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Proceedings of the IEEE

Issue 11 • Date Nov. 1984

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Displaying Results 1 - 25 of 32
  • [Front cover and table of contents]

    Publication Year: 1984 , Page(s): c1
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    Freely Available from IEEE
  • Scanning the issue

    Publication Year: 1984 , Page(s): 1427 - 1428
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  • Syncom and its successors

    Publication Year: 1984 , Page(s): 1429 - 1434
    Cited by:  Papers (1)
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    Twenty years ago, Syncom III transmitted the Tokyo Olympics to the United States. It was the first transoceanic television transmission for a sustained period of time. The success of Syncom led to the development of satellite systems for both international and domestic applications. The competition that ensued among domestic satellite systems has resulted in a number of innovative services, which are in many cases characterized by small terminals on user premises. Such systems avoid the cost of terrestrial communications systems and provide for greatest customer convenience. View full abstract»

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  • Satellite locations—1984

    Publication Year: 1984 , Page(s): 1434 - 1444
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    In a brief 20 years the number of satellites in the geosynchronous and geostationary orbits have increased by enormous bounds. Far more than Arthur C. Clarke, himself, could have anticipated two decades ago. This paper lists those satellites in geographical order, starting with the longitude of Greenwich and proceeding eastward, and the second table starting at Greenwich and going westward. The potential for additional growth in the number of geosynchronous and geostationary satellites still exists for tomorrow through new technologies being designed today. View full abstract»

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  • Satellite telenets: A techno-economic assessment of major trends for the future

    Publication Year: 1984 , Page(s): 1445 - 1456
    Cited by:  Papers (1)
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    This paper reviews the historical trends in the development of new communications satellite technology and the technical and economic forces that will drive a new revolution in wide-band communications services in the 1980s and 1990s. The following key technical and service aspects of the new satellite telenets of the 1980s and 1990s will be addressed: new digital services, new antenna designs, intersatellite links, on-board signal processing and regeneration, and new architectural and servicing concepts for long-lived satellites. The possibility of non-Clarke orbit communications satellites in the 21st century will also be reviewed. Competitive technical and economic trends in other forms of telecommunications technologies will also be explored, in order to establish some economic and service "figures of merit" for the future. This analysis reveals some exciting and unexpected aspects about the new satellite telenets of the late-twentieth and early-twenty- first centuries. If messages are beamed to and from communications satellites by laser, there would be room for so many channels that every person on Earth could have his own, just as he has his own telephone number. He could reach everyone on Earth with no trouble, transmitting sight as well as sound... It is not unlikely that a good beginning toward laser satellite communications may be made by the end of the century... If so, it will represent a remarkable advance, considering that at the beginning of the century, mankind was still tied to the wire. (Isaac Asimov, Science Past, Science Present. New York: Ace Books, 1975.) If you're willing to spend enough money on advanced electronics you can virtually guarantee they can be made to not work.--One of Augustine's Laws. ("Augustine's Laws and major systems development programs, pt. 2," Aeronautics and Astronautics, p. 49, Jan. 1981.) View full abstract»

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  • INTELSAT VI—A continuing evolution

    Publication Year: 1984 , Page(s): 1457 - 1468
    Cited by:  Papers (2)
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    In early 1982, the International Telecommunications Satellite Organization (INTELSAT) awarded a contract to the Hughes Aircraft Company for a new generation of communications satellites. The INTELSAT VI satellites are the largest, most sophisticated commercial communications satellites ever built. Their major technological challenges include a six-fold reuse of the 6/4-GHz frequency spectrum and the introduction of satellite-switched TDMA. The INTELSAT VI satellites are designed to become the backbone of the INTELSAT system in the late 1980s and early 1990s. View full abstract»

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  • Digital satellite networks in Europe

    Publication Year: 1984 , Page(s): 1469 - 1482
    Cited by:  Papers (2)  |  Patents (1)
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    Developments of digital satellite networks are progressing in Europe at international as well as national levels. EUTELSAT and its signatories are actively setting up two regional networks based on the ECS satellites built by ESA. One will carry large bundles of telephone circuits between national gateways; the other will provide special services to corporate organizations and businesses. On the other hand, several countries are implementing or planning their own national networks, all for small-station services. These are France with Telecom 1, Sweden with TELE-X, Norway with NORSAT II, Italy with ITALSAT, the Federal Republic of Germany with DFS/Copernicus, and the United Kingdom with UNISAT. These projects are described here and their characteristics compared. The paper brings out the great diversity in the approaches, as illustrated by Telecom 1 where the accent is on the development of an ISDN, TELE-X where it is on the low cost of user stations, and ITALSAT on the flexibility of the network. View full abstract»

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  • RCA satellite networks: High technology and low user cost

    Publication Year: 1984 , Page(s): 1483 - 1505
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    Channel demands on the RCA Americom domestic satellite communications system have continued to increase rapidly since the first launch in 1975. After deploying four of the first-generation 24-channel spacecraft, Americom introduced an advanced, all-solid-state design in 1982 which has more than twice the traffic capacity of the original series. To supplement the operational network of six C-band satellites, K-band satellites will be introduced in 1985 to serve the "small master-antenna TV market and digital satellite networks. Accompanying the continuous incorporation of state-of-the-art technology into successive satellites to achieve increased traffic capacity and longer life, new terrestrial equipment and efficient signal processing/modulation techniques are being exploited to continue the competitive reduction of cost per satellite Circuit per year. View full abstract»

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  • Satellite communications networks

    Publication Year: 1984 , Page(s): 1506 - 1519
    Cited by:  Papers (2)  |  Patents (1)
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    The evolution of satellite communication systems over the past two decades from simple point-to-point links with unique subcarrier-defined paths between points to today's multipoint, satellite-switched, multi-satellite networks tying together hundreds of earth stations, and transmitting voice and data increasingly in the time domain is considered. Examples of the methods used to manage network resources efficiently through terrestrial control and monitoring of information flow together with on-board switching are given. These examples are choosen mostly from the INTELSAT experience which will soon include a sixth generation of space segment. The paper concludes with a discussion of the future directions of satellite network development made possible by the technology being planned for NASA's Advanced Communications Technology Satellite. This design anticipates the needs of both high-volume trunking and thin-route service. View full abstract»

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  • The emergence of satellite systems for rural communications

    Publication Year: 1984 , Page(s): 1520 - 1525
    Cited by:  Papers (2)
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    Technology improvements in recent years are leading toward low-cost satellite communications systems that can be applied to rural telephony solutions worldwide. This paper will review some of the key technology and economic developments that are taking place today and further developments projected for the near future that can make this prospect a reality. Advances in signal processing and error-correction techniques have enabled more efficient use of space segment. In parallel, the trend of higher power, higher frequency satellites is causing dramatic reductions in size and cost of corresponding ground segment earth terminals. Coupled with these developments will be intelligent on-board switched satellite processors which can provide added network flexibility and further reduce overall system costs. Candidate systems, technology, and economic analyses will be discussed to demonstrate the feasibility of these services for both telephony and data, as well as a projected time schedule when they may be achieved. View full abstract»

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  • Micro earth stations as personal computer accessories

    Publication Year: 1984 , Page(s): 1526 - 1531
    Cited by:  Papers (13)  |  Patents (3)
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    Equatorial Communications Company has shipped more than 15000 micro earth stations, typically 24 in (60 cm) in diameter and costing under $3000 for reception of satellite data transmission. Many are used as data input devices for personal computers in distributed database applications. Equatorial is also developing low-cost interactive micro earth stations appropriate for connecting personal computers or terminals to remote host computers. Equatorial is also a satellite transponder owner and provider of packet-switched satellite network services to the installed base of micro earth stations. Spread-spectrum modulation techniques implemented in microprocessor technology are used in Equatorial networks and earth stations to provide high performance, including interference rejection, at very low cost. View full abstract»

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  • PACKSATNET—An alternative to data networks

    Publication Year: 1984 , Page(s): 1532 - 1536
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    This paper contains a presentation of PACKSATNET, the demonstration data network of Indonesia based on the PALAPA satellite [1] that uses only radio links from the user's premises. PACKSATNET is scheduled to go into operation before the end of 1984, so it is already possible to draw some conclusions about its development phase and to point out its possible expansion into a public data network, taking into account the existing network, technological progress, and the growth of data communication needs. View full abstract»

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  • Improvements in capacity of analog voice multiplex systems carried by satellite

    Publication Year: 1984 , Page(s): 1537 - 1547
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    Significant improvements in the voice capacities of satellite transponders have been made in the last few years. A major emphasis has been in improving the voice channel capacities of TDMA using techniques such as ADPCM and DSI. In domestic satellite systems, however, analog transmission of speech signals continues to be used heavily. This paper describes how the capacity of analog FDM-based systems has been improving in the last decade. The capacity improvements are made possible by the use of syllabic compandors. Using compandors, the capacity of a transponder can be increased by nearly threefold if the RF modulation is FM, and can be increased by sixfold if the RF modulation is SSB-AM. The latter is made possible by the availability of more linear satellite amplifiers and the realization that the average speech volumes are much lower than what are traditionally assumed. View full abstract»

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  • Analytical comparisons of CSSB and TDMA/DSI satellite transmission and techniques

    Publication Year: 1984 , Page(s): 1548 - 1555
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    At the same time that Time-Division Multiple Access (TDMA) with Digital Speech Interpolation (DSI) is gaining wide acceptance, being planned for almost every modern satellite communication network as the basic transmission technique, a variation of the classical single sideband using companders (CSSB) has recently been proposed, accompanied by the claim of higher transponder capacities. The higher capacity of CSSB is supported under a variety of assumptions (lower speech levels, increased transponder linearity, benign interference environment) that hinders the comparison of CSSB with other well-established satellite transmission techniques such as FDM/FM or TDM/D51. The purpose of this paper is to "normalize" CSSB to a common set of assumptions that permits its capacity to be calculated on the same bases that apply to other satellite transmission methods, and in this manner to identify the ranges of ground and space segment parameters that would render CSSB superior to existing alternatives. In particular, CSSB is compared with TDMA/DSI, using analytical approaches that permit the simultaneous consideration of the principal factors involved in the capacity of both systems. These factors are • speech and compander characteristics • ground segment parameters, G/T, and antenna sidelobe radiation • space segment parameters, in particular EIRP, the transponder nonlinearities, and orbital spacing. These factors have been quantified for a typical 36-MHz C-band transponder with EIRP--34 dBW. The results show that CSSB's claims of higher capacity are realizable only under idealized transponder characteristics or with larger ground segment antenna sizes. In addition, CSSB's performance degrades faster than TDMA/DSI under fading conditions, suggesting that margins must be subsequently improved for this technique. View full abstract»

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  • Cost-effective networking via digital satellite communications

    Publication Year: 1984 , Page(s): 1556 - 1563
    Cited by:  Papers (3)  |  Patents (3)
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    This paper presents the major issues in forming a cost-effective and efficient network from a set of earth stations sharing the satellite resource. The discussion is in the context of satisfying the performance requirements for transmission of data, voice, and image presented to earth stations in digital form. Multiple access techniques have significant impacts on the network economy. Although wide-band single-carrier time-division multiple access (TDMA) uses the satellite capacity efficiently and is cost-effective for networks with large traffic volumes per node, it requires expensive earth stations and is not cost-effective for networks with small traffic volumes per node. The concept of multicarrier-TDMA (MC-TDMA) is described and its economic advantage over TDMA is demonstrated for networks with dispersed points of traffic origination. Application of demand assignment to MC-TDMA is also presented. Some implementation issues are also discussed. View full abstract»

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  • Efficient space segment utilization in satellite data networks

    Publication Year: 1984 , Page(s): 1564 - 1572
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    A generalized approach to the efficient utilization of the space segment in multicarrier per transponder applications is presented. Based on the concept of normalized satellite link densities, the conditions required to fully utilize the available transponder resources (power and bandwidth) are derived. These conditions are applied to the design of satellite data networks comprising a large number of stations of various sizes. The design approach is based on the idea of determining the ground segment configuration that ensures that the satellite links to small earth stations (power-limited links) and those to large earth stations (bandwidth-limited links) are balanced in such a way, that both the transponder power and the bandwidth are fully utilized. An example of the design of a simple data network using this technique is shown. View full abstract»

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  • Multiple-access protocols for satellite packet communication networks: A performance comparison

    Publication Year: 1984 , Page(s): 1573 - 1582
    Cited by:  Papers (24)  |  Patents (2)
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    This paper considers satellite packet communication networks with a large population of bursty users and presents an analytic comparison of the throughput versus average message delay trade-off characteristics of multiple-access protocols. The following six multiple-access protocols are examined: 1) slotted ALOHA, 2) reservation-ALOHA, 3) a reservation protocol with a slotted ALOHA reservation channel, 4) a reservation protocol with a TDMA reservation channel, 5) SRUC (Split Reservation Upon Collision), and 6) fixed assigned TDMA. All the protocols are required to ensure that all packets of a message are correctly received in the proper order at the destination. Then, a unified presentation of the delay-throughput performance of the protocols is given by means of an analytical technique called equilibrium point analysis. The throughput versus average message delay tradeoff characteristics are compared taking into account the system stability. View full abstract»

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  • Performance of uplink random-access and downlink TDMA techniques for packet satellite networks

    Publication Year: 1984 , Page(s): 1583 - 1593
    Cited by:  Papers (6)
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    In this paper the integration of ALOHA random-access schemes and TDMA techniques in a multibeam packet satellite network are analyzed. The uplink channels operate according to a slotted-ALOHA protocol, while the downlink channels use a TDMA strategy. Two different models are described. In the first model, each transponder on-board the satellite is permanently connected to a preassigned spot beam. The second model uses a number of transponders lower than the number of spot beams. Some different strategies of transmission are proposed in the latter model, able to provide full interconnection among earth stations by channel-hopping capability of the transponders. The performance of the models is evaluated through queueing theory analysis and extensive computer simulations. The obtained results suggest the second model as an efficient candidate for the implementation of a multibeam packet satellite network. In that case, the system parameters must be carefully chosen in order to avoid possible instability conditions. View full abstract»

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  • SBS TDMA-DA system with VAC and DAC

    Publication Year: 1984 , Page(s): 1594 - 1610
    Cited by:  Papers (6)  |  Patents (14)
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    This paper describes many of the design considerations involved in developlng the demand assignment (DA) subsystem of the TDMA satellite communication system for Satellite Business Systems. Each earth station has a satellite communications controller (SCC) which requests capacity to meet current voice and data traffic demands. A central reference station frequently reallocates capacity based on the requests of all the earth stations in a network. To minimize the amount of satellite capacity required, the SCC has a circuit-switching capability for voice calls as well as for digital data calls. Furthermore, the SCC employs voice activity, compression (VAC) and data activity cornpression (DAC), In which the amount of capacity requested is based on measured average speech activity as well as the number of off-hook voice ports and the number of off-hook data ports. Data calls are queued on a first-come, first-served basis when capacity is not immediateiy available. The reference station distributes excess capacity according to a nonlinear table lookup procedure so that the voice call blocking probability is equalized across the network. The DA system makes much more efficient use of satellite transmission capacity than a design with fixed-capacity trunk routes. View full abstract»

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  • An integrated voice and data multiple-access scheme for a land-mobile satellite system

    Publication Year: 1984 , Page(s): 1611 - 1619
    Cited by:  Papers (20)
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    A Land-Mobile Satellite System (LMSS) is a satellite-based communications network which provides voice and data communications to mobile users in a vast geographical area. By placing a "relay tower" at a height of 22300 mi, an LMSS can provide ubiquitous radio communication to vehicles roaming in remote or thinly populated area. LMSS is capable of supporting a variety of services, such as two-way alphanumeric service, paging service, full-duplex voice service, and half-duplex dispatch service. A Network Management Center (NMC) will handle the channel requests, channel assignments, and in general the network control functions. A pool of channels is managed at the NMC to be shared by all mobile users. An integrated demand-assigned multiple-access protocol has been developed for the experimental LMSS. The pool of channels is divided into reservation channels and information channels. The information channels can be assigned by the NMC to be either voice channels or data channels. Each mobile user must send a request through one of the reservation channels to the NMC via the ALOHA random-access scheme. Once the request is received and processed, the NMC will examine the current traffic condition and assign an information channel to the user. NMC will periodically update the partitions between the reservation channels, voice channels, and data channels to optimize system performance. Data channel requests are queued at the NMC while voice channel requests are blocked calls cleared. Various operational scenarios have been investigated. Tradeoffs between the data and voice users for a given delay requirement and a given voice call blocking probability have been studied. In addition, performance impacts of such technological advancements as satellite on-board switching and variable bandwidth assignment are discussed. View full abstract»

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  • A digital transmission system for global maritime satellite communications

    Publication Year: 1984 , Page(s): 1620 - 1626
    Cited by:  Papers (2)
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    A digital transmission system for global maritime satellite communications has been designed, and experimental communications equipment has been developed, taking account of its potential application to the INMARSAT system where analog modulation is currently used for telephone signal transmission. This paper discusses possible digital technologies to realize an efficient digital transmission system, and presents a concept for the designed system. The paper also describes the hardware configuration and the performance characteristics of the experimental equipment. View full abstract»

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  • Packet switching for mobile earth stations via low-orbit satellite network

    Publication Year: 1984 , Page(s): 1627 - 1636
    Cited by:  Papers (10)  |  Patents (16)
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    A potentially valuable implementation of a satellite computer communication packet switched network is one which is survivable and distributed. That is, a system which dynamically adapts to changing network element connectivities, changing interconnections of users, and is not dependent on any central unit for its own internal command and control. A laboratory prototype of such a system has been constructed of a group of computers which when given communication circuits between them will, acting autonomously, create a computer communication packet switching network and which will continually adapt to changes in connectivity. In this paper, an adaptive computer communication routing algorithm is described, its application in space including a space segment design is presented, its actual implementation in real physical hardware is discussed, and system performance results as parameters are varied are presented. View full abstract»

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  • 30/20-GHz domestic satellite communication system in the public communication network of Japan: Design and operation

    Publication Year: 1984 , Page(s): 1637 - 1644
    Cited by:  Papers (3)  |  Patents (1)
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    Nippon Telegraph and Telephone Public Corporation (NTT) initiated the world's first 30/20-GHz domestic satellite communication system for commercial use, using CS-2s launched from Japan in 1983. This system utilizes TDMA digital communication in the trunk transmission route of the public communication network, which includes interregional-center routes and main-island-to-remoteisland routes. Small transportable earth stations enable easy access to the public communication network from any place in Japan. The adoption of the 30/20-GHz band enables use of a compact on-board antenna that has a shaped beam that effectively covers the main islands of Japan. It also enables the use of high-performance, compact antennas at the earth stations. These antennas can easily be installed on the roof of telephone offices or set on motor vehicles. One apparent disadvantage of using the 30/20-GHz band is rain attenuation. However, NTT has realized a commercial system that is affected very little by rain attenuation. This was accomplished by utilizing high-performance radio equipment and by concentrating on appropriate system design. Adoption of the 30/20-GHz band is quite significant because the wide bandwidth available enables construction of high-capacity economical transmission systems. It also enables use of small antennas, which allow construction of high-speed digital direct-to-user transmission systems using small earth stations. These expand the application of the domestic satellite communication system to even small service areas. Therefore, NTT considers satellite communication to be of primary importance for its proposed digital communication network, and has begun research on a high-capacity, economical, multibeam communication satellite system using the 30/20-GHz band. This paper describes the 30/20-GHz band radio technology, digital communication technology utilizing high-speed TDMA, and operational technology in the public communication network. View full abstract»

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  • Complex eigenfrequencies of axisymmetric objects: Physical interpretation in terms of resonances

    Publication Year: 1984 , Page(s): 1652 - 1653
    Cited by:  Papers (1)
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    We calculate and compile complex eigenfrequencies of spheroids and finite-length cylinders for electromagnetic and acoustic vibrations. This includes eigenvibrations of nonlongitudinal type, studied by us earlier for the first time. We provide a physical explanation for these in terms of the resonances caused by the phase matching of helical surface waves on the object. View full abstract»

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  • Minimum p-error design of nonuniformly spaced linear array

    Publication Year: 1984 , Page(s): 1654 - 1655
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    A design method which minimizes the p-error of a weighted array pattern for nonuniform linear array is studied. The Fletcher-Powell method is used to find the minimum set of sensor locations. With uniform weight and large p, the result has sidelobes of almost equal level. In addition, an array pattern with null(s) at some specified value can be designed with proper choices of weights. View full abstract»

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