Questions tagged [gnss]
Questions about Global Navigation Satellite Systems (GNSS), such as existing Global Positioning System (GPS) and GLObal NAvigation Satellite System (GLONASS), but also future such systems in development, like European Galileo, China's Compass or India's IRNSS (Indian Regional Navigational Satellite System).
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What does "Common frequency offset" plot means in gnss raw measurements?
I'm using Google's MATLAB code to analyze raw gnss measurement made with gnsslogger android app. In plots, there is one in particular that I don't understand the meaning, which is "Common ...
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Extract GPS navigation messages from a RINEX navigation file
As a hobby project, I want to implement methods from the "GPS Software Attack" paper, which involves modifying GPS navigation messages.
With this goal in mind, I am looking for:
Examples of ...
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Is there an authoritative source for which GNSS satellite transmits which signals?
I'm trying to algorithmically predict which signals from which GNSS satellites could be heard by a ground-based receiver (without actually looking at the recieved data; the idea is to be able to also ...
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Calculating the elevation and azimuth angles of satellites with location information obtained from sp3 ephemeris files
I'm trying to calculate elevation and azimuth angles of a satellite for a ground GPS receiver. I downloaded the SP3 file for the day '12-01-2015'. The ephemeris files are in the link below.
https://...
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How to download (Assisted GPS) AGPS file on PC?
I am trying to implement GPS receiver in software. Can I use AGPS file for faster locking of GPS satellites? I read somewhere that EPO files exist for Assisted GPS but I can't find any place to ...
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Dilution of precision in different coordinates
Given the ranges $\rho^{(s)}_{R_x}=\sqrt{(x_{R_x}-X^{(s)})^2+(y_{R_x}-Y^{(s)})^2+(z_{R_x}-Z^{(s)})^2}$ between a receiver $R_x$ and an $s$-th satellite, where $s=1, 2, ... n$, one can construct the ...
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How to calculate the ECEF coordinates of a satellite given its elevation and azimuth angle, plus the coordinates of a reference object on Earth
So I am looking for a way to 'reverse engineer' satellite ECEF coordinates given its angles of elevation and azimuth and given the coordinates of an object on Earth serving as a reference ground. The ...
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Time parameters in RINEX navigation file
Currently, I am trying to determine the position of a GPS satellite from a RINEX navigation file. I am using RINEX 2.11. Tables A3 and A4 describe how navigation files are structured.
In order to ...
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Understanding "classical" algorithms behind RINEX files post-processing
I'm new to this site so I want to apologize beforehand for all the mistakes I could make while writing this.
So just to put my situation into context : I am currently an intern in an AI company tasked ...
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Which is more accurate, the ellipsoidal height from SLR or GNSS?
Satellite Laser Ranging (SLR) and Global Navigation Satellite System (GNSS) both measure the ellipsoidal heights. Which measurement of ellipsoidal height is more accurate?
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What is the difference between SBAS and PPP used in GNSS accuracy corrections?
I've found that Satellite Based Augmentation System uses reference stations to compute a model for correction and send them via a master station to a geosynchronous satellite, then to GPS receiver.
I ...
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What is "Time To First Fix" in GNSS?
I used an app to test GPS, that shows me TTFF is equal to a few seconds.
I want to understand :
What is Time To First Fix?
Is having internet access useful to improve it?
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Is Satellite Based Augmentation System ,used in GPS, a Differential Technique?
I've read that to get a higher accuracies in GPS, we use differential positioning techniques which compute for satellites errors, using well-known position base station.
I want to know if the ...
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Does using multifrequencies totally eliminate the ionosphere delay on GPS measurements?
I've read that the GPS receiver computes the difference in measurement for two GPS satellite signals (in two frequencies L1 and L2), in order to compute the actual delay that the ionosphere causes.
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Why does GPS need the fourth satellite?
I am currently working on a GPS project, so I am doing some research about the subject. I understand that the GPS receiver knows its location by calculating its distances from 3 satellites, and by ...