WO2009088475A1 - Procédé et appareil pour configurer une antenne d'émission universelle à utiliser sur un satellite de réserve dans un système à multiples satellites - Google Patents

Procédé et appareil pour configurer une antenne d'émission universelle à utiliser sur un satellite de réserve dans un système à multiples satellites Download PDF

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WO2009088475A1
WO2009088475A1 PCT/US2008/014122 US2008014122W WO2009088475A1 WO 2009088475 A1 WO2009088475 A1 WO 2009088475A1 US 2008014122 W US2008014122 W US 2008014122W WO 2009088475 A1 WO2009088475 A1 WO 2009088475A1
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satellite
availability
antenna
locations
satellites
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English (en)
Inventor
Derek De Bastos
Duy Nguyen
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XM Satellite Radio Inc
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XM Satellite Radio Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/28—Adaptation for use in or on aircraft, missiles, satellites, or balloons
    • H01Q1/288—Satellite antennas

Definitions

  • the present invention is directed to satellite transmit antenna analysis, design and optimization. More particularly, the present invention is directed to a system for and method of optimizing and configuring a universal antenna for use on a spare satellite for any satellite in a multiple satellite system. Further, the present invention is directed to a system for and method of optimizing and configuring a universal antenna for use on a spare satellite for any plural deployed satellites that use spatial diversity transmission techniques to minimize outages at ground-based receivers and for which two or more antenna patterns projected from respective satellites have been jointly optimized.
  • Satellite radio broadcasting delivers 100 or more channels of audio content to ground-based stationary or mobile radio receivers that may be installed in vehicles such as cars, boats, and the like, or implemented as portable or non-portable radio receivers such as a receiver for use with a stereo receiver, or receiver embodied in a clock-radios or mobile telephone, and so on.
  • One implementation for a broadcast segment of a satellite radio system comprises two geostationary satellites at 85° and 115° West longitude orbital locations. In these orbits, virtually every location in the contiguous United States (CONTJS) has a direct view of both satellites.
  • CONTJS contiguous United States
  • the spare satellite To ensure continuous service in an event of an in-orbit anomaly and future service expansion, a third satellite (hereinafter referred to as the spare satellite) is needed.
  • the spare satellite would be equipped with a transmit antenna that is optimized for launch and use in the orbital location of the particular satellite to be replaced.
  • the economic factor is prohibitively high since at least two sets of antennas must be constructed simultaneously to provide a spare for both of the orbital locations (e.g., 85° and 1 15° West longitude) and, even if the construction cost is affordable, construction time may not be sufficiently fast to meet the necessary launch schedule.
  • any spare satellite that is to be stored "in-orbit" (versus a spare to be stored "on ground”) requires an antenna configuration that is capable of supporting both orbital positions.
  • the antenna pattern of the universal antenna is shaped, tuned or adjusted to provide uniform high availability to terrestrial radio receivers, when deployed on the replacement satellite and used in conjunction with a jointly optimized satellite, without wasting power where it is not needed.
  • method for optimizing an antenna pattern for a universal antenna to replace either of first and second antennas on respective ones of first and second satellites that have been deployed in first and second orbital positions and configured to operate in conjunction with each other to deliver signals to each of a plurality of receivers in a selected geographic coverage area having differing line of sight elevation angles to each of the first and second satellites.
  • the method comprises (1) determining, for each of a plurality of reference locations in the selected geographic coverage area, an initial performance value; (2) determining a population weighted average availability using first and second availability waterfall curves that indicate population served by a given level of link availability for respective ones of the first and second orbital positions, the population weighted average availability for respective ones of the first and second orbital positions being a first selected availability requirement and a second selected availability requirement, respectively; (3) determining if the performance value set for at least one of the plurality of reference locations does not achieve one of a selected range, a selected maximum value or a selected minimum value; (4) if the performance value does not achieve one of a selected range, a selected maximum value or a selected minimum value, then selecting a different performance value; (5) if the performance value does achieve one of a selected range, a selected maximum value or a selected minimum value, then determining if the availability for the at least one of the plurality of reference locations meets the first selected availability requirement for the first orbital position, and meets the second selected availability requirement for
  • the first and second satellites have been optimized to each have a selected availability to achieve a selected performance value in the selected geographic coverage area.
  • Determining the performance value for each of the plurality of reference locations comprises determining the maximum of the two performance values selected for the jointly optimized first satellite and the second satellite and at least initially setting the performance value of the universal antenna to the maximum performance value.
  • one of a selected range, a selected maximum value or a selected minimum value is selected to achieve link margin sufficient to close a communication link at that one of the plurality of reference locations when the universal antenna is deployed on a satellite in the farthest one of the first and second orbital positions.
  • the performance value is based on power flux density required to achieve the selected link margin and availability at each of the plurality of locations in the selected geographic coverage area using the extended empirical roadside shadowing (EERS) model for defining a relationship between elevation angle and required margin.
  • EERS extended empirical roadside shadowing
  • the method further comprises: (7) selecting different performance values for the universal antenna until predetermined criteria are met, the predetermined criteria comprising the performance value set for the universal antenna at each of the plurality of locations achieves one of a selected range, a selected maximum value or a selected minimum value, the availability for the universal antenna meets the first selected availability requirement and the second selected availability requirement for a selected number of the plurality of locations; (8) storing the selected different performance values for the universal antenna as the power requirements for the universal antenna; and (9) employing the determined power requirements to configure the universal antenna.
  • Fig. 1 illustrates the predicted baseline satellite system availability using conventional, jointly optimized transmit antenna patterns of two satellites in a conventional multiple satellite system
  • Fig. 2 illustrates the predicted satellite system availability using an optimized antenna per Fig. 1 with a universal antenna configured in accordance with an embodiment of the present invention
  • FIGS. 3 and 4 show, respectively, the elevation angles for two satellites positioned at 115° West and 85° West in an illustrative conventional multiple satellite system
  • FIG. 5 is a graph depicting the conventional extended empirical roadside shadowing (EERS) model relationship between elevation angle and required margin for several levels of availability;
  • FIG. 6 is a schematic diagram of known sample locations in the contiguous United States
  • FIG. 7 is a flow chart of a conventional implementation for jointly optimizing the transmit antenna patterns of two satellites in a conventional multiple satellite system
  • FIG. 8 is a graph illustrating the predicted EERS availability for two satellites in a conventional illustrative multiple satellite system
  • FIG. 9 depicts the achieved link margin for two satellites in a conventional illustrative multiple satellite system at various locations across the
  • FIGS. 10 and 11 show the respective power flux density for the two satellites positioned at 115° West and 85° West in the illustrative conventional multiple satellite system
  • FIGS. 12 and 13 show, respectively, the predicted single satellite
  • FIG. 14 shows the predicted combined availability for a two-satellite system for the two satellites positioned at 115° West and 85° West in the illustrative conventional multiple satellite system;
  • FIG. 15 depicts a simplified example of the process of Fig. 7 for a single location and two satellites in the illustrative conventional multiple satellite system;
  • Fig. 16 is a flow chart of a series of operations for optimizing a universal antenna in accordance with an exemplary embodiment of the present invention.
  • Fig. 17 is a matrix of data representing performance values achieved at each of a plurality of locations that is modified on a cell-by-cell basis to configure the requirements of a universal antenna based on a population-weighted metric in accordance with an exemplary embodiment of the present invention
  • 18 and 19 are, respectively, a graph and corresponding table, in accordance with an exemplary embodiment of the present invention, that provide availability versus population data for each of a baseline configuration involving two satellites with jointly optimized antennas for their respective orbital positions, a spare satellite in a first orbital position with antenna jointly optimized for a different (e.g., second) orbital position in a multiple satellite system, and a spare satellite in the second orbital position with antenna jointly optimized for the first orbital position in the multiple satellite system; and
  • Figs. 20 and 21 are, respectively, a graph and corresponding table, in accordance with an exemplary embodiment of the present invention, that provide availability versus population data for each of a baseline configuration involving two satellites with jointly optimized antennas for their respective orbital positions, a spare satellite with universal antenna designed in accordance with an embodiment of the present invention and deployed to replace a satellite at a first orbital position in a multiple satellite system, and another spare satellite with universal antenna deployed to replace a satellite at a second orbital position in the multiple satellite system.
  • the same drawing reference numerals will be understood to refer to the same elements, features, and structures. Detailed Description Of The Exemplary Embodiments
  • a system for designing and configuring a transmit antenna, hereinafter referred to as a universal antenna, prior to deployment on a spare satellite that can replace any one satellite from all the satellites in a multiple satellite system.
  • the multiple satellite system is a broadcasting system that employs spatial diversity using at least two satellites positioned at 85° and 115° West longitude, respectively, to cover the contiguous United States with a selected degree of availability.
  • the universal antenna configured in accordance with the exemplary embodiments of the present invention can be used as a spare satellite in other types of multiple satellite systems besides a satellite radio broadcasting system such as a mobile communications satellite system or satellite systems that can provide position determination (e.g., Global Positioning System (GPS)) or paging services.
  • GPS Global Positioning System
  • the universal antenna configured in accordance with exemplary embodiments of the present invention can produce a near-equal effective-isotropic- radiated-power (EIRP) pattern, independent of the orbital location in which the satellite is positioned, particularly when employed on a replacement satellite for a geostationary satellite.
  • EIRP effective-isotropic- radiated-power
  • the universal antenna operates as a cost-effective in-orbit or ground spare satellite since the universal antenna can be positioned at either satellite location, thereby saving in capital investment and in time to construct the spare satellite.
  • Predicted combined availability due to the spare satellite and one satellite having an optimized antenna is comparable to that achieved when optimized antennas are employed in both satellites for use in respective orbital locations, as described below in connection with Figs. 20 and 21.
  • calculated availability of the afore-mentioned existing satellite system i.e., the satellite broadcast system employing spatial diversity with two satellites positioned at 85° West and 115° West
  • FIG. 2 The predicted satellite system availability with one of the two satellites being replaced by the universal antenna is shown in Fig. 2.
  • the system availability when the universal antenna is used as a spare is reduced by less than 1.0% within the contiguous United States (CONUS).
  • CONUS contiguous United States
  • FIGS. 3 and 4 show, respectively, the elevation angles for satellites located at 115° and 85° West longitude, respectively. From these figures, it is apparent that radio receivers in different regions of the United States will have differing line of sight (LOS) elevation angles to each of the two satellites. As a result, and in view of fading due to foliage, for example, different standing link margins are required to maintain a predetermined level of availability.
  • LOS line of sight
  • FIG. 5 is a graph depicting the EERS model relationship between elevation angle and required margin.
  • the EERS model provides estimates of cumulative fade distributions due to roadside trees (i.e., foliage) within the following parameters: UHF (870 MHz) through S-Band (3 GHz), elevation angles to the satellite from 20° to 60° and percentages of outage from 1% to 20%.
  • UHF 870 MHz
  • S-Band 3 GHz
  • This well-known model is recommended by the International Telecommunications Union Radio Communication Section (ITU-R) (1994). Based on this model, it is possible to calculate a required link margin with respect to an elevation angle for desired levels of availability. These relationships are shown in the graph of FIG. 5. Thus, for example, in order to attain a 99% availability, it is necessary to have a link margin of approximately 33 dB where there is a 20° elevation angle to the satellite.
  • FIG. 6 is a schematic diagram of sample locations in the United States at which the EERS model was applied. Using this model, it is possible to determine the required transmit power flux density (PFD) to achieve the desired link margin and availability at each of the pre-selected regions, locations or points.
  • PFD transmit power flux density
  • the power requirement for the universal antenna at a location is set to meet selected criterion such as (1) to be within a selected range of performance values (e.g., EIRP), as well as (2) to achieve a desired availability based on respective curves representing population versus availability for satellites at each of at least two elevation angles that is less than an optimal baseline curve, as described below in connection with FIGS. 16-18.
  • selected criterion such as (1) to be within a selected range of performance values (e.g., EIRP), as well as (2) to achieve a desired availability based on respective curves representing population versus availability for satellites at each of at least two elevation angles that is less than an optimal baseline curve, as described below in connection with FIGS. 16-18.
  • the transmit PFD for the universal antenna can be redistributed from the transmit PFD or performance values (e.g., EIRP) among other locations having lower population and/or lower intrinsic fading probability.
  • the EERS model was chosen since it is one of the more well-accepted predictive modeling standards by those skilled in the art. Then, at step 504, the initial required transmit PFD of each satellite at a number of locations within the desired coverage area (e.g., those shown in FIG. 5) is determined based on the desired margin to achieve a given availability. [0044] The availability goal for a single satellite is preferably given by
  • Av SAT1 1 - square root(l- AV BOTH )
  • This formula applies only for two satellites where the outages of one are statistically independent of the other.
  • Other formulas to determine the individual satellite availability when a goal for both (or all in the case of more than two satellites) may also be used provided that a mathematical relationship of some kind can be assumed between the individual availability and the joint or combined availability for the group of satellites.
  • the Margin (M) required to achieve the desired availability (Av) can be determined using the EERS model as a function of elevation angle ( ⁇ ), using the following formula:
  • M(Av, ⁇ /L)) ⁇ (Av) + ⁇ (Av) ⁇ + ⁇ (Av) ⁇ 2
  • the process for jointly optimizing antennas ends and the antennas are deemed to be optimized in accordance with the desired goals, e.g., 99% availability.
  • the process continues with step 508 at which it is determined if all possible PFD requirement combinations have been tested or analyzed.
  • step 510 the power requirement for the incapable satellite's antenna is reduced.
  • step 512 the PFD requirement is increased for the antenna on the other satellite for the same location.
  • the process then returns to step 506 to determine whether the combined availability for both satellites meets the desired availability, e.g. 99%.
  • the process for jointly optimizing antennas continues until it is no longer feasible to decrease or increase the required PFD on a given satellite and make the opposite adjustment on the other satellite. More specifically, at step 508, it is determined whether there are any remaining combinations of required PFD for a given location to analyze.
  • step 514 the PFD requirement is decreased for both satellites at the location being analyzed. Reduction of the PFD requirement for both satellites is preferably reserved for locations that are less populated, have relatively less susceptibility to fading due to foliage and/or are deemed to be commercially less important and thus can be sacrificed in order to provide better availability to other location or regions.
  • FIG. 8 is a graph illustrating the predicted EERS availability for two satellites. Uniform high availability can be achieved by matching over-performing regions (e.g., better than 90%) on one satellite with under-performing regions (e.g., below 90%) on the other satellite.
  • FIG. 9 depicts the achieved link margin for two satellites with jointly optimized antennas in accordance with FIG. 7 at various locations across the United States, corresponding to the predicted EERS availability of FIG. 6.
  • FIGS. 10 and 11 show the respective power flux density of satellites at 115° and 85° West longitude.
  • FIGS. 12 and 13 show, respectively, the predicted single satellite EERS availability for the two satellites.
  • FIG. 15 depicts an exemplary iterative process for availability optimization for a two-satellite system with jointly optimized antennas per FIG. 7.
  • 90% availability is desired from both satellites, then, assuming a maximum EIRP limit of 66 dBW, the second satellite's EIRP is unrealizable.
  • the first satellites desired availability is increased to 95% and the second satellite's desired availability is decreased to 80%, then the first satellite's EIRP is unrealizable. Accordingly, the first satellite's desired availability is decreased slightly to 94% and the second satellite's desired availability is increased to 83%, whereby a realizable solution is achieved.
  • one or more availability "waterfall" curves are selected for use when configuring a universal antenna that can be deployed on a replacement satellite for either of two or more satellites in a multiple satellite system that have jointly optimized antennas (e.g., per FIG. 7).
  • Fig. 20 depicts a baseline availability curve showing availability (%) relative to population for a satellite employing two jointly optimized antennas.
  • 100 % availability is achieved for 100 % of the population for the area served by the satellite constellation (e.g., the contiguous United States served by the two spatially diverse satellites in the illustrated embodiments).
  • a satellite is configured to provide, for example, approximately 99% availability to 95% of the population. It is desirable to maximize the area under the availability curve.
  • an iterative process of allocating system resources (e.g., performance, link margin) among a selected number of representative points in the intended geographic coverage or service area in accordance with an exemplary embodiment of the present invention seeks to maximize the area under the selected availability waterfall curve (e.g., Fig. 20).
  • At least one maximum availability waterfall graph such as Fig. 20 is used for designing the universal antenna regardless of the orbital position to which the replacement satellite having the universal antenna is deployed.
  • Fig. 20 also depicts respective curves showing population versus availability depending on the orbital position to which the replacement satellite having the universal antenna is deployed.
  • FIG. 20 provides two other curves besides the baseline curve for a replacement satellite with universal antenna being deployed at respective ones of the satellites at 115° and 85° West longitude and indicated at Universal SAT A and Universal SAT B.
  • a population weighted average availability is determined for each of the three curves depicted in FIG. 20.
  • FIGs. 20 and 21 provide population versus availability data for the baseline and two other configurations (i.e., a baseline configuration involving two satellites with jointly optimized antennas for their respective orbital positions in a multiple satellite system, a spare satellite in a first orbital position with antenna jointly optimized for a different (e.g., second) orbital position in the multiple satellite system, and a spare satellite in the second orbital position with antenna jointly optimized for the first orbital position in the multiple satellite system).
  • a method for configuring a universal antenna in accordance with an exemplary embodiment of the present invention preferably commences with selecting an objective model that can predict link margins based on elevation angles, power, foliage (fading), and so on.
  • the EERS model is preferably used since it is one of the more well-accepted predictive modeling standards by those skilled in the art.
  • the initial required transmit PFD of each satellite at a number of locations within the desired coverage area is determined based on the desired margin to achieve a given availability determined via the EERS model.
  • the initial transmit PFD can be the transmit PFD of each satellite having a jointly optimized antenna determined via the iterative process shown in FIG. 7.
  • a subset of representative latitude and longitude points e.g., N geographic points or locations where N is a selected integer number
  • N of the sample locations depicted in Fig. 6 are preferably selected for determining if selected performance and availability criteria are met to configure the universal antenna in accordance with FIG. 16.
  • the sample locations are reference points within the CONUS in the illustrated example and are each characterized by certain attributes such as population, elevation angles to satellites in each of the orbital positions, and relative importance. Relative importance of the reference points is not necessarily based on population but can be based on desired customer base in the region surrounding the sample location, or desired continuity of coverage within that region relative to adjacent regions, and so on.
  • a matrix of data relating to these N reference points is preferably created for determining, storing and updating data (e.g., data relating to system resources allocated among the N points) during the iterative process of FIG. 16 to design a universal antenna that can be used on a replacement satellite in any of two or more orbital positions in a multiple satellite system.
  • the data for the universal antenna preferably comprises at least performance data (e.g., EIRP) determined using the iterative process illustrated in FIG. 16.
  • the matrix can comprise additional data as well, such as population census data, relative importance and the like for each of the N sample locations or reference locations.
  • the performance e.g., link margin expressed as EIRP
  • the performance is initially set at the larger of the performance data for each of the satellites having a jointly optimized antenna (step 1606) such as that determined in accordance with FIG. 7.
  • an iterative process commences. First, it is determined whether the satellite with universal antenna can achieve the performance for a selected one of the locations (step 1608).
  • the selected location can be the first of the N locations, that is, the first row in the matrix of FIG. 17, and the iterative process can continue on through to the following consecutive locations.
  • the iterative process can commence using a location having the largest corresponding population or greatest relative importance, and the iterative process can continue through all or a subset of the remaining locations in the order of locations having the largest corresponding populations to the smallest populations or greatest relative importance to least relative importance.
  • the performance value initially set for the satellite with universal antenna may be outside a selected range or beyond a selected maximum or minimum EERP limit similar to the EERP limit used above in connection with FIG. 15.
  • the performance value can be determined to be insufficient to close on communication, that is, the link margin selected for the universal antenna can be insufficient to close on the communication link needed at the geographic location for a replacement satellite in the farthest orbital position.
  • the performance can be deemed to not have been achieved if a selected link margin is not sufficient to overcome the potential (i.e., probabilistic) link degradation due to foliage, for example, as determined using the EERS model for a specific location's elevation angle and PFD at that location.
  • some reference points may require allocation of as much as 10-12 dB margin to achieve performance for that location based on elevation angle and optionally other selected factors such as relative importance with respect to other reference points.
  • Performance or system resources are allocated among the selected reference points in the matrix to achieve availability for preferably all orbital positions or elevation angles where a satellite with universal antenna may be deployed.
  • the iterative process of FIG. 16 can borrow resources allocated to this first point for allocation to another reference point, where performance and/or availability is not yet achieved, based on selected criteria such as relative importance without degrading the performance of the first reference point to an unacceptable level.
  • performance can be increased for other reference points were margin was previously deemed too low in step 1608.
  • some points may be considered to be of such little relative importance as to permit failure to achieve a selected performance at that location per step 1608 if other reference points of greater importance require those resources.
  • step 1614 (e.g., initially per step 1606 or via a prior iteration of step 1614) is realizable (e.g., can be achieved with sufficient link margin to close the communication link while taking selected losses and errors into consideration), then it is determined whether the waterfall curves (e.g., the two non-baseline curves in FIG. 20 and non-baseline entries in FIG. 21) for both of the Universal SAT A and Universal SAT B are satisfied (steps 1610 and 1612). For example, reference points characterized by lack of elevation angle relative to a satellite can be allocated more power to achieve a desired availability such as that provided in Figs. 20 and 21.
  • Two or more curves are preferably used since the different elevation angles of the potential two or more replacement satellite orbital positions can create different availability for a selected geographic location, in which case the satellite resources (e.g., PFD) need to be retasked or redistributed to optimally accommodate the populations of the different geographic locations.
  • the satellite resources e.g., PFD
  • the performance value set for the satellite with universal antenna is not realizable, or either of the waterfall curves for the Universal SAT A and Universal SAT B are not satisfied, then the performance value(s) are redistributed among the other locations or stations per (step 1614) preferably using a population-weighted metric or other metric such as relative importance.
  • the performance (e.g., EIRP) for the satellite with universal antenna can be increased or decreased for another location(s) or reference point(s), depending on its corresponding population or relative importance, to achieve the above-referenced criteria in steps 1608, 1610 and 1612, that is, that the performance value set for the satellite with universal antenna is realizable, and both of the waterfall curves for the Universal SAT A and Universal SAT B are satisfied.
  • the data for the satellite with universal antenna at the next location can be reviewed and changed per step 1614 until the universal satellite antenna data for last location in the matrix is analyzed and determined per step 1618.
  • the data for only a subset or selected ratio of the N sample locations needs to be determined to meet the criteria in steps 1608, 1610 and 1612. Further, the necessary criteria can be changed depending on the corresponding population (e.g., only a subset of the criteria needs to be met for locations in less densely populated areas) or relative importance, or additional different criteria can be imposed as the iterative process progresses. [0063] In view of the foregoing, the present invention makes it possible to optimize a spare satellite antenna pattern to be used on a replacement satellite for any of the satellites in the space-based broadcasting segment of a multiple satellite system.
  • the shape of the universal antenna can be implemented using known methods.
  • the universal antenna can be, for example, an offset-fed reflector having a nominal circular aperture.
  • the surface of the reflector is modified from its paraboloid shape such as to induce the appropriate current density and phasing.
  • a secondary shaped beam is created to match a selected geographic such has the CONUS.
  • the modified surface is expressed by a mathematical polynomial expression, of which all coefficients are continuously modified until a desired secondary beam is achieved, based for example on the universal antenna pattern developed using an iterative process as exemplified in FIG. 16.
  • extensive analytical analyses, using methods described herein demonstrate that the combined satellite availability, with one satellite using a universal antenna and one satellite uses a jointly optimized antenna, both as described herein with reference to FIGS. 16 and 7, respectively, does not degrade significantly.
  • the present invention is preferably implemented with software that is run on a general purpose computer. Of course, portions, or even all of the functionality described herein could also be implemented directly in electronic hardware.
  • the software can also be embodied as computer-readable codes on a computer-readable recording medium.
  • the computer-readable recording medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer-readable recording medium include, but are not limited to, read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves (such as data transmission through the Internet via wired or wireless transmission paths).
  • the computer-readable recording medium can also be distributed over network-coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion.
  • functional programs, codes, and code segments for accomplishing the present invention can be easily construed as within the scope of the invention by programmers skilled in the art to which the present invention pertains [0066]
  • the specification may have presented the method and/or process of the present invention as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible.

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Abstract

L'invention porte sur un système pour configurer une antenne d'émission universelle pour un satellite géostationnaire qui produit un diagramme de puissance isotrope rayonnée équivalente (EIRP) presque égale, indépendant de la position orbitale dans laquelle le satellite est positionné. Dans un système de diffusion par satellite employant une diversité spatiale avec deux satellites (par exemple, des satellites positionnés à 85° ouest et à 115° ouest), l'antenne universelle fonctionne sur un satellite de réserve en orbite d'une façon rentable car le satellite de réserve à antenne universelle peut être positionné à l'une ou l'autre position de satellite, permettant ainsi d'économiser sur l'investissement en capital et en temps pour construire le satellite de réserve. Une disponibilité combinée prédite due au satellite de réserve en orbite et à un satellite ayant une antenne optimisée est comparable à celle obtenue lorsque des antennes optimisées sont employées dans les deux satellites à utiliser dans des positions orbitales respectives.
PCT/US2008/014122 2007-12-31 2008-12-31 Procédé et appareil pour configurer une antenne d'émission universelle à utiliser sur un satellite de réserve dans un système à multiples satellites Ceased WO2009088475A1 (fr)

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CN112461512A (zh) * 2020-11-11 2021-03-09 北京空间机电研究所 一种大口径空间光学遥感器星上辐射定标方法及装置
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