SATELLITE TERMINOLOGY

Transcription

1 SATELLITE TERMINOLOGY Analogue Analogue is a method of signal transmission in which information is relayed by continuously altering the wave form of the electromagnetic current. AM / FM radio, VHS VCR tapes, vinyl records and traditional land line telephones are examples of Analogue communication. Audio/Video Jacks The A/V output jacks at the rear of a satellite receiver provide a superior picture and sound to your TV, VCR and Sound system. There are three jacks: one for the video, one for the right channel sound and one for the left channel sound. The audio jacks are necessary for the sound to be in stereo. Coaxial cable will not pass stereo sound to your television from the satellite receiver. Azimuth: Azimuth, is an angular measurement in a spherical coordinate system. The vector from an observer (origin) to a point of interest is projected perpendicularly onto a reference plane; the angle between the projected vector and a reference vector on the reference plane is called the azimuth. An example of an azimuth is the measurement of the position of a star in the sky. The star is the point of interest, the reference plane is the horizon or the surface of the sea, and the reference vector points to the north. The azimuth is the angle between the north point and the perpendicular projection of the star down onto the horizon. Azimuth is usually measured in degrees ( ). The concept is used in many practical applications including navigation, astronomy, engineering, mapping, mining and artillery. Bandwidth: Bandwidth is the complete range of frequencies over which a circuit or electronic system is allocated to function. Bandwidth is the range of frequencies, measured in hertz (Hz), that can pass over a given transmission channel. The bandwidth determines the rate at which information can be transmitted through the circuit. Beam width: Beam width, as used in RF transmission of an antenna pattern, is the angle between the half-power (3-dB) points of the main lobe when referenced to the peak effective radiated power of the main lobe. Note: Beam width is expressed in degrees related along the horizontal plane. Bent-pipe: Bent-pipe is a signal relay scheme in which a terrestrial-based signal is sent to a satellite, which then relays the signal back to earth with minimal processing by the satellite. Bit: Binary digit: The smallest unit of data in a digital system, with a value of either 0 or 1. A group of bits, such as 8- bits or 16-bits, compose a byte. The number of bits in a byte depends upon the processing system being used. Whenever you see a lowercase b associated with a number, it's likely to be a bit. It can be prefixed with kilo- (for 1,024 bits, or 2 to the 10th power) or mega- (1,024 x 1,024 bits)--and sometimes finds its way into data transfer speeds (such as 14.4 kbps).

2 Broadband: Broadband is the transmission of multiple channels of data over a single communications medium. It also commonly refers to a transmission greater than 128 Kbps. Broadband Satellite: A Broadband Satellite is a special high-bandwidth satellite that provides multiple channels of data over a single communications beam. Byte: Byte is a group of data bits that are processed together. Typically, a byte consists of 8 bits. There are kilobytes, Megabytes, Gigabytes, Terabytes, etc. 1 Byte = 8 bits, 1 kilobyte = about 1,000 bytes 1 Megabyte = about 1,000,000 bytes 1 Gigabyte = 1,000,000,000 bytes 1 Terabyte = 1,000,000,000,000 bytes. Carrier Carrier is a telephone long distance company that operates fiber/satellite/microwave networks to carry voice and data traffic. A local exchange carrier (LEC) is a local phone company and an inter-exchange carrier (IEC or IXC) carries long-distance calls. 2) A continuous radio frequency (RF) signal used to carry another information signal Cache Cache is a place to store something temporarily. Web pages you request are stored in your browser's cache directory on your hard disk. When you return to a page you've recently viewed, the browser gets it from the cache rather than the original server, saving you time and the network additional traffic. You can usually vary the size of your cache, depending on your particular browser C Band C band is a name given to certain portions of the electromagnetic spectrum, including wavelengths of microwaves that are used for long-distance radio telecommunications. The IEEE C-band - and its slight variations - contains frequency ranges that are used for many satellite communications transmissions, some Wi- Fi devices, some cordless telephones, and some weather radar systems. For satellite communications, the microwave frequencies of the C-band perform better under adverse weather conditions in comparison with Kuband (11.2 GHz to 14.5 GHz) microwave frequencies, which are used by another large set of communication satellites. Portions of this band are dedicated to satellite communications. Satellite downlinks are 3.7 to 4.2 GHz Channel Channel is path for electrical communication between two facilities. It is also called a circuit, link or path. Circuit: A satellite link

3 Circular Polarization: Circular Polarization is the peculiar condition of a RF transmission, in consequence of which they exhibit different properties in different directions. A signal transmitted from a transceiver at an angle (called the angle of polarization) will only be received by a similar transceiver when the transceiver are parallel to each and no when they are perpendicular to each other. If a transmission beam, which has been transmitted from a transceiver at an angle of about 56 deg, be received upon a second transceiver similar to the former, and at the same angle of inclination, the beam will be readily received when the two planes of incidence are parallel to each other, but will not be received when the two planes of inclination are perpendicular to each other. The beam has, therefore, acquired new properties by transmission from the first transceiver, and is called polarized transmission, while the modification which the beam has experienced by this transmission is called polarization. The inclination in which the beam is transmitted from the first transceiver is called the angle of polarization. A signal beam reflected from a metallic surface acquires properties still more complex, its vibrations being no longer rectilinear, but circular, or elliptical. This phenomenon is called circular or elliptical polarization. Clarke Belt: Named after its founder Arthur C. Clarke, the Clarke Belt is an orbit used by satellites at a height of 22,250 miles, in which satellites make an orbit in 24 hours, yet remain in a fixed position relative to the earth s surface. Closed Captioning: Text stream included in broadcast signal that provides narrative description of dialogue, action, sounds, and other elements of the picture. Most often used by the hearing impaired and in environments where audio is undesirable (such as in restaurants). Coax Cable: Coax or coaxial cable is the standard type of cable used by all satellite TV technicians. The cable is round and is available in black, gray and white although black is most common used. Coax cable carries the signal from the dish to the satellite receiver and on to your Router. The types used on YahClick are RG6 and RG11. Component video: Component video uses three cables to carry video signals. These three cables contain signals that represent the levels of Red, Blue and Green in the video signals. They do not directly transfer the actual levels of Red, Blue and Green (RGB), but an accurate representation of those levels in the original video signal. These cables and their corresponding connections on the back of HDTV sets, DVDS, and HD satellite receivers are called: Y, B-Y, and R-Y. Y: Contains the "Luminance Signal". The luminance signal represents the levels of black and white with in the video signal. B-Y: Contains the difference of how much blue there is in the video signal relative to the luminance signal. R-Y: Contains the difference of how much red there is in the video signal relative to the luminance signal. Compression: Compression is a term used to denote reducing the amount of bandwidth needed to transmit video or audio, thus increasing the capacity of a satellite transponder. Signal Compression can lead to a lower image quality, depending on the degree and method used to compress the signal. When used on Internet video, compression allows a video to be transferred faster than an uncompressed video. The loss of image quality is offset by the shorted down load time.

4 Decibel A decibel is a unit of measurement. Decibels use a logarithm to allow very large or very small differences between to two values to be represented in small numbers. In Electronics, a decibel can be represented as dbm for measurements of micro watts. Zero dbm is the representation for 1 milli watt of signal power. For every 3 dbm increase in signal power the actual milli watt increase is about double. All splitters, amplifiers, coax cable used with satellite and television signals have specifications which state signal losses, or increases using the db unit of measurement. A signal level measuring 6 db is twice as strong as one measuring 3dB and half as strong as 9dB. Digital Compression: A process of translating video images into a digital code which takes up less transmission space than the original signal would have. This allows more channels per satellite transponder: from four-to-one for live video to eight-toone for film. DiSEqC: DiSEqC (Digital Satellite Equipment Control) system, which is a communication bus between satellite receivers and peripheral equipment using only the existing coaxial cable. DiSEqC can be integrated into consumer satellite installations to replace all conventional analogue switching, providing a standardized digital system with non-proprietary commands and enabling switching in multi-satellite installations. Dolby Digital / AC-3 Compatible: Dolby Digital provides 6 independent sound track channels through the optical output jack. When connected to your AC3 compatible home theatre audio setup, this connection provides Dolby Digital Surround Sound (when Dolby Digital is part of the programming being viewed). DVB: Digital Video Broadcast standard for digital radio and television, using MPEG2 compression. DVB is being supported by all European manufacturers and broadcasters. Earth Station A ground-based antenna and associated equipment used to receive and/or transmit telecommunications signals via satellite. It is a terrestrial terminal station. Ground stations are located either on the surface of the Earth, or within the atmosphere. Earth stations communicate with spacecraft by transmitting and receiving radio waves in the super high frequency or extremely high frequency bands (e.g., microwaves). When a ground station successfully transmits radio waves to a spacecraft (or vice versa), it establishes a telecommunications link. Specialized satellite earth stations are used to telecommunicate with satellites, mainly communications satellites. (The YahClick services in South Africa make use of a earth station in Luxemburgh) When a satellite is within a ground station's line of sight, the station is said to have a view of the satellite. It is possible for a satellite to communicate with more than one ground station at a time. A pair of ground stations are said to have a satellite in mutual view when the stations share simultaneous, unobstructed, line-of-sight contact with the satellite EIRP In radio communication systems, Equivalent isotropically radiated power (EIRP) or, alternatively, Effective isotropically radiated power is the amount of power that a theoretical isotropic antenna (which evenly distributes power in all directions) would emit to produce the peak power density observed in the direction of maximum

5 antenna gain. EIRP can take into account the losses in transmission line and connectors and includes the gain of the antenna. The EIRP is often stated in terms of decibels over a reference power emitted by an isotropic radiator with an equivalent signal strength. The EIRP allows comparisons between different emitters regardless of type, size or form. From the EIRP, and with knowledge of a real antenna's gain, it is possible to calculate real power and field strength values. Elevation: The upward tilt to a satellite dish antenna measured in degrees required to aim the antenna at the communications satellite. When aimed at the horizon, the elevation angle is zero. If it were tilted to a point directly overhead, the satellite antenna would have an elevation of 90 degrees. Feed Horn: A device which collects the signals at the focus of the satellite dish and channels them to the LNB. Footprint/ Coverage Area An area of the earth that the signal transmitted from a communications satellite is able to reach with a usable signal. The footprint depends on the satellites beam. Frequency: The rate at which a signal (e.g. electrical current) alternates. The standard unit of frequency is the hertz, abbreviated Hz. If a signal completes one cycle per second, then the frequency is 1 Hz; 60 cycles per second equals 60 Hz. Hz: Hertz. The name of the basic measure of frequency at which an electromagnetic wave completes a full cycle from its positive to its negative pole and back again. Each unit is equal to one cycle per second. KHz: Kilohertz. Refers to a unit of frequency equal to 1,000 Hertz. MHz: Megahertz. Refers to a frequency equal to one million Hertz. GHz: Gigahertz. Refers to a frequency equal to one billion Hertz Frequency Bands Spectrum Downlink Uplink Bandwidth L 1.5GHz 1.6GHz 15MHz S 1.9GHz 2.2GHz 70MHz C 4GHz 6GHz 500MHz Ku 11GHz 14GHz 500MHz Ka 20GHz 30GHz 3500MHz Gain: Gain is an increase in signal power by amplification, expressed as the ratio of output to input. Antenna gain is a measure of the ability of the antenna to focus signal waves in a particular direction. A single dipole antenna (rabbit ears are single dipole TV antenna) is said to have 0 gains.

6 Gauge: Gauge is a unit used to measure wire thickness. The smaller the number, the thicker the wire. (i.e. 10 gauge wire is much thicker than 16 gauge wire). Geostationary: Satellites orbit the Earth 35,786 km above the Equator and rotate at the same relative speed and direction as the Earth's surface. Therefore, the satellites appear stationary. GPS Global Positioning System. A satellite system that provides precise reference to the location of a point on earth. GPS satellite systems employ lower orbiting satellites than geostationary satellite networks. HDTV: High Definition Television is a digital television format, which combines high-resolution video and theatre like sound to create a movie theatre quality TV viewing experience. IP: Internet protocol (IP) is the method by which data is sent from one computer to another on the Internet. Each computer on the Internet has at least one IP address that uniquely identifies it from all other computers on the Internet. When you send or receive data (for example, an note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender's Internet address and the receiver's address Installation: Setting up the customer's premises equipment. Installation includes mounting the satellite dish antenna, positioning it to receive a signal, and activating service to surf the web. Installer : A Installer is a trained field service technician that provides installation services. Installers are certified to install YahClick services Internet Service Provider (ISP): An organization providing Internet access to the public using computer servers connected directly to the Internet. Kbps: Kilobits per second. It refers to transmission speed of 1,000 bits per second. Ka-Band: The Ka band covers the frequencies of GHz. The Ka band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above" in other words, the band directly above the K-band. The 30/20 GHz band is used in communications satellites, uplink in either the 27.5 GHz and 31 GHz bands and high-resolution, close-range targeting radars aboard military airplanes. The designation "Ka-band" is from Kurz-above, which stems from the German word "kurz" meaning short.

7 In satellite communications, the Ka band allows higher bandwidth communication, and is going to be used in the upcoming Iridium Next satellite series, for instance. Unlike the Ku and the C bands, however, it is far more susceptible to signal attenuation under rainy conditions Band of frequencies from 19 to 30 Hz (billion cycles per second) that are use for HDTV, MPEG4, Broadband Internet and general data. Ka band provides faster data transfer rates which is needed for MPEG4 and other fast data protocols for voice, video and data. KaKu: Refers to a Satellite Dish used to receiver both Ka and Ku satellite signals. Go here for more information Ku-band: Band of frequencies from 11 to 14 GHz (billion cycles per second) that are used increasingly by communications satellites. Requires large ground antennas, usually 6 to 12 feet in diameter The Ku band is a portion of the electromagnetic spectrum in the microwave range of frequencies. This symbol refers to (originally German: Kurz-unten) in other words, the band directly below the K-band. In radar applications, it ranges from GHz Ku band is primarily used for satellite communications, most notably for fixed and broadcast services, and for specific applications such as NASA's Tracking Data Relay Satellite used for both space shuttle and ISS communications. Ku band satellites are also used for backhauls and particularly for satellite from remote locations back to a television network's studio for editing and broadcasting. The band is split into multiple segments that vary by geographical region by the International Telecommunication Union (ITU). NBC was the first television network to uplink a majority of its affiliate feeds via Ku band in LAN Local Area Network. A local area network (LAN) is a group of computers and associated devices that share a common communications line and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared in common by multiple computer users. L-Band: L band is a frequency range between 390MHz and 1.55GHz which is used for satellite communications and for terrestrial communications between satellite equipment. Longitude: Longitude is the angular distance on the earth's surface, measured east or west from the prime meridian at Greenwich, England, to the meridian passing through a position, expressed in degrees (or hours), minutes, and seconds. Satellites in geostationary orbit are position in orbital slots based on the longitude of the orbital position. Seattle WA is at 122 degrees west longitude. A satellite positioned at 121 longitudes would be located 1 degree east of due south. A location at 110 degrees longitude would point a dish approximately 11 degrees east of their due south to receive the same satellite. LNB: The Low Noise Block (LNB) is the device located on the front arm of the Satellite Dish. The LNB receives the bounced satellite signals from the dish reflector, amplifies the weak signal and lowers the signal frequency to a frequency capable of traveling down a coax cable. There are several types of LNB, with most only working on a specific dish type. A dual LNB can accommodate up to two satellite receivers or one Trio / Ultimate TV receiver.

8 By using a Matrix switch you can add more than two receivers to a dual LNB. If you are using a Multi-Satellite dish you will need to use a Multi-satellite switch capable of handling the number of receivers you wish to use. MPEG2: MPEG2 is a video compression method. Compression is used to combine several programs into one satellite transponder. MPEG2 is also used to compress video for internet use. MPEG2 will be used for many years more as MPEG4 is slowly introduced into the market, Multi-satellite dish: Satellite program providers maintain broadcast satellites in multiple orbit locations to provide wider signal coverage and greater programming variety. In order to receive programming that extends beyond the satellite provider's "core" programming examples include HDTV programs, and local channels in many areas NTSC: National Television Standards Committee A video standard established by the United States (RCA/NBC} and adopted by numerous other countries, like SA. Orbital Slots: A geostationary orbit, or Geostationary Earth Orbit (GEO), is a circular orbit 35,786 km (22,236 mi) above the Earth's equator and following the direction of the Earth's rotation. An object in such an orbit has an orbital period equal to the Earth's rotational period (one sidereal day), and thus appears motionless, at a fixed position in the sky, to ground observers. Communications satellites and weather satellites are often given geostationary orbits, so that the satellite antennas that communicate with them do not have to move to track them, but can be pointed permanently at the position in the sky where they stay. A geostationary orbit is a particular type of geosynchronous orbit Pixelization: Occurs due to errors in decoding the MPEG bit stream Areas or patches of blocks of color appear instead of the higher resolution image. It appears as though parts of the image have been "censored" or "disguised" in such a way to make the underlying video unidentifiable. It might be described as the picture "breaking up". The condition is usually more discernible in fast action or motion images. The patches of blocks appear and disappear, and can happen anywhere on the screen but usually are "part" of the image "in motion". Pixelization most often occurs during rain fade or if the satellite system has to low of a signal strength to operate properly PVR: Personnel Video Recorder. A PVR satellite receiver has a built in hard drive for digitally recording satellite television programs. Dual tuners allow the user to record one program while watching another or record two programs at the same time. Rain fades: Rain fade refers primarily to the absorption of a microwave radio frequency (RF) signal by atmospheric rain, snow or ice, and losses are especially prevalent at frequencies above 11 GHz. It also refers to the degradation of a signal caused by the electromagnetic interference of the leading edge of a storm front. Rain fade can be caused by precipitation at the uplink or downlink location. However, it does not need to be raining at a location for it to be affected by rain fade, as the signal may pass through precipitation many miles away, especially if the satellite dish has a low look angle. From 5 to 20 percent of rain fade or satellite signal attenuation may also be caused by rain, snow or ice on the uplink or downlink antenna reflector, radome or feed horn. Possible ways to overcome the effects of rain fade are site diversity, uplink power control, variable rate encoding, receiving

9 antennas larger than the requested size for normal weather conditions, and hydrophobic coatings. Only superhydrophobic, Lotus effect surfaces repel snow and ice. Receiver: The IRD Unit which takes signals from a satellite dish and converts them so that they can appear on TV. Remote Extender: After market devices that allows you to use an Infrared (IR) remote to control a satellite receiver from another room. RG-59: A common coax cable used in many homes for the last 40 years. RG-6: The type of coax cable recommended for digital satellite TV installations. RG-6 is a larger-size cable than the lower-grade RG-59 cable found in some homes. RG-59 has a small center conductor, a small insulating dielectric (white foam inside the cable) and typically a single outer shield. By comparison, RG-6 has a larger centre conductor, a dual or quad shield, and a much larger insulating dielectric, ensuring greater bandwidth and lower frequency loss per foot. R/F connectors: Output/Input screw on connections for coaxial cable. R/F connectors will not provide stereo from the satellite receiver to the TV or stereo Router An intelligent device that supports connectivity by "routing" packets of information to their destination. Routers ensure that packets always arrive at their proper destination. Satellite: A sophisticated electronic communications relay station orbiting 22,237 miles above the equator moving in a fixed orbit at the same speed and direction of the earth (about 7,000 mph east to west). Satellite Dish: A satellite dish is used to collect signals from a satellite in orbit and focus them to the front of the dish where a feed horn collects them and passes the signals on to the LNB to be amplified and sent to a satellite receiver. The larger the dish the more signal collected. The total amount of signal collected is a combination of the strength of the broadcasting satellite, the foot print of the satellite and the amount of signal the dish can actual collect and focus. In a digital system, the larger the dish does not translate into a better picture. A larger dish will reduce the effects of rain fade but not provide a better picture in normal operating conditions. Solar Outage: Solar outage, sun transit or sun fade is an interruption in or distortion of geostationary satellite signals caused by interference from solar radiation. The effect is due to the sun's radiation overwhelming the satellite signal. In the northern hemisphere, sun outages occur before the March equinox (February, March) and after the September equinox (September and October), and in the southern hemisphere the outages occur after the March equinox

10 and before the September equinox. At these times, the apparent path of the sun across the sky takes it directly behind the line of sight between an earth station and a satellite. The sun radiates strongly across the entire spectrum, including the microwave frequencies used to communicate with satellites (C-band, Ku band, and Ka band) the sun swamps the signal from the satellite. The effects of a sun outage range from partial degradation (increase in the error rate) to total destruction of the signal. The effect sweeps from north to south from appoximately 20 February to 20 April, and from south to north from approximately 20 August to 20 October, affecting any specific location for less than 12 minutes a day for a few consectutive days Spectrum The range of electromagnetic radio frequencies used in transmission of voice, data and television Splitter: A passive device (one with no active electronic components) which distributes a television signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously. Spot Beam A spot beam, in telecommunications parlance, is a satellite signal that is specially concentrated in power (i.e. sent by a high-gain antenna so that it will cover only a limited geographic area on Earth. Spot beams are used so that only earth stations in a particular intended reception area can properly receive the satellite signal. Spot beams allow satellites to transmit different data signals using the same frequency. Because satellites have a limited number of frequencies to use, the ability to re-use a frequency for different geographical locations (without different data interfering with each other at the receiver) allows for more local channels to be carried, since the same frequency can be used in several regions. System Test: This function provides a standard test sequence to help evaluate any problems with a Satellite TV system. Transponder: A satellite component that receives, modulates, amplifies, and retransmits a signal. Through MPEG compression more than one television or audio channel are transmitted over a signal transponder. When you look at the signal strength screen from a satellite receiver, you are given the ability to check the signal strength on different transponders. Each transponder is responsible for a several or even a dozen or more satellite channels. Since each transponder is a separate electronic component on the satellite, you will see a difference in signal strength from one transponder to another. Some transponders will show no signal strength. This is a result of spot beams and is normal operation. Widescreen: Term given to picture displays with a wider aspect ratio than NTSC 4:3. Digital HDTV is 16:9 widescreen. Most motion pictures also have a widescreen aspect ratio, some even wider than 16:9.