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Data Fusion via Kalman Filter: GPS and INS
Published in Shuzhi Sam Ge, Frank L. Lewis, Autonomous Mobile Robots, 2018
Jingrong Cheng, Yu Lu, Elmer R. Thomas, Jay A. Farrell
The GPS is designed to provide position, velocity, and time estimates to users at all times, in all weather conditions, anywhere on the Earth. The existing GPS signal for each satellite consists of a spectrum spreading code and data bits modulated onto a carrier signal. By accurately measuring the transit time of the code signal, the receiver can form a measurement of the pseudorange between the satellite and the receiver antenna. This measurement is referred to as a pseudorange as it is also affected by receiver and satellite clock errors. By processing the data bits to determine the clock error model and ephemeris data, the receiver can compute the satellite position and clock errors as a function of time. Tracking the satellite signal requires that the receiver acquire either frequency or phase lock to the satellite carrier signal. Phase information from the tracking loop has utility as an additional range measurement and the change in the phase measurement over a known period of time (referred to in the GPS literature as a Doppler measurement) can be used to estimate the receiver velocity. The GPS satellites broadcast signals on two frequencies: L1 and L2. Users with “two frequency” receivers can obtain pseudorange, phase, and Doppler measurements for each of the two frequencies.
Positioning and Tracking Approaches and Technologies
Published in Hassan A. Karimi, Advanced Location-Based Technologies and Services, 2016
Dorota Grejner-Brzezinska, Allison Kealy
Pseudorange is a geometric range between the transmitter and the receiver, distorted by the propagation media and the lack of synchronization between the satellite and the receiver clocks. It is recovered from the measured time difference between the epoch of the signal transmission and the epoch of its reception by the receiver. The actual time measurement is performed with the use of the PRN code. In principle, the receiver and the satellite generate the same PRN sequence. The arriving signal is delayed with respect to the replica generated by the receiver, as it travels ~20,000 km. In order to find how much the satellite’s signal is delayed, the receiver-replicated signal is delayed until it falls into synchronization with the incoming signal. The amount by which the receiver’s version of the signal is delayed is equal to the travel time of the satellite’s version (Figure 1.4). The travel time, Δt (~0.06 s), is converted to a range measurement by multiplying it by the speed of light, c.
Coastal Subsidence
Published in Ramesh P. Singh, Darius Bartlett, Natural Hazards, 2018
Andrea Taramelli, Ciro Manzo, Emiliana Valentini, Loreta Cornacchia
The first and widely used measuring technique adopts the signal of 24 Navigation Satellite with Time and Ranging (NAVSTAR) satellites that orbit 20 km from the Earth’s surface. These satellites transmit binary information of all parameters describing their orbit on two different frequencies (L1 and L2). The GPS measures pseudorange, the pseudodistance between a satellite and navigation satellite receiver.
GNSS Satellite Selection-based on Per-satellite Parameters Using Deep Learning
Published in IETE Journal of Research, 2022
Prateek Singh, Janamejay Joshi, Abhijit Dey, Nitin Sharma
The difference between the apparent arrival and transmission times of the GNSS signal is measured by the receiver and converted to a pseudorange measurement using a simple mathematical relation [17]: where is the true pseudorange-defined as the geometric range between the satellite and receiver , is the speed of light, is time when the signal is transmitted by the satellite and is time when signal is received by the receiver. Then, the measured pseudorange is calculated as: where is the measured pseudorange, in represents the measured pseudorange, is the clock bias of the receiver, and are the unknown receiver positions. From the navigation message or ephemerides broadcasted by the satellites, which include information on the satellite clock offset , the satellite positions are calculated.
Implementation and Analysis of Grid-Based Ionospheric Correction Technique and Positioning Errors of NavIC + GPS ARAMIS SDR Receiver
Published in IETE Technical Review, 2022
Mehul V. Desai, Darshna Jagiwala, Shweta N. Shah
Since the signal received from the antenna is affected by many intentional and unintentional error sources, the pseudorange should be corrected before the position estimation to improve the system's positioning accuracy. Among all the sources of error, the ionospheric effect is the main factor [20–22]. Therefore, we have implemented and observed the impact of various ionospheric error detection and correction techniques, such as dual-frequency correction, single-frequency Klobuchar, Grid Ionospheric Vertical Delay (GIVD) [2], Taylor Series Expansion (TSE) [21], and Multivariate Polynomial Regression (MPR) Method [22] for NavIC + GPS. The impacts of unintentional interference [23] and intentional interference (Jamming) [24] is available.
A Comprehensive Survey on GNSS Interferences and the Application of Neural Networks for Anti-jamming
Published in IETE Journal of Research, 2021
Kambham Jacob Silva Lorraine, Madhu Ramarakula
Receiver noise: Error in the pseudo-range measurement can be caused due to the noise produced by the components of the receiver and due to the antenna pickup of electromagnetic radiation from the sky and also from other sources that are surrounding the antenna. It causes an error of nearly 1.5 m for the Standard Positioning System (SPS) users.