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Microwave link design ppt

Microwave link design ppt
A microwave link is a communications system that uses a beam of radio waves in the microwave frequency range to transmit information between two fixed locations on the earth. They are crucial to many forms of communication and impact a broad range of industries. Broadcasters use microwave links to send programs from the studio to the transmitter location, which might be miles away. Microwave links carry cellular telephone calls between cell sites. Wireless Internet service providers use microwave links to provide their clients with high-speed Internet access without the need for cable connections. Telephone companies transmit calls between switching centers over microwave links, although fairly recently they have been largely supplanted by fiber-optic cables. Companies and government agencies use them to provide communications networks between nearby facilities within an organization, such as a company with several buildings within a city. One of the reasons microwave links are so adaptable is that they are broadband. That means they can move large amounts of information at high speeds. Another important quality of microwave links is that they require no equipment or facilities between the two terminal points, so installing a microwave link is often faster and less costly than a cable connection. Finally, they can be used almost anywhere, as long as the distance to be spanned is within the operating range of the equipment and there is clear path that is, no solid obstacles between the locations. A simple one-way microwave link includes four major elements: a transmitter, a receiver, transmission lines, and antennas. These basic components exist in every radio communications system, including cellular telephones, two-way radios, wireless networks, and commercial broadcasting. But the technology used in microwave links differs markedly from that used at the lower frequencies longer wavelengths in the radio spectrum. Techniques and components that work well at low frequencies are not useable at the higher frequencies shorter wavelengths used in microwave links. For example, ordinary wires and cables function poorly as conductors of microwave signals. On the other hand, microwave frequencies allow engineers to take advantage of certain principles that are impractical to apply at lower frequencies. Such antennas can be designed to operate at much lower frequencies, but they would be too large to be economical for most purposes. In a microwave link the transmitter produces a microwave signal that carries the information to be communicated. That information—the input—can be anything capable of being sent by electronic means, such as a telephone call, television or radio programs, text, moving or still images, web pages, or a combination of those media. The transmitter has two fundamental jobs: generating microwave energy at the required frequency and power level, and modulating it with the input signal so that it conveys meaningful information. Flashing a light to transmit a message in Morse Code is an example of modulation. The differing lengths of the flashes the dots and dashesand the intervals of darkness between them, convey the information—in this case a text message. The second integral part of a microwave link is a transmission line. This line carries the signal from the transmitter to the antenna and, at the receiving end of the link, from the antenna to the receiver. In electrical engineering, a transmission line is anything that conducts current from one point to another. Lamp cord, power lines, telephone wires and speaker cable are common transmission lines. But at microwave frequencies, those media excessively weaken the signal. In their place, engineers use coaxial cables and, especially, hollow pipes called waveguides. The third part of the microwave system is the antennas. On the transmitting end, the antenna emits the microwave signal from the transmission line into free space. At the receiver site, an antenna pointed toward the transmitting station collects the signal energy and feeds it into the transmission line for processing by the receiver. Antennas used in microwave links are highly directional, which means they tightly focus the transmitted energy, and receive energy mainly from one specific direction. This contrasts with antennas used in many other communications systems, such as broadcasting. Since microwaves travel in essentially straight lines, man-made obstacles including possible future construction that might block the signal must either be overcome by tall antenna structures or avoided altogether. Natural obstacles also exist. Flat terrain can create undesirable reflections, precipitation can absorb or scatter some of the microwave energy, and the emergence of foliage in the spring can weaken a marginally strong signal, which had been adequate when the trees were bare in the winter. Engineers must take all the existing and potential problems into account when designing a microwave link. At the end of the link is the final component, the receiver. Microwave link design ppt
Copy embed code:. Automatically changes to Flash or non-Flash embed. WordPress Embed Customize Embed. URL: Copy. Presentation Description No description available. One method of calculation is based on knife edge approximation. The free space loss of the radio signal is subtracted. In new generation microwave radios with power forward error correction schemes this difference is 0. Four fading types are considered while planning links. A reflected wave causes a multipath, i. The duplex spacing is always sufficiently large so that the radio equipment can operate interference free under duplex operation. One such vendor independent tool is Pathloss 4. This tool is probably one of the best tools for complex microwave design. It includes North American and ITU standards, different diversity schemes, diffraction and reflection multipath analysis, rain effects, interference analysis etc. An outage in a digital microwave link occurs with a loss of Digital Signal frame sync for more than 10 sec. Digital signal frame loss typically occurs when the BER increases beyond 1 x The objectives of digital links are divided into separate grades: high, medium and local grade. The medium grade has four quality classifications. Use updated maps that are not more than a year old. The terrain itself can change drastically in a very short time period. Make sure everyone on the project is using the same maps, datums and coordinate systems. Microwave hops over or in the vicinity of the large water surfaces and flat land areas can cause severe multipath fading. Reflections may be avoided by selecting sites that are shielded from the reflected rays. Follow us on:. Go to Application. US Go Premium. PowerPoint Templates. Upload from Desktop Single File Upload. Post to :. URL :. Related Presentations :. Add to Channel. The presentation is successfully added In Your Favorites. Views: Category: Entertainment. Like it 0. Dislike it 0. Added: September 18, Posting comment To browse Academia. Skip to main content. Log In Sign Up. Prasant Swain. One method of calculation is based on knife edge approximation. The absorption peaks are located around 23GHz for water molecules and 50 to 70 GHz for oxygen molecules. In-3 new generation microwave radios with power forward error correction schemes this difference is 0. Four fading types are considered while planning links. A reflected wave causes a multipath, i. The total annual rainfall in an area has little relation to the rain attenuation for the area — Hence a margin is included to compensate for the effects of rain at a given level of availability. Increased fade margin margins as high as 45 to 60dB is of some help in rainfall attenuation fading. The duplex spacing is always sufficiently large so that the radio equipment can operate interference free under duplex operation. One such vendor independent tool is Pathloss 4. This tool is probably one of the best tools for complex microwave design. It includes North American and ITU standards, different diversity schemes, diffraction and reflection multipath analysis, rain effects, interference analysis etc. Interference in microwave systems is caused by the presence of an undesired signal in a receiver. When this undesired signal exceeds certain limiting values, the quality of the desired received signal is affected. To maintain reliable service, the ratio of the desired received signal to the undesired interfering signal should always be larger than the threshold value. The actual IFM value used in a path calculation depends on the method of frequency coordination being used. An outage in a digital microwave link occurs with a loss of Digital Signal frame sync for more than 10 sec. Digital signal frame loss typically occurs when the BER increases beyond 1 x The objectives of digital links are divided into separate grades: high, medium and local grade. The medium grade has four quality classifications. The terrain itself can change drastically in a very short time period. Make sure everyone on the project is using the same maps, datums and coordinate systems. Maps are used only for initial planning, as a first approximation. It also increases with frequencyclimatic factors and average annual temperature. Microwave link installation is performed by DragonWave-X qualified and certified crews. Crews can be scaled to meet the build-out market demand and project schedule. All resources within a crew adhere to all local safety laws and carry safety certifications. Watch Harmony Radio Lite Installation. After microwave link installation, DragonWave-X certified resources perform microwave link alignment and testing. Microwave link decommissioning is performed by DragonWave-X qualified and certified crews. Crews with remove existing legacy equipment and dispose in accordance by customer or in an environmentally conscience manner. DragonWave-X is a leading provider of high-capacity packet microwave solutions that drive next-generation IP networks. Skip to main content. Microwave Link Installation, Alignment and Testing. RF design parameters Photos of complete installation — cabinet, lines, tower etc. Contact Us Contact us online or view our directory. Latest Tweets. Loading tweets Contact Us. About DragonWave -X. Leave this field blank. Blog Icon. All relevant state-of-the-art concepts have been carefully implemented without compromise. RAy is well proven within the market since in thousands of installations in tens of countries from the poles to the equator. It is used by Internet Service Providers as well as global Telco operators for both, backbone and last-mile microwave links. Take the opportunity to remotely access and test a live RAy link. The first unit you may access herethe second here admin, RacomDemo Product overview. Just leave your laptop and voltmeter at home when you go to adjust your antennas and setup the units! This name is used for all products within the same product family. Possible values: 10, 11, 17, 18, Generally more variants can be used within one unit, i. SW encryption may be possible. Possible values: L — unit transmits on lower part of the band U — unit transmits on upper part of the band. SW key activates the Data speedswhich are under the specific license. SW keys and Optional accessories are not HW dependent and can be ordered later on, so they are not printed on Product label. Technical parameters are subject to change without prior notification. Specifications RAy3. RACOM is a primary producer and therefore does not provide delivery of all available accessories for its products. Components are only held in limited quantities and the delivery date may therefore be affected by the need for subcontracting. If you require other accessories, please contact us or your supplier. Fibre optic cables The correct type of fiber optic cable and connector depends on the SFP module you are using. All common types are supported. All common types of SFP modules are supported. If you require anything else, please contact us or your supplier. Frequency [GHz] Frequency used for calculation. Options supported by the link. Sensitivity [dBm] The guaranteed sensitivity for a BER of 10 -6 for the chosen channel spacing and modulation. Antenna gain [dBi] Antenna gain at the centre of the frequency band. Antenna height [m] Antenna height above ground. Site name For improved orientation. Without these only RSS and fade margin is calculable. You can use map to select points. Distance [km] The distance between the end points of the link. The end points must be in line of sight with a sufficient margin for the Fresnel zone. The calculation for RAy 10 is possible for the distances from 0. The calculation for RAy 11 is possible for the distances from 0. After you enable Flash, refresh this page and the presentation should play. Get the plugin now. Toggle navigation. Help Preferences Sign up Log in. To view this presentation, you'll need to allow Flash. Click to allow Flash After you enable Flash, refresh this page and the presentation should play. View by Category Toggle navigation. Products Sold on our sister site CrystalGraphics. Tags: design link microwave. Latest Highest Rated. Frequencies gt 15 GHz are essentially used for short-haul transmission. Fresnel zones are specified employing ordinal numbers that correspond to the number of half wavelength multiples that represent the difference in radio wave propagation path from the direct path The Fresnel Zone must be clear of all obstructions. One method of calculation is based on knife edge approximation. The absorption peaks are located around 23GHz for water molecules and 50 to 70 GHz for oxygen molecules. When reflection cannot be avoided, the fade margin may be adjusted by including this contribution as additional loss in the link budget 24 Signal strength versus reflection coefficient 10 Amax 0 Amin Signal Strength dB 0. The free space loss of the radio signal is subtracted. The radio can handle anything that affects the radio signal within the fade margin but if it is exceeded, then the link could go down and therefore become unavailable 30 Link Budget The threshold level for BER for microwave equipment used to be about 3dB higher than for BER In new generation microwave radios with power forward error correction schemes this difference is 0. Four fading types are considered while planning links. They are all dependent on path length and are estimated as the probability of exceeding a given calculated fade margin 33 Fading and Fade margins Multipath fading - Flat fading - Frequency-selective fading Rain fading Refraction-diffraction fading k-type fading 34 Fading and Fade margins Multipath Fading is the dominant fading mechanism for frequencies lower than 10GHz. A reflected wave causes a multipath, i. This is called upfade 35 Fading and Fade margins Upfademax10 log d 0. A location where a signal is canceled out by multipath is called null or downfade As a thumb rule, multipath fading, for radio links having bandwidths less than 40MHz and path lengths less than 30Km is described as flat instead of frequency selective 36 Fading and Fade margins Flat fading A fade where all frequencies in the channel are equally affected. There is barely noticeable variation of the amplitude of the signal across the channel bandwidth If necessary flat fade margin of a link can be improved by using larger antennas, a higher-power microwave transmitter, lower loss feed line and splitting a longer path into two shorter hops On water paths at frequencies above 3 GHz, it is advantageous to choose vertical polarization 37 Fading and Fade margins Frequency-selective fading There are amplitude and group delay distortions across the channel bandwidth It affects medium and high capacity radio links gt32 Mbps The sensitivity of digital radio equipment to frequency-selective fading can be described by the signature curve of the equipment This curve can be used to calculate the Dispersive Fade Margin DFM 38 Fading and Fade margins DFM Only a major error in path engineering wrong antenna or misalignment over the high-clearance path could cause dispersive fading problems 39 Fading and Fade margins Rain Fading Rain attenuates the signal caused by the scattering and absorption of electromagnetic waves by rain drops It is significant for long paths gt10Km It starts increasing at about 10GHz and for frequencies above 15 GHz, rain fading is the dominant fading mechanism Rain outage increases dramatically with frequency and then with path length 40 Fading and Fade margins Microwave path lengths must be reduced in areas where rain outages are severe The available rainfall data is usually in the form of a statistical description of the amount of rain that falls at a given measurement point over a period of time. The total annual rainfall in an area has little relation to the rain attenuation for the area Hence a margin is included to compensate for the effects of rain at a given level of availability. Increased fade margin margins as high as 45 to 60dB is of some help in rainfall attenuation fading. For high k values, the Earths surface gets close to a plane surface and better LOS lower antenna height is obtained The probability of refraction-diffraction fading is therefore indirectly connected to obstruction attenuation for a given value of Earth radius factor Since the Earth-radius factor is not constant, the probability of refraction-diffraction fading is calculated based on cumulative distributions of the Earth-radius factor 44 Frequency planning The objective of frequency planning is to assign frequencies to a network using as few frequencies as possible and in a manner such that the quality and availability of the radio link path is minimally affected by interference. The following aspects are the basic considerations involved in the assignment of radio frequencies 45 Frequency planning Determining a frequency band that is suitable for the specific link path length, site location, terrain topography and atmospheric effects Prevention of mutual interference such as interference among radio frequency channels in the actual path, interference to and from other radio paths, interference to and from satellite communication systems Correct selection of a frequency band allows the required transmission capacity while efficiently utilizing the available radio frequency spectrum 46 Frequency planning Assignment of a radio frequency or radio frequency channel is the authorization given by an administration for a radio station to use a radio frequency or radio frequency channel under specified conditions. In India the authority is WPC Wireless Planning Coordination Wing 47 Frequency planning Frequency channel arrangements The available frequency band is subdivided into two halves, a lower go and an upper return duplex half. The duplex spacing is always sufficiently large so that the radio equipment can operate interference free under duplex operation. The width of each channel depends on the capacity of the radio link and the type of modulation used 48 Frequency planning The most important goal of frequency planning is to allocate available channels to the different links in the network without exceeding the quality and availability objectives of the individual links because of radio interference. One such vendor independent tool is Pathloss 4. This tool is probably one of the best tools for complex microwave design. It includes North American and ITU standards, different diversity schemes, diffraction and reflection multipath analysis, rain effects, interference analysis etc. To browse Academia. Skip to main content. Log In Sign Up. How to design a microwave link. Christian Muamba. Library of Congress. Printed and bound in the United States of America. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher. All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. Over the years these digital radio systems have evolved in terms of capacity and functionality to such an extent that they can now support all fixed and mobile data and voice applications along with associated transport protocols. Within the mobile backhaul arena, the majority of cell sites around the globe are connected within the access domain by point-to-point digital microwave radio systems. As advanced mobile broadband and VoIP technologies are deployed, there is no reason why microwave radio systems cannot continue to provide this vital connectivity into the operators transport backbone. Ten years later, the challenge in the industry is now how to upgrade radio networks to incorporate packet-based traffic, and the majority of the new material addresses this aspect. In this second edition, I have also updated the various reference standards and added further real-world examples and formulas so that this book can still be used as a handy reference guide for people designing and maintaining microwave radio systems from UHF up to the millimeter bands. It is my view that the problems in the industry result from a paradoxical mix of attitudes, in which one group feels microwave radio design is so well established as to be trivial, yet often is using outdated analog-based design methods, and another group believes that digital microwave systems are binary in nature and forgets that the RF carrier is still analog and therefore subject to all the adverse affects of a complex analog radio signal traveling in a constantly varying atmosphere and thus having to overcome all the adverse weather effects. A key purpose of this book is to provide a thorough and accurate treatment of the fundamental principles of microwave transmission, which have been forgotten over the years, together with a fully updated approach to what happens in the real world in modern digital radio systems using the latest radio equipment. I am grateful to the various microwave manufacturers who have provided white papers that have technically supported the new material that I have written. Included in this list are Harris Stratex Inc. I would also like to thank Eskom, Andrew Antennas, Alcatel, and Microflect for the material that is still relevant from the first edition. I thank Andy Sutton from France Telecom, Orange group, for various useful discussions and for writing the foreword of the book. Lastly, I thank my son Sean for the excellent new diagrams he has produced for this new edition of the book. The requirement to backhaul mobile radio traffic quickly and reliably led to exponen- tial growth of this industry before the turn of the twenty-first century. It is often predicted that fiber optic transmission will stunt this growth. This phenomenal growth is set with the backdrop of an industry that still uses outdated design rules that are adapted from the old analog systems without understanding the impact on deployment costs or performance degradation. There is also growing public resistance to more radio sites being established, together with additional physical structures, such as wind farms that can potentially interfere with the microwave line-of-sight conditions, and these factors will force a more pragmatic approach to be adopted in order to get links to work reliably in nonideal conditions. Umts transmission link planning tool for excel rf cafe telecom knowledge and experience sharing fdd lte radio link telecom knowledge and experience sharing fdd lte radio link umts transmission link planning tool for excel rf cafe umts transmission link planning tool for excel rf cafe rf budget calculator link. Telecom knowledge and experience sharing fdd lte radio link simplified microwave link budget you simplified microwave link budget you noise temperature figure and factor noise temperature figure and factor excel sheet to estimate range for indoor and outdoor sub 1. Your email address will not be published. Notify me of follow-up comments by email. Notify me of new posts by email. Lte Link Budget Spread Sheet. Satellite Link Budget Calculator. Link Budget Calculator. Microwaves Area. Pegasus Configurator Lakeford Limited. Rf Budget Calculator Link. Hdpath Vhf Uhf Link Budget. Simplified Microwave Link Budget You. Noise Temperature Figure And Factor. Leave a Reply Cancel reply Your email address will not be published. What is Microwave Communication A communication system that utilizes the radio frequency band spanning 2 to 60 GHz. Small capacity systems generally employ the frequencies less than 3 GHz while medium and large capacity systems utilize frequencies ranging from 3 to 15 GHz. Advantages of Microwave Radio Less affected by natural calamities Less prone to accidental damage Links across mountains and rivers are more economically feasible Single point installation and maintenance Single point security They are quickly deployed 4. Line-of-Sight Considerations Microwave radio communication requires a clear line-of-sight LOS condition Under normal atmospheric conditions, the radio horizon is around 30 percent beyond the optical horizon Radio LOS takes into account the concept of Fresnel ellipsoids and their clearance criteria. Fresnel Zone - Areas of constructive and destructive interference created when electromagnetic wave propagation in free space is reflected multipath or diffracted as the wave intersects obstacles. Fresnel zones are specified employing ordinal numbers that correspond to the number of half wavelength multiples that represent the difference in radio wave propagation path from the direct path The Fresnel Zone must be clear of all obstructions. Microwave Link Design Process The whole process is iterative and may go through many redesign phases before the required quality and availability are achieved Interference analysis. Frequency Planning Rain attenuation Diffractionrefraction losses Multipath propagation Miscellaneous other losses unpredictable and sporadic in character like fog, moving objects crossing the path, poor equipment installation and less than perfect antenna alignment etc This contribution is not calculated but is considered in the planning process as an additional loss One method of calculation is based on knife edge approximation. Gas absorption Primarily due to the water vapor and oxygen in the atmosphere in the radio relay region. The absorption peaks are located around 23GHz for water molecules and 50 to 70 GHz for oxygen molecules. Gas attenuation versus frequency Total specific gas attenuation 23GHz 1. Attenuation due to precipitation Rain attenuation is the main contributor in the frequency range used by commercial radio links Rain attenuation increases exponentially with rain intensity The percentage of time for which a given rain intensity is attained or exceeded is available for 15 different rain zones covering the entire earths surface The specific attenuation of rain is dependent on many parameters such as the form and size of distribution of the raindrops, polarization, rain intensity and frequency Horizontal polarization gives more rain attenuation than vertical polarization Rain attenuation increases with frequency and becomes a major contributor in the frequency bands above 10 GHz The contribution due to rain attenuation is not included in the link budget and is used only in the calculation of rain fading Ground Reflection Reflection on the Earths surface may give rise to multipath propagation The direct ray at the receiver may interfered with by the ground-reflected ray and the reflection loss can be significant Since the refraction properties of the atmosphere are constantly changing the reflection loss varies. The loss due to reflection on the ground is dependent on the total reflection coefficient of the ground and the phase shift The highest value of signal strength is o obtained for a phase angle of 0 and the lowest value is for a phase angle of o The reflection coefficient is dependent on the frequency, grazing angle angle between the ray beam and the horizontal planepolarization and ground properties The grazing angle of radio-relay paths is very small usually less than 1o It is recommended to avoid ground reflection by shielding the path against the indirect ray The contribution resulting from reflection loss is not automatically included in the link budget. When reflection cannot be avoided, the fade margin may be adjusted by including this contribution as additional loss in the link budget Link Budget The link budget is a calculation involving the gain and loss factors associated with the antennas, transmitters, transmission lines and propagation environment, to determine the maximum distance at which a transmitter and receiver can successfully operate The gains from the antenna at each end are added to the system gain larger antennas provide a higher gain. The free space loss of the radio signal is subtracted. The longer the link the higher the loss. These calculations give the fade margin. In most cases since the same duplex radio setup is applied to both stations the calculation of the received signal level is independent of 27 direction. The fade margin is calculated with respect to the receiver threshold level for a given bit-error rate BER. The radio can handle anything that affects the radio signal within the fade margin but if it is exceeded, then the link could go down and therefore become unavailable In new generation microwave radios with power forward error correction schemes this difference is 0. Four fading types are considered while planning links. They are all dependent on path length and are estimated as the probability of exceeding a given calculated fade margin Multipath fading - Flat fading - Frequency-selective fading Rain fading Refraction-diffraction fading k-type fading. Multipath Fading is the dominant fading mechanism for frequencies lower than 10GHz. A reflected wave causes a multipath, i. vitoschikdai.pw —The global toolkit for microwave network design

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