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A new time and frequency transfer system compatible with BDS has been developed at NIM, and two of them are in operation at the BIPM since Jan 2017. Experiments with this equipment have been implemented to characterize the time and frequency transfer by BDS. This includes analysis of the satellites signal coverage statistics in the BIPM area, the error correction, the measurement noise of the NIM...
This paper considers the problem of tracking a mobile receiver using signals of Low Earth Orbit (LEO) satellites. Based on Time-Difference of Arrival (TDOA) and Frequency-Difference of Arrival (FDOA), we joint the time synchronization and localization together with a static reference anchor, which has unknown position. In this scenario, the satellites is asynchronous. Considering the time- and frequency-...
Interference detection and mitigation are important issues to guarantee the availability and service continuity of Global Navigation Satellite Systems. In this paper, a new method based on a joint spectral and time-frequency (TF) analysis is proposed for jamming excision. It localizes the time-varying energy spectral density of the interfering signal by using the S-transform, then employs a binary...
In source localization system, micro and nano satellites are often used as distributed network to complete the task. This paper proposed a rotating triangular tethered satellite formation which has fewer station maintenance costs and superior reliability to maintain the geometry. Likewise, it can achieve high-resolution localization accuracy with short baseline resulted from rotating itself. In this...
Modern vehicles incorporate dozens of sensors to provide vital sensor data to the system, where GNSS (global satellite navigation system) gives the localization, navigation, and time synchronization that can improve the safety factor of the vehicles. However, the GNSS signal is very vulnerable to jamming especially spoofing attacks that have great influence on safety and financially critical applications...
Delay-multiply acquisition method is a well known acquisition method but is seldom used in ground GNSS receivers for the sensitivity loss introduced by the multiplication step. As to space-borne GNSS receivers, doppler offset may extend to tens of kHz due to rapid movement of space vehicles at a speed near the first cosmic velocity, which makes delay- multiply acquisition method a prior candidate...
Last year the zero-baseline common-view test using BeiDou Navigation Satellite system (BDS) is done in BIRMM and the result is better than 5 ns. In this year, we have developed our own GPS/BD common view time and frequency transfer receiver. Using this receiver we carried out two remote common view experiments in BIRM-SIMT link and BIRM-NTSC link, separately. Besides, we took out TWSTFT experiment...
The precision of two-way satellite time and frequency transfer (TWSTFT) is currently limited due to instabilities of signal arrival time. We use a software-defined receiver to measure the arrival time of code signal transmitted by SATRE modem. The SDR systems have been successfully installed and performed at TL, NICT and KRISS. The SDR results show excellent suppression on the diurnals. For data of...
The purpose of this paper is to reduce the time that the receiver device takes to find the transmission frequency for the initial channel setting of receiving devices such as Digital TV which uses satellite broadcast. We propose two search algorithms based on the frequency allocation information of the transmission frequency of SCRs (Satellite Channel Routers) device. For all frequency combinations...
Global satellite navigation system (GNSS) is the most commonly used navigation and positioning system for its superior performance and low cost of the terminal receiver. However, in some scenarios, when the navigation signal is obscured or interfered, GNSS may lose its superior performance, even becomes unusable. Extending the integration time is a general way to enhance the receivers' usability....
With the operation of BD satellite navigation system, the remote time distribute based on BD satellite become possible. A remote time frequency distribute system based on the BD satellite common-view time comparison in National Time Service Center (NTSC) is constructed and implemented. The underlying system comprised with primary terminal, delivery terminal and data processing center, is able to recover...
The capability of one-way time service as an important index of satellite navigation system reflects the ability that a satellite navigation system broadcasts the system time to the clients. In this paper, the performance evaluation method of BD one-way time service is designed standing in the clients' position. The UTC(NTSC)-BDT result via Space signal reception method is obtained in NTSC, the performance...
Global Positioning System (GPS) carrier-phase (CP) time transfer, as a widely accepted high-precision time transfer method, frequently shows a data-batch boundary discontinuity of up to 1 ns, because of the inconsistency of the phase ambiguities between two consecutive data batches. To eliminate the data-batch boundary discontinuity, several techniques have been proposed in recent years. The question...
In GNSS data reduction, carrier phase (phase) and pseudorange (code) data are complementary. An illustrative example of their interplay is provided, and then it is shown that frequency biases in phase data can be estimated by examination of the difference between the code and phase residuals in Precise Point Positioning (PPP) solutions. Apparent frequency biases, in some cases approaching 0.2 ns/day...
With the development of BeiDou(BD) Navigation Satellite system, BD can be another choice for remote precise time and frequency transfer. A strict common view test using BD Navigation Satellite System is carried out in this paper. Since there are GEO, IGSO and MEO satellites in BD Navigation Satellite system, common view based on GEO, IGSO and MEO are discussed in this paper separately. Finally, we...
A GPS acquisition system which achieves extremely short search times is presented. The system requires no prior knowledge of position or time. Using a 50 MHz clock frequency, 25 satellites can be searched in parallel. The acquisition system has been implemented in 0.35 um CMOS process. Under nominal signal conditions, 2 second total search times have been demonstrated. The acquisition unit performance...
This work presents a time-frequency signal analysis framework for the modeling and simulation of GNSS-based environmental surveillance monitoring (ESM) applications. The framework is based on an enhanced version of SIRLAB, a signal representation framework developed for the analysis of environmental acoustic signals. This new time-frequency signal analysis framework has been successfully used in the...
In this paper, we propose a new generation of time and frequency transfer system using Global Navigation Satellite System (GNSS) dual frequency receiver for the purpose of both time and frequency synchronization. The system can be used as a timing source, remote time and frequency calibration, and to monitor the characteristic of the telecommunication primary reference clocks (PRC). A series of experiments...
This paper describes the determination of ionospheric and tropospheric effects on satellite communications between Inmetro ground station and GPS constellation satellites This is made with the use of a geodesic receiver to collect data and with post processing softwares for PPP implementations. The data satellite communication link is used for time and frequency maintenance of Local Time Scale UTC...
GPS/GLONASS Common view, all in view and PPP Time Transfer technology are widely used in the remote time comparison. With the benefit of the high precise measurement on carrier phase, the PPP time transfer technology which based on the carrier phase data has been used in the International time comparison for TAI computation. In this Paper, The Carrier Phase Time Transfer on BeiDou Navigation satellite...
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