GNSS

Circular buffer for real-time applications with equal input and output data rate

In this post, we will discuss two types of real-time processing applied to global navigation satellite system (GNSS) signal processing. In addition, we will discuss a circular buffering system for real-time applications with equal data rate of input and output.

Metrology

Manufacturing and space: Multilateration using ranging signals for large scale dimensional metrology

Multilateration is a position determination method that is locating an object by accurately computing the distance between the object and three or more other objects (e.g., transmitter or laser tracker) with known positions. This method is also known as hyperbolic position determination.

GNSS

TUTORIAL on how to measure RF receiver noise: A practical approach

In this post, we will provide tutorial on how to quantify a receiver (instrument) noise. In addition, the basics of various unit of measurements related to signal processing will be discussed.

GNSS

GNSS signal tracking: The need for both PLL and DLL tracking

In this post, we briefly show what PLL and DLL are, why they need to be both implemented and the effect when we only use either PLL or DLL tracking loops.

GNSS

Brief discussions on uncertainty contributors of GNSS-based positioning (Part 4)

Satellite orbit, the last main components required to calculate GNSS-based positioning, will be discussed in this post as well as the uncertainty contributors that are relevant to the satellite orbit estimation.

GNSS

Brief discussions on uncertainty contributors of GNSS-based positioning (Part 3)

Pseudorange is the distance between a global navigation satellite system (GNSS) satellite and a receiver when the offset of the receiver clock (with respect to GNSS timeline) is not yet corrected.

GNSS

Brief discussions on uncertainty contributors of GNSS-based positioning (Part 2)

In this post, we will start from the highest view of how we can estimate a position from at least four GNSS satellite ranging signals.

GNSS

Brief discussions on uncertainty contributors of GNSS-based positioning (Part 1)

In this blog series, we will discuss about uncertainty contributors on GNSS positioning and open a way to estimate the uncertainty for reliable positioning.

GNSS

TUTORIAL: Interacting with Movella XSense IMU sensor in C++

Inertial measurement unit (IMU) sensor is important for global navigation satellite system (GNSS) based positioning, velocity and timing (PNT) solutions.

GNSS

Real-time decoding of NAV messages of Septentrio receiver in C programming language

Septentrio receiver is one of the most used global navigation satellite systems (GNSS) receivers, including u-blox and Novatel GNSS receivers.

GNSS

Reading raw binary IQ data in C/C++ with malloc() and pointer

Digital signal processing (DSP) of radio frequency (RF) data very often deals with read from and write to a binary file with IQ format.

GNSS

The importance of GNSS satellite clock-bias and orbit correction

The position of a receiver calculated from global navigation satellite system (GNSS) signals is significantly affected by the accuracy of the satellite clock-bias and orbit transmitted by GNSS satellites.

GNSS

Correlator outputs for clean and spoofed GPS L1 C/A signals

The pseudorange and navigation data determination from global navigation satellite system (GNSS) signals are calculated from the correlator outputs at the tracking stage of the GNSS signal processing.

GNSS

Public datasets for spoofing and evil waveform (EWF) signals

Spoofing attacks on GNSS signals become more serious than ever due to the advancement of spoofing algorithms and computational capabilities and processing. These spoofing attacks transmit a counterfeit signal that leads to a wrong positioning, timing and navigation (PNT) solutions.

GNSS

Post-correlation Carrier to Noise Density (C/N0) calculation in GNSS signal processing

Carrier to Noise Density (C/N0) is one of instrumental metrics for GNSS receiver and signal processing. In this post, C/N0 is calculated at the post-correlation stage (signal tracking) in the GNSS signal processing stage [1].

Applied programming

The problem of writing high-digit numbers into a file and its solution

In this post, the problem of writing a real number with high digit to a file in scientific and numerical computing is presented and discussed.

GNSS

Evil waveform (EWF) in global navigation satellite system (GNSS) signal

In this post, we will discuss one of GNSS threats, that is evil waveform. Unlike jamming and spoofing, evil waveform is not a type of signal interference in GNSS signals. Instead, evil waveform is a faulty signal transmitted by a real GNSS satellite.

GNSS

The difference between C/N0 and SNR in GNSS signal processing

In signal processing, especially in global navigation satellite system (GNSS), the term signal-to-noise ratio (SNR) and carrier-to-noise density (C/N0) are very fundamental in every analysis aspect.

Applied programming

Vectorising linear sequence search in MATLAB programming

To significantly speed up the computation speed in MATLAB, the reduction of for loop should be minimised.

GNSS

Meaconing: the most common type of GNSS spoofing interference attacks

Spoofing attack is a radio frequency (RF) signal interference attack that aims to deceive a global navigation satellite system (GNSS) receiver, such as GPS or GALILEO receiver, so that the receiver track and demodulate the spoofing signals, leading to invalid position, velocity and timing solutions.

GNSS

GNSS signal modelling considering channel impairments and spoofing interferences

Signals of global navigation satellite system (GNSS), such as the well-known GPS and GALILEO, are significantly affected by channel impairments and signal interferences.

GNSS

Low frequency radio navigation system for use in natural disaster situations

It is critical to have a navigation system for search and rescue of victims and important assets in a disaster situation.

GNSS

Channel coding theory: An introduction and comparison of block, Convolutional, Turbo and low-density parity-check (LDPC) codes

In this post, a brief introduction about channel coding theory is presented. The comparison of convolutional, TURBO and LDPC codes for use in global navigation satellite system (GNSS) signals is also presented.

GNSS

GNSS spoofing: a fatal attack on GNSS system that is difficult to detect

Global navigation satellite system (GNSS), such as the infamous global positioning system (GPS), can provide position, velocity and timing (PNT) solutions in global scale and is mostly free to use by people with, for example, a smartphone at hand or any low-cost GNSS receiver.

Applied programming

Common problems in numerical computation: from data overflow, rounding error, poor conditioning to memory leak

In many modern science and engineering fields, numerical computation has an essential role to perform meaningful analyses. In numerical computation, many unexpected results occur due to errors related to digital computation instead of errors due to logic or model or formula errors.