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General

posted 9 hours 30 minutes ago
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Telecommunication

posted 3 days 1 hour ago

Satellite communication is the use of artificial satellites to provide communication links between various points on Earth. Satellite communications play a vital role in the global telecommunications system. An artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth.

Approximately 2,000 artificial satellites orbiting Earth relay analog and digital signals carrying voice, video, and data used for television, telephone, radio, internet, and military applications.

There are three types of communications satellite systems. They are categorised according to the type of orbit they follow.A geostationary satellite orbits the earth directly over the equator, approximately 22,000 miles up.

Satellite communication has two main components: 

Ground segment - which consists of fixed or mobile transmission, reception, and ancillary equipment. 

Space segment - which primarily is the satellite itself. A typical satellite link involves the transmission or uplinking of a signal from an Earth station to a satellite. 

Geostationary orbit is a circular orbit, situated directly over the equator. A satellite positioned in geostationary orbit circles at the same speed and in the same direction as the Earth rotates, meaning that it stays ‘fixed’ in relation to a point on the ground. Geostationary orbit is at an altitude of about 36,000 km, or 22,380 miles (in fact, it is exactly 35,784 km) – a distance equal to six times the radius of the Earth – with an orbital period of 23 hours 56 minutes.

Choosing frequency bands

Modern telecommunications media primarily use six frequency bands, designated by letters.

Bande

Frequency range

Applications

L

1 to 2 GHz

Mobile telephony and data transmission

S

2 to 3 GHz

Mobile telephony and data transmission

C

3.4 to 7 GHz

Fixed telephone services, radio broadcast services, business networks

X

7 to 8.4 GHz

Government or military communications, encrypted for security reasons

Ku

10.7 to 18.1 GHz

High data-rate transmission, television, videoconferencing, business networks

Ka

18.1 to 31 GHz

High data-rate transmission, television, videoconferencing, business networks

 

 Frequency bands are assigned according to standard guidelines set by the International Telecommunications Union (ITU), depending on the service to be provided, and coordination between operators must be maintained so as to avoid any interference between satellites.

 

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Telecommunication

posted 1 week 1 day ago

Disruptive technologies of tomorrow usually lack widely accepted definitions and are often invented by individual entities not necessarily responsible for formulating and enforcing industry standards that govern the technology evolution. Innovation and advancements in the field of connected technologies started with networked computers which then progressed through the Internet era and have evolved beyond the concept of connecting physical objects as part of the Internet of Things (IoT) revolution.

 

The term “Internet of Things” coined by British entrepreneur Kevin Ashton in 1999 described connectivity among physical objects and no longer holds in its original form. It is now largely overlapped, confused and even mystified with the term Internet of Everything (IoE). IoE is considered a superset of IoT and Machine-to-Machine (M2M) communication considered a subset of IoT. Let’s take a closer look into differences between IoT, IoE, and M2M, which has impacted consumers and businesses alike.

What Is the Internet of Everything (IoE)?

Although the concept of Internet of Everything emerged as a natural development of the IoT movement and is largely associated with Cisco’s tactics to initiate a new marketing domain, IoE encompasses the wider concept of connectivity from the perspective of modern connectivity technology use-cases. IoE comprises of four key elements including all sorts of connections imaginable:

People: Considered as end-nodes connected across the internet to share information and activities. Examples include social networks, health and fitness sensors, among others.

Things: Physical sensors, devices, actuators and other items generating data or receiving information from other sources. Examples include smart thermostats and gadgets.

Data: Raw data analyzed and processed into useful information to enable intelligent decisions and control mechanisms. Examples include temperature logs converted into an average number of high-temperature hours per day to evaluate room cooling requirements.

Processes: Leveraging connectivity among data, things and people to add value. Examples include the use of smart fitness devices and social networks to advertise relevant healthcare offerings to prospective customers.

IoE establishes an end-to-end ecosystem of connectivity including technologies, processes and concepts employed across all connectivity use-cases. Any further classifications – such as Internet of Humans, Internet of Digital, Industrial Internet of Things, communication technologies and the Internet itself – will eventually constitute a subset of IoE if not considered as such already.

What Is the Internet of Things (IoT)?

Devices, computers, and machines were already connected by the time Kevin Ashton coined the term Internet of Things. The concept gained steam for its ability to connect the unconnected – physical-first objects previously incapable of generating, transmitting and receiving data unless augmented or manipulated. Embedding sensors, control systems, and processors into these objects enables horizontal communication across a multi-node, open network of physical-first objects.

The term is also vaguely used to describe connected digital-first devices such as wearable gadgets that may be classified as Internet of Digital while offering the same functionality as its physical-first counterpart developed into a smart connected technology. The meaning and application of the term IoT will continue to evolve as new connected technologies emerge, replacing physical-first objects with smart connected devices and use-cases to constitute all new “Internet-of-X” classifications. 

What Is Machine to Machine (M2M)?

The aptly named IoT subset M2M initially represented closed, point-to-point communication between physical-first objects. The explosion of mobile devices and IP-based connectivity mechanisms has enabled data transmission across a system of networks. M2M is more recently referred to technologies that enable communication between machines without human intervention. Examples include telemetry, traffic control, robotics, and other applications involving device-to-device communications.

How Does This Impact Businesses and Consumers?

The concepts of IoE, IoT, and M2M are inherently subjected to the confusion surrounding limitations associated with meaning, use cases, and adoption. While there are no industry standard and regulations from appropriate governing authorities, these concepts will continue to evolve in response to technology innovation, changing consumer trends and varied marketing tactics. Business evaluating the promise and potential of connectivity offerings will, therefore, have to dig into the specifics of each situation instead of establishing conclusions based solely on the proposed labels of IoE, IoT, or M2M.

 

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Mechanical Engineering

posted 1 week 3 days ago
Environmental Radiation

Solar radiation is essential to all life on earth. Through the process of photosynthesis, solar radiation satisfies the human need for food, fiber, and fuel. Utilizing thermal and photovoltaic processes, it also has the potential to satisfy considerable demand for heat and electricity.

Together, solar radiation and radiation emitted by surfaces of the earth’s land and oceans comprise what is commonly termed environmental radiation. It is the interaction of environmental radiation with the earth’s atmosphere that determines the temperature of our planet.

Solar Radiation                  

The sun is a nearly spherical radiation source that is 1.39 × 109 m in diameter and is located 1.50 ×1011 m from the earth. As noted previously, the sun emits approximately as a blackbody at 5800 K. As the radiation emitted by the sun travels through space, the radiation flux decreases because of the greater (spherical) area through which it passes. At the outer edge of the earth’s atmosphere, the flux of solar energy has decreased by a factor of (rs/rd)2, where rsis the radius of the sun and rdis the distance from the sun to the earth.

The solar constant, Sc, is defined as the flux of solar energy incident on a surface oriented normal to the sun’s rays, at the outer edge of the earth’s atmosphere, when the earth is at its mean distance from the sun. It has a value of 1368 0.65 W/m2.



For a horizontal surface (that is, parallel to the earth’s surface), solar radiation appears as a beam of nearly parallel rays that form an angle , the zenith angle, relative to the surface normal.

The extraterrestrial solar irradiation, GS,o, defined for a horizontal surface, depends on the geographic latitude, as well as the time of day and year.

It may be determined from an expression of the form



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General

posted 2 weeks 5 days ago

Autonomous cruise control (ACC; also called adaptive cruise controlradar cruise control, or traffic-aware cruise control) is an optional cruise control system for road vehicles that automatically adjusts the vehicle speed to maintain a safe distance from vehicles ahead. It makes no use of satellite or roadside infrastructures nor of any cooperative support from other vehicles. Hence control is imposed based on sensor information from on-board sensors only. Cooperative Adaptive Cruise Control (CACC) further extends the automation of navigation by using information gathered from fixed infrastructure such as satellites and roadside beacons, or mobile infrastructure such as reflectors or transmitters on the back of other vehicles.

 

Such systems go under many different trade names according to the manufacturer. These systems use either a radar or laser sensor setup allowing the vehicle to slow when approaching another vehicle ahead and accelerate again to the preset speed when traffic allows. ACC technology is widely regarded as a key component of any future generations of intelligent cars. The impact is equally on driver safety as on economising capacity of roads by adjusting the distance between vehicles according to the conditions

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General

posted 2 weeks 5 days ago

Electrodynamic tethers (EDTs) are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy. Electric potential is generated across a conductive tether by its motion through a planet's magnetic field.

As part of a tether propulsion system, crafts can use long, strong conductors (though not all tethers are conductive) to change the orbits of spacecraft. It has the potential to make space travel significantly cheaper.[citation needed] When direct current is applied to the tether, it exerts a Lorentz force against the magnetic field, and the tether exerts a force on the vehicle. It can be used either to accelerate or brake an orbiting spacecraft.

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Telecommunication

posted 3 weeks 3 days ago
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Telecommunication

posted 3 weeks 4 days ago
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General

posted 1 month 3 days ago

  I am theoretically proposing the ideology of a 'quark' as a tetrahedral shape, being spun at an angle which would emit wave functions akin to sine, cosine and tangent. That is to say there are 3 internal waves and 3 external waves which would be more definitive, according to the trigonometric values, including cotangent, secant and cosecant. The faster the tetrahedron spins, the more density there is upon the particle and in an opposing manner with an antiparticle, there should be definite increments of density according to spin rates. This is akin to spherical 'pi', where our tetrahedral shape is the equivalent in it's spin state to the diameter of a sphere. With the antiparticle, the ideal theory would be that there are 3 internal and 3 external wave functions as well; sine-1, cosine-1, and tangent-1. The next three wave functions should be obvious; cotangent-1, secant-1 and finally, cosecant-1. With pressure internally there is less externally and vice-versa in both, the quark and anti-quark(...again, theoretically!).

   In my own study of elemental particles, I consider this terahedron to be one of three elemental particles of which the other two are a cube and a sphere. The sphere represents liquid substances, the tetrahedron represents gaseous matter and the cube represents solid matter. 

All things are off-shoots of the same three, multi-dimensional shapes. I am also rewriting the definition of a circle as; the shortest distance between two points that remain an equal and opposite distance from each other, in transit from point to point. This definition is more balanced than a point revolving around a fixed point.

   This is the bulk of my knowledge at this point and I am happy to contribute my ideas of Philosophical and Theoretical Physics as I am glad you asked for my input, thanks

davidsaari17@gmail.com

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