Wi-fi Communication – Satellite
A satellite tv for pc is an object that revolves round one other object. For instance, earth is a satellite tv for pc of The Solar, and moon is a satellite tv for pc of earth.
A communication satellite tv for pc is a microwave repeater station in an area that’s used for telecommunication, radio and tv alerts. A communication satellite tv for pc processes the information coming from one earth station and it converts the information into one other kind and ship it to the second earth station.
Wi-fi Communication -How it Works
Two stations on earth need to talk by way of radio broadcast however are too distant to make use of standard means. The 2 stations can use a relay station for his or her communication. One earth station transmits the sign to the satellite tv for pc.
Uplink frequency is the frequency at which floor station is speaking with satellite tv for pc. The satellite tv for pc transponder converts the sign and sends it right down to the second earth station, and that is known as Downlink frequency. The second earth station additionally communicates with the primary one in the identical means.
Benefits of Satellit
Some great benefits of Satellite tv for pc Communications are as follows −
- The Protection space could be very excessive than that of terrestrial techniques.
- The transmission value is impartial of the protection space.
- Larger bandwidths are potential.
Disadvantages of Satellite tv for pc
The disadvantages of Satellite tv for pc Communications are as follows −
- Launching satellites into orbits is a expensive course of.
- The bandwidths are step by step used up.
- Excessive propagation delay for satellite tv for pc techniques than the standard terrestrial techniques.
Wi-fi Communication – Communication Fundamentals
The method of satellite tv for pc communication begins at an earth station. Right here an set up is designed to transmit and obtain alerts from a satellite tv for pc in orbit across the earth. Earth stations ship data to satellites within the type of excessive powered, excessive frequency (GHz vary) alerts.
The satellites obtain and retransmit the alerts again to earth the place they’re acquired by different earth stations within the protection space of the satellite tv for pc. Satellite tv for pc’s footprint is the realm which receives a sign of helpful energy from the satellite tv for pc.
The transmission system from the earth station to the satellite tv for pc by way of a channel is named the uplink. The system from the satellite tv for pc to the earth station by way of the channel is named the downlink.
Satellite tv for pc Frequency Bands
The satellite tv for pc frequency bands that are generally used for communication are the Cband, Ku-band, and Ka-band. C-band and Ku-band are the generally used frequency spectrums by in the present day’s satellites.
You will need to word that there’s an inverse relationship between frequency and wavelength i.e. when frequency will increase, wavelength decreases this helps to grasp the connection between antenna diameter and transmission frequency. Bigger antennas (satellite tv for pc dishes) are essential to assemble the sign with growing wavelength.
Wi-fi Communication -Earth Orbits
A satellite tv for pc when launched into area, must be positioned in sure orbit to supply a specific means for its revolution, in order to take care of accessibility and serve its objective whether or not scientific, army or business. Such orbits that are assigned to satellites, with respect to earth are known as as Earth Orbits. The satellites in these orbits are Earth Orbit Satellites.
The essential sorts of Earth Orbits are −
- Geo-synchronous Earth Orbit
- Geo-stationary Earth Orbit
- Medium Earth Orbit
- Low Earth Orbit
Geo-synchronous Earth Orbit (GEO)
A Geo-synchronous Earth orbit Satellite tv for pc is one which is positioned at an altitude of 22,300 miles above the Earth. This orbit is synchronized with a aspect actual day (i.e., 23hours 56minutes). This orbit can have inclination and eccentricity. It will not be round. This orbit could be tilted on the poles of the earth. But it surely seems stationary when noticed from the Earth.
The identical geo-synchronous orbit, whether it is round and within the aircraft of equator, it’s known as as geo-stationary orbit. These Satellites are positioned at 35,900kms (identical as geosynchronous) above the Earth’s Equator and so they carry on rotating with respect to earth’s route (west to east). These satellites are thought-about stationary with respect to earth and therefore the identify implies.
Geo-Stationary Earth Orbit Satellites are used for climate forecasting, satellite tv for pc TV, satellite tv for pc radio and different sorts of world communications.
The above determine reveals the distinction between Geo-synchronous and Geo- Stationary orbits. The Axis of rotation signifies the motion of Earth.
The primary level to notice right here is that each Geo-Stationary orbit is a Geo-Synchronous orbit. However each Geo-Synchronous orbit is NOT a Geo-stationary orbit.
Medium Earth Orbit (MEO)
Medium earth orbit (MEO) satellite tv for pc networks will orbit at distances of about 8000 miles from earth’s floor. Indicators transmitted from a MEO satellite tv for pc journey a shorter distance. This interprets to improved sign energy on the receiving finish. This reveals that smaller, extra light-weight receiving terminals can be utilized on the receiving finish.
Because the sign is travelling a shorter distance to and from the satellite tv for pc, there’s much less transmission delay. Transmission delay could be outlined because the time it takes for a sign to journey as much as a satellite tv for pc and again right down to a receiving station.
For real-time communications, the shorter the transmission delay, the higher would be the communication system. For instance, if a GEO satellite tv for pc requires 0.25 seconds for a spherical journey, then MEO satellite tv for pc requires lower than 0.1 seconds to finish the identical journey. MEOs operates within the frequency vary of two GHz and above.
Low Earth Orbit (LEO)
The LEO satellites are primarily labeled into three classes specifically, little LEOs, large LEOs, and Mega-LEOs. LEOs will orbit at a distance of 500 to 1000 miles above the earth’s floor.
This comparatively brief distance reduces transmission delay to solely 0.05 seconds. This additional reduces the necessity for delicate and hulking receiving tools. Little LEOs will function within the 800 MHz (0.eight GHz) vary. Large LEOs will function within the 2 GHz or above vary, and Mega-LEOs operates within the 20-30 GHz vary.
The upper frequencies related to Mega-LEOs interprets into extra data carrying capability and yields to the aptitude of real-time, low delay video transmission scheme.
Excessive Altitude Lengthy Endurance (HALE) Platforms
Experimental HALE platforms are principally extremely environment friendly and light-weight airplanes carrying communications tools. It will act as very low earth orbit geosynchronous .
These crafts shall be powered by a mix of battery and solar energy or excessive effectivity turbine engines. HALE platforms will supply transmission delays of lower than 0.001 seconds at an altitude of solely 70,000 toes, and even higher sign energy for very light-weight hand-held receiving gadgets.
Right here there could come up a query that with greater than 200 up there in geosynchronous orbit, how will we maintain them from working into one another or from making an attempt to make use of the identical location in area? To reply this drawback, worldwide regulatory our bodies just like the Worldwide Telecommunications Union (ITU) and nationwide authorities organizations just like the Federal Communications Fee (FCC) designate the areas on the geosynchronous orbit the place the communications satellites could be positioned.
These areas are laid out in levels of longitude and are known as as orbital slots. The FCC and ITU have progressively lowered the required spacing right down to solely 2 levels for C-band and Ku-band satellites because of the large demand for orbital slots.