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Egli Model
The Egli model is a terrain model for radio frequency propagation. This model, which was first introduced by John Egli in his 1957 paper, was derived from real-world data on UHF and VHF television transmissions in several large cities. It predicts the total path loss for a point-to-point link. Typically used for outdoor line-of-sight transmission, this model provides the path loss as a single quantity. Applicable to/under conditions The Egli model is typically suitable for cellular communication scenarios where one antenna is fixed and another is mobile. The model is applicable to scenarios where the transmission has to go over an irregular terrain. However, the model does not take into account travel through some vegetative obstruction, such as trees or shrubbery. Coverage Frequency: The model is typically applied to VHF and UHF spectrum transmissions. Mathematical formulation The Egli model is formally expressed as: P_ R= G_B G_M \left frac\right^2 \leftright2 P_T Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Propagation Model
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for amateur radio communications, international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems. Several different types of propagation are used in practical radio transmission systems. '' Line-of-sight propagation'' means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna. Line of sight transmission is used for medium-distance radio transmission, such as cell phones, cordless phones, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Path Loss
Path loss, or path attenuation, is the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system. This term is commonly used in wireless communications and signal propagation. Path loss may be due to many effects, such as free-space loss, refraction, diffraction, reflection, aperture- medium coupling loss, and absorption. Path loss is also influenced by terrain contours, environment (urban or rural, vegetation and foliage), propagation medium (dry or moist air), the distance between the transmitter and the receiver, and the height and location of antennas. Overview In wireless communications, path loss is the reduction in signal strength as the signal travels from a transmitter to a receiver, and is an application for verifying the loss. There are several factors that affect this: *Free-space path loss: This is the fundame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Point-to-point (telecommunications)
In telecommunications, a point-to-point connection refers to a communications connection between two communication endpoints or nodes. An example is a telephone call, in which one telephone is connected with one other, and what is said by one caller can only be heard by the other. This is contrasted with a ''point-to-multipoint'' or ''broadcast'' connection, in which many nodes can receive information transmitted by one node. Other examples of point-to-point communications links are leased lines and microwave radio relay. The term is also used in computer networking and computer architecture to refer to a wire or other connection that links only two computers or circuits, as opposed to other network topologies such as buses or crossbar switches which can connect many communications devices. ''Point-to-point'' is sometimes abbreviated as ''P2P''. This usage of ''P2P'' is distinct from ''P2P'' meaning ''peer-to-peer'' in the context of file sharing networks or other data- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line-of-sight Propagation
Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. Electromagnetic transmission includes light emissions traveling in a straight line. The rays or waves may be diffracted, refracted, reflected, or absorbed by the atmosphere and obstructions with material and generally cannot travel over the horizon or behind obstacles. In contrast to line-of-sight propagation, at low frequency (below approximately 3 MHz) due to diffraction, radio waves can travel as ground waves, which follow the contour of the Earth. This enables AM radio stations to transmit beyond the horizon. Additionally, frequencies in the shortwave bands between approximately 1 and 30 MHz, can be refracted back to Earth by the ionosphere, called skywave or "skip" propagation, thus giving radio transmissions in this range a potentially global reach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gain (electronics)
In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port by adding energy converted from some power supply to the signal. It is usually defined as the mean ratio of the signal amplitude or power at the output port to the amplitude or power at the input port. It is often expressed using the logarithmic decibel (dB) units ("dB gain"). A gain greater than one (greater than zero dB), that is, amplification, is the defining property of an active device or circuit, while a passive circuit will have a gain of less than one. The term ''gain'' alone is ambiguous, and can refer to the ratio of output to input voltage (''voltage gain''), current (''current gain'') or electric power (''power gain''). In the field of audio and general purpose amplifiers, especially operational amplifiers, the term usually refers to voltage gain, but in radio frequency amplifiers it usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Station
Base station (or base radio station, BS) is – according to the International Telecommunication Union's (ITU) Radio Regulations (RR) – a " land station in the land mobile service." A base station is called '' node B'' in 3G, '' eNB'' in LTE ( 4G), and '' gNB'' in 5G. The term is used in the context of mobile telephony, wireless computer networking and other wireless communications and in land surveying. In surveying, it is a GPS receiver at a known position, while in wireless communications it is a transceiver connecting a number of other devices to one another and/or to a wider area. In mobile telephony, it provides the connection between mobile phones and the wider telephone network. In a computer network, it is a transceiver acting as a switch for computers in the network, possibly connecting them to a/another local area network and/or the Internet. In traditional wireless communications, it can refer to the hub of a dispatch fleet such as a taxi or delivery fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna (radio)
In radio-frequency engineering, an antenna (American English) or aerial (British English) is an electronic device that converts an alternating current, alternating electric current into radio waves (transmitting), or radio waves into an electric current (receiving). It is the interface between radio waves Radio propagation, propagating through space and electric currents moving in metal Electrical conductor, conductors, used with a transmitter or receiver (radio), receiver. In transmission (telecommunications), transmission, a radio transmitter supplies an electric current to the antenna's Terminal (electronics), terminals, and the antenna radiates the energy from the current as electromagnetic radiation, electromagnetic waves (radio waves). In receiver (radio), reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplifier, amplified. Antennas are essential components ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Station
A mobile station (MS) comprises all user equipment and software needed for communication with a mobile network. The term refers to the global system connected to the mobile network, i.e. a mobile phone or mobile computer connected using a mobile broadband adapter. This is the terminology of 2G systems like GSM. In 3G systems, a mobile station (MS) is now referred to as user equipment (UE). In GSM, a mobile station consists of four main components: * Mobile termination (MT) - offers common functions such as: radio transmission and handover, speech encoding and decoding, error detection and correction, signalling and access to the SIM. The IMEI code is attached to the MT. It is equivalent to the network termination of an ISDN access. * Terminal equipment (TE) - is any device connected to the MS offering services to the user. It does not contain any functions specific to GSM. * Terminal adapter (TA) - provides access to the MT as if it were an ISDN network termination ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency
Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. The interval of time between events is called the period. It is the reciprocal of the frequency. For example, if a heart beats at a frequency of 120 times per minute (2 hertz), its period is one half of a second. Special definitions of frequency are used in certain contexts, such as the angular frequency in rotational or cyclical properties, when the rate of angular progress is measured. Spatial frequency is defined for properties that vary or cccur repeatedly in geometry or space. The unit of measurement of frequency in the International System of Units (SI) is the hertz, having the symbol Hz. Definitions and units For cyclical phenomena such as oscillations, waves, or for examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU Terrain Model
The ITU terrain loss model is a radio propagation model that provides a method to predict the median path loss for a telecommunication link. Developed on the basis of diffraction theory, this model predicts the path loss as a function of the height of path blockage and the First Fresnel zone for the transmission link. Applicable to / under conditions This model is applicable on any terrain. This model accounts for obstructions in the middle of the telecommunication link, and therefore, is suitable to be used inside cities as well as in open fields. Coverage Frequency: Any Distance: Any Mathematical formulation The model is mathematically formulated as: : A \; = \; 10 \; - \; 20 \; C_N : C_N \; = \; \frac : h \; = \; h_L \; - \; h_O : F_1 \; = \; 17.3 \; \sqrt Where, : A \; = Additional loss (in excess of free-space loss) due to diffraction (dB) : C_N \; = Normalized terrain clearance : h \; = The height difference (negative in the case that the LOS path is completely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Telecommunication Union
The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information and communications technology, information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union, the first formal and permanent international organization. The organization significantly predates the UN, making it the oldest UN agency. Doreen Bogdan-Martin is the Secretary-General of ITU, the first woman to serve as its head. The ITU was initially aimed at helping connect Telegraphy, telegraphic networks between countries, with its mandate consistently broadening with the advent of new communications technologies; it adopted its current name in 1932 to reflect its expanded responsibilities over radio and the telephone. On 15 November 1947, the ITU entered into an agreement with the newly cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
