What is a satellite?

A satellite can surround the earth on two basic types of orbits. The first and most obvious is a circular orbit at that distance from the Earth remains constant. The second type of orbit is elliptical orbit. When a satellite orbiting the Earth orbit is circular or elliptical, describes a plan.

It passes through geocenter. The rotation around the Earth also has two variants. It can be in the same direction as the Earth’s rotation, in which case it is said to be direct or reverse rotation of the Earth, in which case it is said to be retrograde. Speed is an important factor. For a circular orbit it is always the same. For an elliptical orbit this is no longer true because speed changes depending on the position in orbit.

Speed is an important factor. For a circular orbit it is always the same. For an elliptical orbit this is no longer true because speed changes depending on the position in orbit. Speed is highest when the moon is closest to Earth and must defeat gravity is the largest and highest minimum remoteness from Earth. For an elliptical orbit Earth’s center is in one of the foci of the ellipse.

A satellite can rotate around the Earth in different planes. The angle of inclination of the orbit is the angle between a line perpendicular to the right orbit and passing through Earth’s poles. This means that an orbit that is located in the equatorial plane has an inclination of 0 ° or 180 °, and one passing over the poles would have a slope of 90 °. Those seeking orbits over the equator are called equatorial orbits, and that passing over the poles are called polar orbits.
Another important factor on the position of the satellite elevation angle.

This is important because it can communicate with the satellite earth station when it has direct visibility to it. The elevation angle is the angle at which the satellite appears to the horizontal. If the angle is too small, the signals can be masked by objects surrounding the antenna is placed high enough. For the satellite to be used for communication earth station must be able to follow to receive signals and transmit to him. Obviously, communication will be possible only when there is direct visibility and, depending on orbit, visibility may exist only for a short period of time.

However, switching from one satellite to another introduce more complexity into the system, as well as the need for and the launch of 3 satellites. The most common option is to launch a satellite in a geostationary orbit. Using this orbit, the satellite rotates in the same direction as Earth and has a rotation period of 24 hours. As a result, he remains in the same position relative to Earth. Because the forces involved to balance and satellite remain in a geosynchronous orbit, it must turn over the equator at an altitude of 35 860 km.
Geostationary orbits are used, because once the earth station satellite was oriented, it can remain in the same position and normally do not require a follow-up to the satellite. This greatly simplifies the design and construction of the antenna. For direct broadcasting satellites means that users who have antennas placed outside the house must not settle after being targeted once by satellite. Many satellites are placed on geostationary obit and a method to achieve this is based on the transfer of Hohmann.

This is the method used when it launches satellites into space using a ship bearing. Using this system, the satellite is placed on a low earth orbit (http://www.gpsphone-tracker.net/) at an altitude of around 290 km. After correct positioning this orbit missiles that are started to put the satellite into an elliptical orbit, with perigee and apogee low-Earth orbit to geosynchronous orbit. When the satellite reaches final altitude, rockets are again switched to stabilize the geostationary satellite orbit at the right speed. Sometimes when using rockets Ariane launch vehicle, the satellite is launched directly elliptical transfer orbit. When the satellite reaches maximum altitude missiles that are turned on to transfer to geostationary orbit desired, with appropriate speed.

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Laptop Buying Tips

Laptop Buying Tips


If you found this article means that you inform to purchase a quality laptop. Quality also means big budget, but also a bit of attention in terms of marketing they use stores. In addition, we must choose a brand ok, at a decent price with options that we really need. Lately the trend is for SSDs, so we find many offers laptops with SSD, SSH or both. If not even recommend buying one. I use both laptop and desktop, and the differences are enormous. Friends are always amazed at the reaction speed of the laptop. The trend is towards mobile world lately, using tablets, mobile “smart” even laptops with touchscreen. I myself have not yet caught touchscreen craze, I do not get along very well with the tablet, but the laptop is my friend. Owning a laptop almost 2 years and I can not number 5 says that would not have taken it after me.

As I said above, the stores will sell, so you will find all sorts of offers to purchase a laptop. Some good, some not so good. You must pay attention to detalii.Inainte buying a laptop is important to know what we will use the laptop. Tentinta the laptop is to be used for anything. If we use the laptop for video editing, photo editing, you need to take care and display that you choose. If you do edit a home, we can add a quality monitor, thus bump a little cheaper. For those using laptop for office, little things, I recommend a laptop easily, perhaps even an ultrabook, which means we can easily transport it. Also, a laptop battery should be looked good enough.

Many people do not put high price on brand. From my point of view it matters most. If you look at online stores, you will notice that there are many similar configurations, but with big differences of prices. Components are about the same, laptop manufacturers sourcing, most often from the same companies producing components. But the difference is by design, the way the components are assembled, the way they are cooled, place fans, display, etc. This makes a laptop to be more expensive or cheaper. Cooling is most important to a laptop. Placing fans, cooling components, all must be done with a purpose. Not all companies ‘thinking’ mind when conducting a laptop, so you have to search the internet opinions of those most achitionat kind of laptop. As well as manufacturing companies to provide information about cooling, but most often, they do not exist. Review sites only those who had the opportunity to open up. I put less value on cooling if you laptop models that do not have dedicated video card and SSD. They are ok from this point of view because not many sources that may overheated laptop.

I would choose a great laptop, 18 ‘, but none of the 12’. 15.6 ‘is a very good standard, neither too large nor too small. I would definitely not choose something smaller, it’s hard to handle on a small display, but no car to work every day to one of 18.4 ‘. In addition, the standard 15.6 “is manufactured in mass. The demand is great, just and demand, so prices are lower for 15.6. If we talk about resolution, we have a variety. The most common right now is HD Ready, ie 1366 x 768. 16 × 9 format is taken from cinema. Perhaps in time, with the entry 4K technology on the market, we have wide resolutions like 21: 9.

Gaming laptops not only have FULL HD resolution, ie 1920 × 1080 (16: 9) or 1920 × 1200 (16:10). From my point of view it is not worth to buy it. No there is no question yet of Ultra HD. The display is quite small laptop, we will probably stay with the browser zoom or lower resolutions. If you are interested in something, the best thing would be to go to a store that offers both options, it was a little button and see if it is ok.

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