Geophysical MASINT (Measurement and Signature Intelligence) refers to a sub-discipline of MASINT that is focused on collecting and analyzing geophysical data to gather intelligence. This type of intelligence can involve the measurement of various physical phenomena that provide insights into activities, movements, or characteristics of entities within the Earth’s environment.
Gradient pattern analysis is a technique often used in various fields such as image processing, computer vision, and machine learning, particularly for the purpose of analyzing and extracting features from data that exhibit gradients, such as images or spatial data. Here’s a breakdown of what this concept generally involves: ### Key Concepts 1. **Gradient**: In the context of images, the gradient of an image is a directional change in the intensity or color.
Group delay and phase delay are concepts used in signal processing and communications to analyze how different frequency components of a signal are handled by a system, particularly in the context of filters and communication channels. ### Phase Delay **Definition**: Phase delay refers to the time delay experienced by a specific frequency component of a signal due to the phase shift introduced by a system.
In electronics, "half-time" generally refers to the time required for the voltage across a capacitor to decay to half of its initial value during discharge, or for a signal to reach half of its maximum value in certain contexts. It is a concept often associated with the behavior of capacitors in RC (resistor-capacitor) circuits. **1. Capacitor Discharge:** When a charged capacitor discharges through a resistor, the voltage across the capacitor decreases exponentially.
The Hann function, also known as the Hann window or Hann taper, is a type of window function used in signal processing to reduce spectral leakage when performing a Fourier transform on a finite-length signal. The Hann window is particularly useful in applications such as audio signal processing, vibration analysis, and other fields that require frequency analysis of signals. The mathematical expression for the Hann window function is defined as follows: \[ w(n) = 0.
Heterodyne is a technique used in various fields, most notably in communications and signal processing, to convert a signal from one frequency to another. The fundamental principle behind heterodyning involves mixing two different frequencies to produce new frequencies, specifically the sum and difference of the original frequencies. ### Key Concepts of Heterodyne: 1. **Mixing Frequencies**: Heterodyne systems typically involve a local oscillator that generates a signal at a specific frequency.
The Hexagonal Efficient Coordinate System (HECS) is a spatial coordinate system that utilizes hexagonal grids for representing data in two-dimensional space. It is designed to optimize various attributes, such as efficiency in spatial representation, distance calculation, and neighbor identification, compared to traditional square grids. ### Key Features of HECS: 1. **Hexagonal Grids**: In a hexagonal grid, each cell is a hexagon, which allows for better packing of cells in a plane compared to squares.
The Higher-order sinusoidal input describing function is a concept from control theory and nonlinear systems analysis. It extends the idea of the describing function, which is a method used to analyze nonlinear systems using harmonic balance. The basic idea behind the describing function is that a nonlinear system's response to sinusoidal inputs can be approximated in the frequency domain.
Hilbert spectral analysis is a technique used primarily in the fields of time series analysis and signal processing to analyze non-linear and non-stationary signals. This method combines the Hilbert transform with the concept of empirical mode decomposition (EMD) to provide a time-frequency representation of a signal. ### Key Components: 1. **Hilbert Transform**: The Hilbert transform is a mathematical operation that, when applied to a real-valued signal, produces an analytic signal.
Hilbert spectroscopy is a method used to analyze complex signals or spectra, particularly in the context of identifying and characterizing materials and their properties. The technique utilizes concepts from Hilbert space and transforms to decompose signals into their constituent parts, allowing for the extraction of specific features from the data.
The Hilbert spectrum is a tool used in signal processing and time series analysis that provides a way to analyze non-linear and non-stationary signals. It is derived from the Hilbert transform, which can be applied to a signal to create an analytic representation. The Hilbert transform allows the extraction of instantaneous frequency and amplitude from a signal, creating a time-dependent representation that can reveal information about the signal's frequency content over time.
The Hilbert transform is a mathematical operation that takes a real-valued function and produces a related complex-valued function. It is widely used in signal processing, communication theory, and various fields of applied mathematics. The transform is particularly useful for analyzing signals and extracting their phase and amplitude characteristics.
The Hilbert–Huang Transform (HHT) is a method of signal processing that is designed for analyzing nonlinear and non-stationary signals. It comprises two main components: the Empirical Mode Decomposition (EMD) and the Hilbert Transform. ### Components of HHT 1. **Empirical Mode Decomposition (EMD)**: - EMD is an adaptive data analysis technique that decomposes a signal into a finite number of intrinsic mode functions (IMFs).
Homomorphic filtering is a signal processing technique used primarily in image enhancement. The main idea behind homomorphic filtering is to separate an image into its illumination and reflectance components, allowing for the manipulation of these components separately to improve image quality. ### How it Works: 1. **Logarithmic Transformation**: The first step in homomorphic filtering involves taking the logarithm of the image intensity values. This transformation effectively linearizes the multiplicative relationship between the illumination and reflectance in the image.
In-phase and quadrature components are concepts commonly used in signal processing and telecommunications, particularly in the context of complex signals and modulation techniques. They allow for the effective representation and manipulation of signals in both analog and digital forms. 1. **In-Phase Component (I)**: This is the part of a signal that is aligned with the reference signal (often a cosine wave). It represents the component of the signal that follows the same phase as the reference.
The Itakura–Saito distance is a measure used primarily in the context of signal processing and speech recognition to quantify the difference between two probability density functions (PDFs) or spectrograms. It is particularly useful for analyzing audio signals, as it provides a way to measure the distortion between two signals in a way that is more consistent with human perception than some other distance measures.
Kernel-phase refers to a method used in the analysis of interferometric data, particularly in the context of astrophysics and astronomy. It is often employed in the study of exoplanets and the characterization of astronomical objects with instruments like the Very Large Telescope Interferometer (VLTI) and others. The main idea behind kernel-phase is to analyze the phase information of interferometric data rather than relying solely on the intensity.
Lanczos resampling is a mathematical technique used in digital image processing for resizing images. It utilizes the Lanczos kernel, which is based on sinc functions, to perform interpolation when changing the dimensions of an image—either upscaling or downscaling.