Peng XiaomingInstitute for Infocomm Research, Singapore New Satellite Technologies and Applications The rapid advancement of space technology and new approaches has resulted in the miniaturizing of the size and weight of the satellites. Satellites that weigh less than kg such as micro-satellites and nano-satellites have been very actively researched and developed by both the industry and university in recent years. Various applications such as communication, navigation, climate study, remote sensing and scientific experiment have been reported.
The orbit is designed to be a terminator orbit, so that the local time at the nadir point is always either approximately sunset or sunrise. Figure shows the variation in path length as a function of elevation when the spacecraft is above the local horizon.
The path loss due to range is defined by the equation This can be derived through the following: The power density in watts per square meter of an isotropic radiator is given by where r is the radius in meters of the sphere surrounding the isotropic radiator and pt is the transmitter power.
All power emitted by that isotropic radiator will be distributed equally on the surface of the sphere.
If you’ve been paying attention to my Twitter account lately, you’ve probably noticed one or two teasers of what I’ve been working on — a Python framework/package to rapidly construct object detectors using Histogram of Oriented Gradients and Linear Support Vector Machines.. Honestly, I really can’t stand using the Haar cascade classifiers provided by OpenCV (i.e. the Viola-Jones. The ultimate list of cell phone spy apps will help caring parents around the world choose the most reliable and effective way to monitor their kids’ activities. Industry experts have analyzed the performance of different monitoring tools as well as customer’s feedback to offer the best software. The Thesis Committee for Manjunath Narayana certiﬂes that this is the approved version of the following thesis: Automatic Tracking of Moving Objects in Video.
A receiving antenna located on the surface of that sphere intercepts total power equal to the power density multiplied by the surface area of the receiving antenna as follows: It can also be shown that a transmitting antenna of effective area At which concentrates its gain within a small solid angle has an on-axis gain of where l is the wavelength of the radiation.
The receiving antenna has a gain too. Multiplying we get and this reduces to The distance and frequency-dependent term in the previous equation is the free-space path loss. Inverting it and taking the log generates the path loss equation on the previous page. The Doppler frequency shift due to the spacecraft - CGS relative motion is derived first by determining the included angle between the spacecraft velocity vector and the spacecraft - CGS orientation vector.
With this angle information, it is a simple thing to calculate the portion of that velocity vector that is parallel to the spacecraft - CGS vector and thus calculate the Doppler shift.
Due to geometry, these beams intersect the earth at approximate angles of Neglecting atmospheric losses, there is less than a 0. Path Loss Variation Due to Atmospheric Effects The Earth's atmosphere varies strongly in temperature, density and composition as a function of altitude.
The primary classification of the regions of the atmosphere is according to the temperature gradient.
Radio waves that travel from space to earth encounter four distinct regions. The first region is outer space itself; the next lower is the ionosphere, next lower is the stratosphere, and finally, where we all live and where all weather exists, the troposphere.
Each layer has characteristics that affect the propagation of radio waves. For our purposes, outer space provides lossless radio wave transmission.
The ionosphere exists from to km above the ground. Here the pressure is low enough that the ultraviolet radiation that impinges on the earth from the sun causes a thin plasma to form as it separates electrons from atoms and molecules. These free electrons can affect a radio wave through effects such as Faraday rotation, reflection and absorption.
The stratosphere resides between about 15 km and 60 km. The atmosphere contained in this region is low density and very dry.The Driver is Perspectives. Perspectives is the process that helps INTJ’s watch their own minds form patterns, get inside the minds of others and allows them to see implications far into the future.
Localization, mapping and moving object tracking serve as the basis for scene understanding, which is a key prerequisite for making a robot truly autonomous. Simultaneous localization, mapping and moving object tracking (SLAMMOT) involves not only simultaneous localization and mapping (SLAM) in dynamic environments but also detecting and tracking .
Moving object detection and tracking (D&T) are important steps in object recognition, context analysis and indexing processes for visual surveillance systems etc.. It is a big challenge for researchers to prepare algorithms on which detection and tracking is more suitable for background situation, environment conditions and to determine how.
The resulting whale tracking algorithm performs object recognition using a pixel-level classifier and domain knowledge. We find that image hue and saturation values are suitable invariants to segment whales from other elements in the scene and can be used to estimate the centroid of the moving target.
(ed note: this is a commentary about the computer game Children of a Dead Earth). I see a lot of misconceptions about space in general, and space warfare in . There are three very serious problems with the orbiting mechanism of the space machines said to whiz around the Earth.
These need to be incorporated within our “reality framework” to help us determine what is actually real and what is marketing.