifting of the platform under vibratory testing environment is analyzed, and a simplified drift model is developed which features the accumulative rather than instantaneous impact of the vibration on the platform drifting. When applied to error parameter calibration for the platform, the proposed model entails much less computing load in drifting prediction, and removes the requirement of strict real-time synchronization between the vibration generating device and the drift-predicting programs. The form of vibration can be assumed to be elliptic, a relatively general one which allows the shaker to vibrate sinuoidally in two directions perpendicular to each other and with phase difference of 90 degree. Under certain circumstances, the elliptic vibration can be simplified to a linear or circular one, as is typical in practice. Simulations of the platform drifting error under linear, circular and general elliptic vibration shows that the accumulative model can well serve as an alternative to the conventional one in such test environments, and the merits of the proposed model become more prominent when the frequency of vibration gets higher.

An Information Real-Time Transmission Algorithm Based on the Android Platform

2014 ◽  
Vol 701-702 ◽  
pp. 943-946
Author(s):  
Nian Fang Hong
Keyword(s):  
Real Time ◽  
Data Transmission ◽  
Cell Phone ◽  
Streaming Media ◽  
Time Synchronization ◽  
Adaptive Streaming ◽  
Time Increase ◽  
Limited Bandwidth ◽  
Real Time Transmission ◽  
Media Data

In the wireless network environment, a large number of applications based on cell phone have emerged. But it has appeared some problems such as large amount of data and limited bandwidth and higher quality transmission in the mobile streaming media data transmission. To solve these problems, this paper designs a bandwidth adaptive streaming media real-time synchronization algorithm. Algorithm firstly analysis the state of the network, and then through real-time increase or decrease the factor method to effectively adjust the code flow rate, thus improve the QoS of streaming in transmission; to meet the learners' online learning, for subsequent teaching and interaction provides a good technical support.

Real-Time Measurement Method of Doppler Based on GPS Carrier Signals

2012 ◽  
Vol 226-228 ◽  
pp. 2050-2055 ◽  
Author(s):  
Shao Feng Dong ◽  
Bao Qiang Du ◽  
Wei Zhou
Keyword(s):  
Frequency Shift ◽  
Real Time ◽  
Measurement Method ◽  
Dynamic Range ◽  
Time Synchronization ◽  
Influencing Factor ◽  
Doppler Frequency ◽  
Time Measurement ◽  
Time Frequency ◽  
Real Time Measurement

According to Doppler effect of satellite on the time synchronization technology between satellite and the ground station, a real-time measurement method of Doppler is proposed based on GPS carrier signals. Using Doppler observations from GPS receiver, the method can real-timely measure Doppler frequency shift of GPS including dynamic Doppler and media Doppler whose error can be timely modified in the receiver end. Simulation results show that the frequency shift caused by dynamic Doppler, a main influencing factor in the course of transmission of time-frequency signal by GPS satellite, is between plus or minus several thousands Hz. Comparing to traditional measurement method of Doppler, the method makes it possible to fast track phase of signal in large dynamic range in synchronous technology.

Real time numerical dynamic orbit determination of geostationary satellite for time synchronization service

2003 ◽  
Vol 7 (5) ◽  
pp. 385-395 ◽  
Author(s):  
Bang-Yeop Kim ◽  
Jae-Cheol Yoon ◽  
Kyu-Hong Choi ◽  
Young-Keun Chang
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Time Synchronization ◽  
Geostationary Satellite

LXI Precision Time Protocol Applied Research

2013 ◽  
Vol 330 ◽  
pp. 561-564 ◽  
Author(s):  
Ming Li ◽  
Chun Ping Wang ◽  
Zhi Qiang Wang
Keyword(s):  
Real Time ◽  
Applied Research ◽  
Time Synchronization ◽  
Local Area Network ◽  
Local Area ◽  
Test System ◽  
Area Network ◽  
Automatic Test System ◽  
Precision Time ◽  
Precise Time

In order to meet the real-time demands of some equipment networked test, the time synchronization techniques of ATS based traditional instrument buses are compared with the techniques of LXI ATS. Accordingly，the necessity of LXI ATS time synchronization technique study is put forward. The sorts of time synchronization techniques based on Local Area Network are analyzed. In addition, some methods which could improve the level of LXI data real-time communications are presented. Afterwards, technique realizations of PTP are studied in detail. Local Area Network techniques and IEEE 1588 Precise Time Protocol are adopted in the LXI Automatic Test System which designed in the paper, and the level of time synchronization precision in the system is improved.

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