AU2020102827A4

AU2020102827A4 - IPCM- Movable Satellite: Intelligent Propagation Impairments for Movable Satellite Communication Links at The Microwave Frequencies in Location

Info

Publication number: AU2020102827A4
Application number: AU2020102827A
Authority: AU
Inventors: Prasad A. Y.; K. S. Ananda Kumar; R. Balakrishna; Sai Madhavi D.; Sumitha Manoj; Ch. Ram Mohan Reddy; Sougandhika Narayan; Shamshekar Patil; S. Vijayanand
Original assignee: A Y Prasad Dr; Ananda Kumar K S Dr; Balakrishna R Dr; Madhavi D Sai Dr; Manoj Sumitha Dr; Mohan Reddy Ch Ram Dr
Current assignee: A Y Prasad Dr; Ananda Kumar K S Dr; Balakrishna R Dr; Madhavi D Sai Dr; Manoj Sumitha Dr; Mohan Reddy Ch Ram Dr
Priority date: 2020-10-17
Filing date: 2020-10-17
Publication date: 2020-12-10
Anticipated expiration: 2028-10-17

Abstract

Our Invention "IPCM- Movable Satellite: is an intelligent propagation impairment for Movable Satellite Communication Links at the Microwave Frequencies in Location" is a method of determining communication link quality includes the steps of providing communications stations and VHF/UHF Software Communications Satellites, base stations of a terrestrial cellular network with beacon transmitters that are used to transmit two types of signals from each communications station and providing a communications device that employs the communications stations with beacon receivers and the ability to process the two types of signals to provide a user of the communications device with a real time determination of link impairments and, from this, a determination of the type and quality of service that is available to the user. The invented technology also a multiple ground station and one or more satellites for communicating between mobile subscribers and a land-based communications network, such as the global/PSTN or the Internet. The multiple ground stations geographically dispersed minimize tool charges incurred routing calls from a mobile subscriber through the land network by reducing the need for long-distance calling. The station communicates with a given satellite using the same frequency spectrum, the subscriber capacity of the system increases and/or bandwidth requirements for the communications link between ground stations and satellites may be as per user required they can have reduced. The ground-based beam forming techniques enabling each satellite to transmit signal in multiple transmission beams, each beam supporting one or more mobile subscribers. Each beam may reuse the same frequency spectrum, thereby increasing the number of subscribers supported by each satellite. Multiple ground stations cooperatively relay signals through a given satellite in a manner complementary with ground-based beam forming. A low profile mobile in-motion antenna and transmit/receive terminal system for two-way "VSAT" type satellite communication using FSS service, preferably in Ku band, supporting at the same time TV signal reception from the same satellite or a separate DBS satellite located at the same or nearby geo-stationary orbital position.The "IPCM- Movable Satellite" first type of signal is a stable continuous wave tone that provides a reference signal level and the second type of signal is a coded waveform with distinguishable correlation properties and also the invented technology a processor and display are integrated with the user's communication device and function to process these two signals and provide a user-friendly interface through which information pertaining to determined levels of link impairments and the type and quality of service available at that given location and time is communicated to the user. The user's communication device is also provided with a booster system with an alternative high-gain antenna to increase communications opportunities in difficult operating environments. 30 ANTENNA noe ELECTRONICS 806 PACViAGE ODTRIPOD -4TERMINAL FIG.8: SHOWS AN EXEMPLARY BOOSTER/HIGH-POWERED ANTENNA ASSEMBLY. 800 ANTENNA ELEMENTS STORED IN TUNE 810Ob ELECTRONICS 81081 FOLDED TRIPOD FIG. 9: IS AN EXEMPLARY EMBODIMENT OF THE BOO STER/HI GH -POWERED ANTENNA ASSEMBLY IN A DISASSEMBLED CONFIGURATION WITH ELEMENTS OF THE ANTENNA COLLAPSED AND SEPARATELY FITTED INTO STORAGE CONTAINERS.

Description

ANTENNA

ELECTRONICS 806 PACViAGE

ODTRIPOD

noe

-4TERMINAL

FIG.8: SHOWS AN EXEMPLARY BOOSTER/HIGH-POWERED ANTENNA ASSEMBLY.

800 ANTENNA ELEMENTS STORED IN TUNE 810Ob

ELECTRONICS

81081

FOLDED TRIPOD

FIG. 9: IS AN EXEMPLARY EMBODIMENT OF THE BOO STER/HI GH -POWERED ANTENNA ASSEMBLY IN A DISASSEMBLED CONFIGURATION WITH ELEMENTS OF THE ANTENNA COLLAPSED AND SEPARATELY FITTED INTO STORAGE CONTAINERS.

IPCM- Movable Satellite: Intelligent Propagation Impairments for Movable Satellite Communication Links at The Microwave Frequencies in Location

FIELD OF THE INVENTION

The invention"IPCM- Movable Satellite" is related to an Intelligent propagation Impairments for Movable Satellite Communication Links at The Microwave Frequencies in Location and also relates to a method of determining communication link quality employing beacon signals and, more particularly, a method of processing beacon signals from one or more communications stations to determine link quality between a communications device and the communications stations with the beacon signals including a continuous wave (CW) tone and a coded signal that are different for each of the communications stations.

This invention comprises a dynamic geodesic constellation of 840 autonomous satellites in low Earth orbit. Each satellite in the distributed, non-hierarchical constellation is an equally important node in the network, possesses independent switching intelligence and is capable of communicating directly with a broad variety of subscribers using portable, mobile and fixed terminals. The system will provide continuous world-wide service for voice, data and video signals. This novel satellite network has the ability to bypass traditional land-based networks and will offer a revolutionary expansion of global communications potential also the invention concerns a microwave antenna terminal applicable to two-way mobile in-motion communication systems using geostationary satellites, and capable of supporting concurrent two-way data transfer and satellite TV reception.

BACKGROUND OF THE INVENTION

Satellite beacons are widely used at microwave frequencies for three applications. The first application is to use the satellite beacon in aligning the antenna with the satellite, i.e., an antenna-tracking beacon. The second application concerns operation at higher frequencies, e.g., Ku-band, where orthogonal linear polarization is used. In this application, typically two beacon frequencies provide signals that are orthogonally polarized and thus, afford a means of polarization alignment for the user to avoid cochannel interference that degrades system communications. The third application presents a stable signal for propagation research. In this application, signal level variations received by a monitoring station can be identified with propagation losses associated with rainfall, cloud cover, and other meteorological events that degrade high frequency signals.

The ultrahigh frequency (UHF) range of the radio spectrum is the band extending from 300 MHz to 3 GHz. The wavelengths corresponding to these limit frequencies are 1 meter and 10 centimeters. The UHF frequencies have link impairments that are not present at higher microwave frequencies, and by contrast, weather conditions that degrade communications at these higher frequencies do not degrade UHF frequencies. However, while higher frequency systems are degraded by principally a single factor, UHF systems are degraded by a variety of independent factors, or link impairments, that degrade communication performance.

It would be useful to be able to assist a user of a communications device, particularly a device that exploits UHF frequencies, in determining the type of service that can be achieved at a given location and time. It would also be useful to be able to provide a real time means for individually determining the factors that impair link performance and thus, allow the user to determine the type and quality of communications service that is available and assess changes in user locations that may enhance communication opportunities.

Public telephone systems have generally used the same system architecture for over one hundred years. Conventional systems employ highly centralized and hierarchical switching facilities as nodes that tie together a complex web of connected links. While a very small portion of their subscribers use direct links to geostationary satellites, the vast majority of the links that couple the conventional phone network comprise a bewildering and dissimilar assortment of cables, wires, fibers and microwave repeaters. Like all hierarchical systems, conventional telephone networks are extremely vulnerable when the performance of any high ranking node in the hierarchy is impaired. For example, a fire in a Hinsdale, Ill. wire center denied long-distance service to the Chicago area for several days. Relatively minor software failures can disrupt or even suspend service in large, densely-populated urban areas.

This vulnerability to localized failure is compounded by the limits which a centralized architecture imposes on the expansion potential of the network. On average, every time a new subscriber is added to a conventional land-based communication network, expensive additions to switching hardware and connecting wires must be installed. The marginal cost of adding each new subscriber is extremely high, and the cost of raising that capital is a drain on telephone subscribers and on the economy at large. Conventional telephone systems are inherently circumscribed by their hierarchical design, and these limits now impose critical barriers to the enormous augmentation of capacity which the previous networks must provide to meet the burgeoning world demand for communications services in the coming decades. Several attempts to bypass these inherent limits have met with mixed results. Large consumers of phone services have begun to install their own private networks to carry large volumes of voice messages, video, and broadband data calls. While some of these expensive and awkward enhancements provide partial solutions, the unalterable constraints imposed by a centralized switching topology continue to confine the future growth of existing networks.

Some extension of the century-old centralized telephone switching infrastructure has been achieved using geostationary satellites. These spacecraft, however, offer additional communications capabilities that are quite limited. Since these satellites operate in equatorial orbits, they are not accessible to customers located in high latitudes. Because they must share their orbit with many other services, their number is restricted to a relatively small population. Since all of these spacecraft occupy a single circular orbit, they cannot be connected together in a geodesic network. A geodesic network, which could provide enormously greater capacity, must be generally spherical in shape. Geostationary satellites also suffer from a very serious disadvantage--the distant altitude of their orbits.

These satellites are so far from Earth that the signal takes about one-quarter of a second to traverse the nearly 50,000 miles (80,000 km) along the round trip from the ground up to the satellite, and back to the ground. The delays sensed by the telephone user's ear that are introduced by this long round trip are not only annoying, but can render some conversations which are relayed between more than one geostationary satellite virtually unintelligible. Radio signals which are exchanged between a ground station and a geosynchronous satellite may also be impaired by this great round trip distance. A telephone customer on the ground using a portable phone who wanted to communicate directly with a satellite in geostationary orbit would need a telephone capable of producing an output in excess of hundreds of Watts. Generating this power output is not only thoroughly impractical for users of portable phones, but may also create a radiation hazard for the individual wielding the telephone.

Geostationary satellites do not supply an adequate solution to the formidable expansion needs of conventional telephone networks. Although cellular service has grown rapidly over the past decade, even greatly expanded cellular service would not provide an adequate solution. Cellular systems are plagued by poor performance, and are ultimately constrained by the same structural limits that circumscribe the future of land-based systems. Cellular customers are still limited to geographic regions served by radio towers called "cell sites." Even in the United States, these cell sites are not universally prevalent, since market forces restrict cellular service to only the most densely populated urban portions of our country. Cellular service is available to only a small minority of privileged users in wealthy countries, and is virtually non-existent in lesser developed parts of the world.

The publications noted below disclose various systems that pertain to communication systems that are designed to operate on the Earth's surface or in conjunction with satellites flying in low Earth orbits. Bertiger, Leopold and Peterson describe a "Satellite Cellular Telephone and Data Communication System" in European Patent Application No. 891184 58.2. This application sets out some of the details of Motorola's proposed Iridium" communication system. The Iridium" system is currently designed to utilize sixty-six (66) satellites in low Earth orbit which would generate relatively large footprints of radio beams due to their extremely low mask angle of eight and one half degrees (81/2°). Because of these very large footprints, the communications capacity that may be offered by the Motorola network would be substantially constrained. In addition, this system would employ "satellite-fixed cells" which are not defined by any constant boundaries on the Earth. These cells would sweep over vast regions of the Earth at very high speeds as the Iridium" satellites fly overhead. This method of using satellite-fixed cells introduces extremely complicated "hand-off" problems when one satellite moves out of range of supplying service with a subscriber. At that time, another satellite must assume the responsibility of supporting the subscriber's call without interruption.

In U.S. Pat. No. 5,107,925, Bertiger et al. disclose a multiple beam space antenna system for facilitating communications between a satellite switch and a plurality of Earth-based stations. No system that is currently available to the general public is capable of taking advantage of the enormous enrichment of communications capacity that could be achieved if the traditional centralized grid of terrestrial switches, and their connecting cables, wires, fibers and microwave repeaters could be completely bypassed. Public phone companies are not presently able to sell continuous global service to customers who wish to use phones that are not coupled to the land-based network. The problem of providing an economically feasible network for voice, data and video which can be used by subscribers all over the world has presented a major challenge to the communications business. The development of a communications system that offers a solution to the immutable obstacles to growth which bind conventional phone networks would constitute a major technological advance and would satisfy a long felt need within the telephone industry.

The invention relates to radio communication systems with increased capacity. The system can include a number of roving, automobile-mounted or handheld telephone sets served by either fixed, ground-based stations or by orbiting satellites or by a combination of both. The capacity of such systems to serve a large number of subscribers depends on how much of the radio spectrum is allocated for the service and how efficiently it is used. Efficiency of spectral utilization is measured in units of simultaneous conversations (erlangs) per megahertz per square kilometer. In general, spectral efficiency can be improved more by finding ways to re use the available bandwidth many times over than by attempting to pack more conversations into the same bandwidth, since narrowing the bandwidth generally results in the need to increase spatial separation between conversations thus negating the gain in capacity. Therefore, it is generally better to increase the bandwidth used for each conversation so that closer frequency re-use is possible.

Spread-spectrum communications systems (e.g., CDMA systems) that increase the signal bandwidths using heavy redundant coding, such that a signal can be read even through interference from other users, offer high spectral efficiency. Using such systems, several users in the same cell can coexist in the same bandwidth, overlapping in both frequency and time. If co-frequency interferers in the same cell can be tolerated, co-frequency interferers one or more cells away can also be tolerated since distance will lessen their interference contribution, so it would be possible to re-use all frequencies in all cells. Spread-spectrum system capacity is said to be self-interference limited because each unwanted signal that is received simultaneously with the desired signal, and on the same frequency, contributes an interference component. Some systems, however, such as satellite communications systems, are already limited by natural noise, so the wideband spread-spectrum approach is then not necessarily the best technique for maximizing capacity. Consequently, it would be desirable to re-use the whole spectrum in every adjacent cell or region without incurring the self-interference penalty of wideband spread-spectrum.

Figure 1: shows a typical arrangement of a cellular telephone network using land-based stations. This figure is illustrative of such networks only, for example, cells are not always of such regular size and shape and as a general definition a cell may be described as an area illuminated with a distinct signal. Cells can be illuminated from their geographical centers, but it is more common to illuminate a cluster of three cells from a common site at the junction of the three cells, as site real estate cost is a major economic consideration. The antenna radiation patterns for central illumination of a cell would generally be omnidirectional in azimuth. It is also common to narrow the radiation pattern in the vertical plane so as to concentrate the energy towards land-based telephones and avoid wasting energy skywards. When the transmitters and antennas for three cells are collected onto the same site for economy, the antenna patterns are then only required to illuminate 120 degree sectors, and the resultant azimuthal directive gain largely compensates for the double distance to the far side of the cell. The antenna pattern can be shaped appropriately so as to provide a gain commensurate with the maximum range needed in each direction, which is halved at +/- 60 to 62 degrees compared to mid-sector. Thus a sectorized antenna pattern can be narrowed to -12dB at +/- 60 to 62degrees, giving a mid-sector gain of about 8 to 9dB to assist in achieving the maximum range in that direction.

Using central illumination, the U.S AMPS cellular mobile telephone system denies re-use of the same frequency within a 21-cell area around a given cell. This is called a 21-cell frequency re use pattern and results in co-channel interference being approximately 18dB below a wanted signal when all channels are concurrently in use (commonly called maximum load). Such a 21 cell re-use pattern is illustrated in Figure 2. Certain re-use pattern sizes such as 3, 4, 7 and products thereof (e.g., 9, 12, 21.) result in co-channel interferers being equidistant from the wanted signal and located on the vertices of a hexagon, separated by a number of cells equal to the square root of the pattern size.

In practice, illumination takes place from sites at the junction of three cells. Although the re-use pattern is a 21-cell pattern, it can also be described as 7-sites each having a 3-frequency re-use pattern around the three, 120 degree sectors. The signal to co-channel interference characteristics arising from this form of illumination are not exactly equivalent to those characteristics which result from central illumination (due to the antenna directivity it can be shown that interference with respect to a particular signal arises principally from two other sites whose antennas are firing in the right direction, and not from six equidistant cells which transmit on a common frequency as would be the case in central illumination). The 3-sector, 7 site method of illumination is sometimes called vectorization, which can give the erroneous impression that an originally larger cell was split into three smaller cells or sectors by use of directional antennas. This impression, however, is inaccurate because the arrangement used for illuminating three cells from the same site is merely an economic arrangement that actually has slight disadvantages over central illumination with respect to technical performance but is otherwise very similar.

Cell-splitting is another concept entirely, being a way of obtaining more capacity per square kilometer by providing base stations more densely on the ground. Introducing cell splitting in an already existing system usually requires complete revamping of the frequency re-use plan, as it is conventionally not possible simply to split a cell, for example, into three cells and to re use the original frequencies three times over. This would result in the three new cells operating on the same frequency with no spatial separation, which would present a problem for a mobile phone on the boundary between two cells where it receives equal strength (but different content) signals on the same frequency from both. Thus, it would be desirable to allow a cell to be split into sectors with the same frequencies being used in each without the above-described interference problem.

Similar capacity issues arise in designing a satellite communications system to serve mobile or handheld phones. On handheld phones, omnidirectional antennas of indifferent performance are all that in practice the majority of consumers are willing to accept. Directional antennas that have to be oriented toward the satellite or larger, more cumbersome antennas do not now find favor in the marketplace, so it is necessary for the satellite to provide a high enough signal strength at the ground to communicate with such devices. The signal strength received at the ground from a satellite is usually measured in units of watts per square meter or dBW per square meter on a logarithmic scale. For example, a flux density of the order on -123dBW per square meter is used for voice communication to provide an adequate link margin for multipath fading, shadowing, polarization mismatch etc., using a downlink frequency of 2GHz. The total number of watts radiated by the satellite is then equal to this required flux density times the area of the geographical region it illuminates. For example, to provide such a voice channel anywhere in the entire United States, having an area of 9 million square kilometers requires a total radiated power of:10 - 12.3 x 9 x 10 12 = 4.5 watts from the satellite.

9x10' 1012.3 x = 4.5 watts from the satellite.

One voice channel would not, of course, provide a useful capacity. Five to ten thousand Erlangs is a more reasonable target for serving the United States. One way of increasing the capacity would be to generate 4.5 watts on other frequencies too, each of which could carry one voice channel; but a 45k watt satellite would be very large and expensive to launch and would not be an economic way to provide 10000 erlangs capacity. It is therefore more efficient, having used 4.5 watts of satellite RF power to create one voice channel's worth of flux density at all places in the United States, to find ways which will allow the voice carried by that flux to be different at different places, thus supporting many different conversations using no more power or bandwidth.

The ability of a satellite to modulate the same radiated flux density differently in different directions depends on the angular discrimination provided by its antenna aperture. The angular discrimination of an antenna (in radians) is on the order of the ratio of the wavelength to the diameter of the antenna. Using an exemplary downlink frequency of 2GHz (15cm wavelength) an antenna of 1.5 meters in diameter theoretically has an angular discrimination on the order of 1/10th of a radian or 5.7 degrees, which, from an orbital height of, for example, 10000 kilometers, allows discrimination between 37 different directions within the United States coverage area. Thus, the same 4.5 watts of satellite radiated power could then support not just one, but 37 different conversations. One way of creating 37 different beams is shown in Figure 3. A parabolic reflector focuses the radio energy from a pattern of 37 different feeds down to the earth. An image of the feeds is projected onto the ground forming the desired separately illuminated areas. Unfortunately, using this technique there is spillover from one area to another, and in any case a mobile phone on the boundary between two or three cells receives equal signals from two or three feeds. If these signals are independently modulated, the phone receives a jumble of three conversations which it cannot decipher. Accordingly, conventional systems have been unable to exploit the potential capacity increases which would be realized using discrimination.

Knowingly between a plurality of mobile subscribers and center ground station, utilize a plurality of wave beams that transmit and receive between satellite and the portable terminal to communicate by the track repeater satellite, and simultaneously the processing operation setting that is used to control these a plurality of wave beams that calls adaptive beam former at described central station rather than be arranged on satellite. The result who puts into practice this technology is that the complexity of orbiter significantly reduces. Described technology depends on many signal communications of realizing by this way between center ground station and the satellite, keeps their relative phase and amplitude that is, that is the coherence. A kind of coherent transfer scheme is with Nyquist speed or higher speed in these a plurality of signals each to be sampled, and forms the high-speed time-division multiplex of sampled signal then. In time division multiplexing stream, comprise known signal synchronously for the ease of time on the satellite and frequency.

Reverse link from the satellite to the central station preferably also to the signal that on satellite, receives by the different elements of multiple element antenna adopt high-speed time division multiplex, to keep relative coherence, so just allow the ground wave beam to form and not only be used for receiving but also being used for emission. The coherence keeps with time division multiplexing so relatively, promptly, utilize first time division multiplexer that the real part (homophile or I) of sampled complex waveform is realized time division multiplexing, and utilize and corresponding imaginary part (quadrature or Q) the realization time division multiplexing of synchronous second time division multiplexer of first time division multiplexer to the sampled complex waveform, this technology will be called as OTDM.

People such as Mayfield are being entitled as " utilizing the ground wave beam of S-CDMA to form "U.S. Patent No. 5,903, taught in 549 and utilized CDMA to present link transmission is kept required coherence between the antenna array element signal technology, described patent is attached, and this is for referential use.

Formerly have in the technological system, single central station (ground station) passes through one or more satellite forward signals, thereby provides service to many portable terminals. But utilizing a ground station is not optimum in some communication system. Because one or more satellites can provide covering for quite vast geographic area, and single ground station geographically may be away from the final destination of mobile phone users calling. Like this, the route of described calling from described ground station to the final destination born the expense of long distance possibly. Finish given mobile phone users calling the highest needed toll charge at a distance of arranging that far enough a plurality of ground stations just can reduce to greatest extent each other. Another shortcoming is to be produced by frequency reuse restriction intrinsic in the single earth station system. A plurality of ground stations enough far away of being separated by on the geography can reuse same frequency spectrum and come and one or more satellite communications. This is possible, because as long as spatially have suitable difference between the primary signal source, these satellites can be distinguished a plurality of signals in the same frequency spectrum easily.

But, still need a kind of like this communication system, it has suitably arranged a plurality of ground stations in given geographic area, and each adopts the ground station of beam-forming technology can cooperate by one or more support satellites the system of signal forwarding to a plurality of mobile subscribers. A low profile mobile in-motion antenna and transmit/receive terminal system for two-way data type communication using data service at frequencies in a first frequency band, supporting at the same time concurrent TV signal reception of signals broadcast in a second frequency band, such communication being with the same satellite or with two or more satellites located at the same or close geo-stationary orbital position. For purposes of the present invention, satellites at substantially the same orbital location would be within the beam width of the mobile in-motion antenna, typically within a range of 0 to 0.3 degrees of orbital location.

In particular, the present invention enables and facilitates the applications of broadband data communications and satellite TV reception at a wide variety of moving vehicles such as recreational vehicles (RVs), sport utility vehicles (SUVs), buses, trucks, trains, automobiles, boats, and even aircraft. For example, one application would enable passengers in a vehicle to make a wireless "always on" broadband connection to the Internet from a personal computer inside the vehicle at the same time that other passengers are watching satellite TV broadcasts from, for example, the DirecTV network. This could be done in a consumer vehicle and also in commercial vehicles such as buses and trains. In that case, passengers could open their laptop computers and perform customary Internet functions such as e-mail and Web browsing. Other passengers could be watching satellite TV.

In another example application, the two-way satellite connection and the Global Positioning System (GPS) information included with the invention system, which provides the location of the vehicle, could be interfaced with the vehicle's telematics system to provide up-to-date downloads of information for navigation, location of local hotels, restaurants, and local points of interest. The active two-way communication link could also be used to obtain real time emergency assistance where the vehicle's location would be communicated to the emergency assistance organization. For commercial vehicles such as trains, buses and aircraft, the Internet connectivity enabled by the invention allows provision of wireless "hot spots" covering the inside of the moving vehicle. The satellite TV portion of the system could also be used to distribute programming to individual seats, if desired. For commercial trucks, the invention combines vehicle location information and "always on" connectivity that may be used for dispatch and routing by a central authority.

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A application is related to the following commonly-owned and commonly-assigned pending patent applications: Terrestrial Antennas for Satellite Communication System by Asu Ram Jha, filed on Dec. 2, 1993 and assigned U.S. Ser. No. 07/984,609, and claiming the benefit of priority of a parent application entitled Terrestrial Antennas for Satellite Communication System by

Asu Ram Jha, filed on Nov. 8, 1991, and assigned U.S. Ser. No. 07/790,273;Switching Methods for Satellite Communication System by David Palmer Patterson & Moshe Lerner Laron, filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,805; Beam Compensation Methods for Satellite Communication System by David Palmer Patterson and Mark Alan Sturza, filed on Jul. 8, 1993 and assigned U.S. Serial No. 08/088,714, and claiming the benefit of priority of a parent application entitled Earth Fixed Cells Beam Compensation for Satellite Communication System by David P. Patterson and Mark Alan Sturza, filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,318 now U.S. Pat. No. 5,408,237;

Spacecraft Antennas & Beam Steering Methods for Satellite Communication System by Douglas Gene Lockie, filed on Oct. 28, 1992 and assigned U.S. Ser. No. 07/967,988 and claiming the benefit of priority of a parent application entitled Spacecraft Antennas & Beam Steering Methods for Satellite Communication System by Douglas Gene Lockie, filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,271;Spacecraft Designs for Satellite Communication System by James R. Stuart and David P. Patterson, filed on Aug. 18, 1992 and assigned U.S. Ser. No. 07/931,625 and claiming the benefit of priority of a parent application entitled Spacecraft Designs for Satellite Communication System by James R. Stuart filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,748;

Spacecraft Antisatellite Link for Satellite Communication System by Douglas G. Lockie et al., filed on Jul. 16, 1992 and assigned U.S. Ser. No. 07/915,172;Method of Conducting a Telecommunications Business Implemented on a Computer by Edward F. Tuck, filed on Jun. 8, 1992 and assigned U.S. Ser. No. 07/895,295;Traffic Routing for Satellite Communication System by Moshe Lerner Liron, filed on Feb. 9, 1993 and assigned U.S. Ser. No. 08/016,204; and Modular Communication Satellite by James R. Stuart, filed on Jun. 11, 1993 and assigned U.S. Ser. No. 08/075,425.

OBJECTIVES OF THE INVENTION

1) The objective of the invention is to a determination of the type and quality of service that is available to the user. The first type of signal is a stable continuous wave tone that provides a reference signal level and the second type of signal is a coded waveform with distinguishable correlation properties. 2) The other objective of the invention is to the invented technology a processor and display are integrated with the user's communication device and function to process these two signals and provide a user-friendly interface through which information pertaining to determined levels of link impairments and the type and quality of service available at that given location and time is communicated to the user. 3) The other objective of the invention is to the user's communication device is also provided with a booster system with an alternative high-gain antenna to increase communications opportunities in difficult operating environments and also the invention is to a wherein the communication device comprises a transponder. The invention to a wherein the communication device comprises at least one of a mobile voice communicator and a mobile data communicator. 4) The other objective of the invention is to a wherein the means for receiving and processing the beacon signals comprises a processor. The invention to a wherein the means for receiving and processing the beacon signals comprises one or more beacon receivers.

) The other objective of the invention is to a wherein the one or more beacon receivers comprise a continuous wave (CW) tone beacon receiver. The invention to a wherein the one or more beacon receivers comprise a coded signal beacon receiver and also the invention is to a wherein the means for communicating information provides a real time indication of link quality.

SUMMARY OF THE INVENTION

A method of determining communication link quality according to the present invention generally involves: providing a plurality of communications stations (e.g., UHF communications satellites, base stations of a terrestrial cellular network) with beacon transmitters that are used to transmit two types of signals from each communications station; and providing a communications device that communicates with the communications stations, the communications device having beacon receivers and the ability to process the two types of signals to provide a user of the communications device with a real time determination of link impairments and, from this, a determination of the type and quality of service that is available to the user.

The first type of signal is a stable continuous wave (CW) tone that provides a reference signal level, and the second type of signal is a coded waveform. In an exemplary preferred embodiment of the present invention, a processor and display are integrated with the user's communication device and function to process these two signals and provide a user-friendly interface through which information pertaining to determined levels of link impairments and the type and quality of service available at that given location and time is communicated to the user.

The communications device is provided with means to determine link loss, scintillation effects, Doppler offsets, noise levels and interference, as well as means to control the transmitter signal level of the communications device. With this added functionality, the user is provided with means to understand the limitations of the existing communication capabilities and the user's transmission level is controlled to reduce the dynamic range of user signals received and processed by the satellite thereby increasing system effectiveness. The invention, a method of determining communication link quality employing beacon signals includes the steps of: equipping a plurality of communications satellites with beacon transmitters that generate beacon signals including a continuous wave (CW) tone and a coded signal that are different for each of the communications satellites; and providing a communications device, that is capable of establishing UHF communications links with the communications satellites, with a mechanism for receiving and processing the beacon signals to determine the quality of the UHF communications links. According to a preferred method, for each of the communications satellites: the coded signal is within a communications bandwidth employed by the communications satellite; and the CW tone is out of the communications bandwidth. By way of example, the communication device is a transponder or mobile telephone. The mechanism for receiving and processing the beacon signals includes one or more beacon receivers, such as a continuous wave (CW) tone beacon receiver and a coded signal beacon receiver.

An exemplary preferred method of determining communication link quality employing beacon signals according to the present invention further includes the step of providing the communications device with a mechanism for communicating to a user information pertaining to the quality of the UHF communications links, for example, noise information, interference information and/or scintillation information. In a preferred embodiment, the mechanism for communicating information provides a real time indication of link quality. In a preferred embodiment, the mechanism for communicating information includes a display device operably interconnected to the communications device. An exemplary preferred method of determining communication link quality employing beacon signals according to the present invention further includes the step of providing the communications device with a mechanism for adjusting a transmission power of the communications device. In a preferred embodiment, the mechanism for adjusting transmission power includes a booster device with an alternative high gain antenna, e.g., a log periodic antenna or a Yagi antenna. In a preferred embodiment, the alternative high gain antenna is articulated so that it can be manipulated as desired into an opened operating configuration or a collapsed storage configuration.

The invention, a method of determining communication link quality employing beacon signals includes the step of: employing one or more beacon receivers and a processor to receive and process beacon signals from one or more communications stations to determine link quality between the communications device and the communications stations, the beacon signals including a continuous wave (CW) tone and a coded signal that are different for each of the communications stations. In a preferred embodiment, the processor is programmed to process data pertaining to measured signal levels of the beacon signals to determine one or more link impairment factors, for example, a propagation loss factor, an interference factor and/or a noise factor. In a preferred embodiment, the processor is programmed to process data pertaining to variations in measured signal levels of the beacon signals to determine one or more link impairment factors, for example, a scintillation factor. In a preferred embodiment, the processor is programmed to sequentially determine the link qualities. The communications stations are, for example, UHF communications satellites or part of one or more terrestrial cellular networks.

The invention, a method of determining communication link quality employing beacon signals includes the step of: providing a machine-readable program to a processor that, when executed, enables the processor to control a communications device to process beacon signals from one or more communications stations, the beacon signals including a continuous wave (CW) tone and a coded signal that are different for each of the communications stations, to determine link quality between the communications device and the communications stations and to facilitate user selection of an available communications station that is most advantageous for communications

The Satellite Communication System disclosed and claimed in this patent application overcomes the limits that circumscribe the performance and potential of existing telephone systems. The present invention is capable of offering continuous voice, data and video service to customers across the globe on the land, on the sea, or in the air. Instead of merely improving upon or expanding existing land-based systems, the present invention bypasses centralized terrestrial switching hardware by placing all the intelligence of the network in orbit. Unlike conventional hierarchical systems, which are linked together by a complex web of wires, cables, glass fibers, and microwave repeaters that are very expensive to build and maintain, the present invention liberates the true communications potential of existing land-based networks by routing signals through spacecraft in low Earth orbit.

The essence of the system disclosed in this application is a dynamic constellation of satellites. Each satellite functions as a communications node of equal rank and importance that is linked to its nearest neighbors. The topology of the constellation resembles a geodesic dome, which offers several advantages over the topology of conventional networks. In previous systems, some call traffic is diverted through distant nodes when the most direct routes between the origin and destination of a call are completely saturated with traffic. These lengthy diversions greatly impair the quality of the connection by introducing time delays, echoes, and additional noise. In the geodesic network of the present invention, such a low-quality diversion becomes unnecessary, since a parallel route can be found which only increases delays by a relatively small amount.

The novel constellation of satellites not only offers a graceful response to overloads by minimizing deleterious diversions of traffic, but also eliminates the devastating consequences of the failure of a node. In current systems, when a node fails, service for entire sections of the network is disrupted. In dramatic contrast, the failure of a node in a geodesic system can be compensated by simply removing the inoperative satellite from the network. Adjacent spacecraft in the web then share the workload of their disabled neighbor until it can be repaired or replaced.

The preferred embodiment of the invention comprises a low Earth orbit satellite system that includes 40 spacecraft traveling in each of 21 orbital planes at an altitude of 700 km (435 miles). This relatively large number of satellites in the constellation was selected to provide continuous coverage of the Earth's surface at a high minimum mask angle of forty degrees with respect to the Earth's surface, thus avoiding foliage, terrain, and minimizing the length of the signal's passage through rain. Each of the individual 840 spacecraft functions as a sovereign switch which knows the position of its neighbors, and independently handles traffic without ground control. The satellites are capable of transporting calls to millions of customers using portable, mobile and fixed residential and business terminals, and gateways to public phone networks. The constellation uses the 20 and 30 GHz frequency bands for communications between Earth and the constellation, and the 60 GHz band for communicating among the satellites. The use of these extremely high frequencies allows for the use of relatively low power, miniaturized antenna components both on the ground and aboard the satellites. The entire constellation is designed to serve over twenty million subscribers and 60,000 full time DS-0 (64 kbps) circuits. The satellites will be coupled to traditional public and private phone systems on the ground through gateways which each utilize relatively large antennas and handle large volumes of call traffic. In the preferred embodiment of the invention, this interface between the terrestrial systems gateway and the terrestrial network is based on current standard ISDN interfaces to preserve compatibility.

Unlike presently available cellular systems which relay calls to subscribers from local radio towers, the present invention offers direct communication between the satellites of the constellation and individuals using lightweight portable, mobile and fixed telephones. This direct link is made possible by innovative miniature antennas coupled to handheld phones. The antennas can be integrally formed as part of the housing of portable phones or may be used as separate components mounted on the outside of a vehicle. They are designed to communicate with satellites that are more than forty degrees above the user's horizon so that interference and shadowing caused by terrain and nearby buildings is substantially eliminated. The handheld antennas comprise multi-element, electronically steerable phased arrays that measure only a few inches in diameter and are less than two inches (5.1 cm) high. While the signals from these antennas are sufficiently powerful to provide dependable service virtually anywhere on land, sea or in the air, the radiated power is low enough to insure that the telephone does not pose significant radiation hazards.

The invention includes a faceted, high-gain, antenna array on each satellite. This electronically steered array is formed from a number of flat antenna panels which are fabricated from ultra lightweight honeycomb materials and advanced composites. The interior of the dome-shaped antenna array contains electronic equipment and batteries, and is used to store solar cell panels which unfurl when the spacecraft reaches its final orbit. Each panel contains a large number of gallium-arsenide (GaAs) monolithic microwave integrated circuits (MMIC) which comprise its antenna array elements, power amplifiers and low-noise receiver pre-amplifiers. The cup-like shape of the satellite allows several satellites to be nested in a compact arrangement that fits within the payload bay of a launch vehicle.

Each antenna array simultaneously generates 256 beams which are electronically steered to 4,096 positions on the surface of the Earth. Each individual beam illuminates a region on the ground called a "cell" that measures roughly 400 (20x20) square kilometers. Since the cells are small and the satellite moves rapidly over the Earth's surface, a system in which the cells were fixed relative to the satellite would cause a terminal to be "handed-off" from cell to cell every few seconds. To avoid this, an innovative logical/physical cell mapping scheme is utilized to create "Earth-fixed cells" which enhances the efficiency of the system and eliminates click noise during telephone calls that might result from a constant series of handoffs between satellites.

The invention also incorporates novel software which runs on a processor onboard each satellite in the network. Autonomous Orbit Determination (AOD) algorithms provide each spacecraft with location information about its own position and the position of every other satellite in the network. This position information is used to determine the optimum pathway for routing call traffic among the satellites in the constellation. These data are also used to maintain each spacecraft in its proper orbital position, to steer antennas that receive and transmit signals from neighboring satellites, and may be used to offer Radio Determination Satellite Service (RDSS) which is superior to service currently available from the Global Positioning Systems (GPS) service. One embodiment of the AOD software employs a ranging algorithm that calculates distances between spacecraft or between spacecraft and ground stations by measuring time delays that are inherent in the radio transmissions conveyed by the network.

A second embodiment of the AOD software incorporates an algorithm which fixes spacecraft position by measuring the Doppler shifts of satellite or ground station transmissions. The AOD software also determines the attitude of the spacecraft using data from the antenna steering function. A third embodiment uses signals from known, fixed location ground terminals to determine both satellite location and attitude with great accuracy. Appendix A, which accompanies this specification, contains a complete computer program that embodies the AOD software. The AOD software generates position information that is used by a second computer program that utilizes a novel Adaptive Routing Algorithm (ARA). Like the AOD software, the ARA runs continuously on a processor on board each satellite. The output produced by the AOD program enables the ARA software to monitor the constantly-changing topology of the constellation. The ARA is also responsible for keeping track of the flow of call traffic through the nodes and links of the constellation and to compensate for traffic congestion and node failures. Appendix B, which accompanies this specification, contains a complete computer program that embodies the ARA software.

Each satellite carries fast packet switch circuitry to direct calls among other satellites and to customers on Earth using portable, mobile and fixed terminals. The voice, data and video information within the communication signals or telephone calls is arranged in a digital format called a "packet." A single call may include thousands, millions, or even billions of packets. The packets comprise a sequence of several hundred ones and zeroes, and are divided into two general groups or strings of bits: the first called a "header," the second referred to as a 'payload." The header includes the address of the destination of the packet, while the payload contains the digitized substance of the call itself. The present invention utilizes a "datagram" approach that routes every packet conveyed by the system independently at every node in the network. The packets are directed along an optimized pathway through the network by a fast packet switch that directs traffic based on instructions from the processor that continuously runs the Adaptive Routing Algorithm.

The innovative switching methods employed by the fast packet switch present on each satellite optimize the utilization of the network facilities and minimize transmission delays. These and other drawbacks and difficulties found in conventional radio communication systems, satellite communication systems and hybrids thereof are overcome according to the present invention. According to exemplary embodiments of the present invention, matrix processing can be used to form numerical combinations of data sample streams. The matrix coefficients are selected, and can be periodically adjusted, so that each of a plurality of receivers receives its intended signal with substantially zero interference. According to another exemplary embodiment of the present invention, signal processing does not adapt to the movement of mobile phones or to new call set-up and termination, but operates in a deterministic way and instead the traffic is adapted to the deterministic characteristics of the signal processing using a dynamic traffic channel assignment algorithm.

The present invention makes this communication system become possible method and apparatus to satisfy this and other demands by providing. According to communication satellite system of the present invention adopt one or more satellites the many portable terminals that are distributed in one or more service areas and be connected to PSTN or the fewer purpose ground station of internet between forwarding information. Adopt beam-forming technology to make each satellite all launch a plurality of transmission beams, thereby increase the number of users that each satellite is supported. The invention not only provided method but also generator, described method and apparatus to make a plurality of ground stations carry out relaying by each satellite cooperation to signal in the mode that the ground beam technique that is adopted is replenished. In the first embodiment of the present invention, there is control in different ground stations to the whole bandwidth in the transmission beam subclass. In a second embodiment, different ground stations is possessed of control power to the different piece of described bandwidth, but is allowed to use in any transmission direction described part bandwidth. In the 3rd embodiment, all ground stations all are possessed of control power to the whole bandwidth in any transmission direction, but when work on overlapping wave beam or adjacent direction, do not use same bandwidth, thereby avoid interference.

Digital beam forms provide an approach by this way a plurality of signals that output to multielement array to be carried out combination and processing, and the result is the one or more directional beams of output in the described antenna array. As long as change the linear combination of a plurality of signals of input beam-forming device simply, i.e. the direction of each wave beam of may command and signal content two aspects. Be input to digital beam form device signal each all comprise complex value stream, and Beam-former is by finishing a series of matrix operations the combination in addition of these input signal streams, and each antenna element is all launched the signal of the potential different vectorial combination of representing input signal as a result. By adjusting one group of coefficient that is applied on the input signal, digital beam forms device can dynamically change any one of antenna array output or the direction and the content of all wave beam. Because the directivity of beam former output, each wave beam can be reused identical frequency spectrum. So digital beam formation technology allows to increase significantly the number of users of mobile terminal that given service area is supported by given satellite.

In the ground beam-forming technology, digital beam forms device and resides in the ground station, handles its a plurality of input signals, and will export the one group of vector that produces required wave beam when being input to suitable multielement array. Described output vector group is transmitted into satellite, and the system on the satellite is fed to this antenna array to this group vector, thereby produces one group of required transmission beam, to cover given service area. Ground digital beam formation technology has been simplified the design of satellite, but has introduced complexity during by same satellite forward signal when each more than one ground station that all adopts the ground beam-forming technology. As mentioned above, system of the present invention is provided for the method and apparatus that a plurality of wave beams form ground station, so that in an advantageous manner by same satellite forwarding information.

According to communication satellite system of the present invention in being distributed in a service area many mobile subscribers and fewer purpose be connected to PSTN or internet ground station between forwarding information. Ground station receives the signal that will be forwarded to the mobile subscriber via satellite from PSTN or internet. Ground station encodes to these signals and modulates, and utilizes Beam-former that signal is formed the antenna array element drive signal. Carry out multiplexed to the antenna array element drive signal then and it be transformed to presenting the link uplink frequency, so that be transmitted into satellite. Above ground station with identical present link frequency bands to satellites transmits; make satellite receive the summation of overlapping ground station's signal. Described satellite is synchronized to concurrent lost accent (misalignment) information of the Known signal patterns that is included in ground station's signal so that make ground station can calibrate their timing and frequency reference.

The satellite utilization is presented the link reception antenna from ground station's received signal, and will present link signal and be divided into antenna array drive signal and synchronizing signal. Synchronizing signal produces above-mentioned error information through handling. The antenna array drive signal be modulated into satellite to move (that is, communication downlink) wave band (for example, the S-wave band), and amplify with S-wave band power amplifier array, to drive polyandry emission array, so that produce the multiple transmission beam that points to the mobile subscriber in the different honeycombs of service area. Different ground stations is based upon the wave beam that separates on space scale, dimensions in frequency or the time scale, in order to avoid the phase mutual interference.

According to the present invention, all ground stations can present the link frequency spectrum to satellites transmits with identical; thereby satellite receives the linear superposition combination from the signal of all ground stations. But the characteristic of each signal all is through selecting, and in each ground station's generation, make signal transformation from the Different Ground station become different S-wave band wave beam, different S-audio range frequency or different tman slots (or any combination of this three species diversity), thereby avoid being derived from the Different Ground station and being on S-wave band down link, to disturb between the signal of destination with different mobile subscribers. Otherwise, on satellite, utilize multielement array from mobile subscriber's received signal, amplify and filtering after, carry out multiplexed and frequency translation one-tenth is presented down link frequencies to the signal that is received, and be forwarded to ground station. Ground station receives and the multielement array signal that satellite is transmitted is carried out multichannel decompose, and signal is carried out digitalization so that carry out digital processing. Digital processing comprises digital channelizing, so that these signals are divided into several frequency channels by means of digital filtering or Fourier transform, and carry out digital wave beam and form, to strengthen the signal that the specific direction by the user of given ground station service of satellite from the honeycomb that is equivalent to be in service area receives. Ground station deciphers the subscriber signal of distributing to their processing then, and signal is coupled to PSTN or internet.

BRIEF DESCRIPTION OF THE DIAGRAM

FIG. 1: is a diagram illustrating an exemplary implementation of the method of the present invention for a communications device and a plurality of communications satellites. FIG. 2: is a diagram illustrating an exemplary implementation of the method of the present invention for a communications device and a terrestrial cellular network. FIG. 3: is a functional block diagram of an exemplary space segment. FIG. 4: is an exemplary display suitable for employment with a communications device. FIG. 5: is a diagram of spectra received by a communications device. FIG. 6: is a functional block diagram of a communications device modified according to an exemplary preferred embodiment of the present invention; FIG. 7: is a flowchart illustrating a method of determining communication link quality employing beacon signals. FIG. 8: shows an exemplary booster/high-powered antenna assembly. FIG. 9: is an exemplary embodiment of the booster/high-powered antenna assembly in a disassembled configuration with elements of the antenna collapsed and separately fitted into storage containers. FIG.10: is an illustration of a communications system with which the present invention is employed.

FIG.11: is a block diagram of the mobile antenna terminal in accordance with the embodiment of the invention. FIG.12: is a flow chart of an exemplary process performed in the implementation of the present invention. DESCRIPTION OF THE INVENTION

FIG. 1: is an exemplary UHF satellite communication system 100 and the limitations commonly found in such systems, which are addressed by the present invention. Communications satellites 102 a, 102 b are configured in constellations that typically provide users with two alternative satellites within the user's field of view. According to the present invention, beacons signals are broadcast from each satellite having two spectral components that are unique to each satellite. The one component is a CW signal offset from the frequencies used to communicate and having a frequency, fi, which differs from the CW frequency used by other satellites. The second spectral component, Ci, is a coded waveform transmitted within the frequency band allocated for the satellites and, preferably, at a lower level than the communication signals to avoid interfering with them, and again each coded waveform is unique to a particular satellite. Thus, the beacon signals for a given satellite can be distinguished from those used by other satellites and selected in a manner that beacon signals from other satellites do not interfere with beacon signals from other satellites. An exemplary preferred embodiment of the coded waveform is a pseudo-random code such as a simple shift register sequence that has well behaved autocorrelation properties.

FIG. 1: also illustrates typical UHF limitations. The earth's ionosphere is one such limitation and two distinct types of degradation can result. Because of dynamic variations of the ionospheric properties, the signal level can vary with time, a phenomena referred to as scintillation. A second degradation results from Faraday rotation that alters the polarization of signals transferring the ionosphere. Thus, the polarization of the satellite signal differs from the polarization intended by design, and this difference results in some degradation in signal reception. The signal path can be blocked by either man-made or natural terrain features and loss of signal power occurs degrading communications. Likewise, signals can be reflected from man-made or natural features resulting in multipath signal components that are delayed in time relative to the direct signal and interfere with the direct signal reception degrading communications. The UHF frequency range has numerous users in addition to those intended for this particular satellite communication system and these interfering signals can also degrade the operation of the satellite communication system.

The noise level at the user's receiver is comprised of two components, the natural Galactic noise and man-made noise components. Man-made noise depends on the environment surrounding the users and with modem day urbanization, man-made noise levels commonly exceed the natural noise sources. Foliage surrounding the user also reduces UHF signals and thus, foliage attenuation degrades performance. Finally, the presence of the user and the environment surrounding the user affects the performance of the user's antenna further degrading communication performance. In such a system design according to the present invention, the user is provided with a choice of satellites for communication purposes. For example, the path to one of the satellites may be obscured by a building while the path to a second satellite is relatively clear. Because both satellites are equipped with independent beacon signals, according to the present invention the user can select the satellite that provides greater opportunity for successful communications.

The exemplary UHF satellite communication system 100 includes a user communication device 104 with its own transceiver and antenna and a booster/high-powered antenna assembly 106 that provides a means of maintaining communications in adverse environments. The booster/high-powered antenna assembly 106 includes a more directive antenna (as compared to the antenna in the communication device 104) capable of increasing user performance and has additional transmitter power to boost the signal transmitted to the satellite. In a preferred embodiment, the booster/high-powered antenna assembly 106 is configured to have a simple plug-in connection with the user's transceiver.

However, if used indiscriminately, such a booster can degrade overall performance for other system users. For example, if used in relatively clear environments free from adverse conditions, the signal levels delivered to the satellite would exceed those levels needed to maintain communications. Such excessive levels can interfere with other system users degrading operation of the communication system. Thus, according to the present invention, the satellite beacon signals are also employed to provide a means for controlling the performance of the booster so that excessive performance does not degrade overall performance for other users. Other communication systems such as terrestrial cellular networks are also faced with some of the same limitations and would advantageously benefit from employing the principles of the present invention. Such a cellular system 200 is shown in FIG. 2 as a nominal cellular grid having a set of base stations 202 a, 202 b located within cells 204 a, 204 b, respectively. A user 206 within one of the cells may be blocked by a building and/or attenuated by foliage. In this case, service through a base station within an adjacent cell might provide improved communications and because the base stations would be furnished with similar independent beacon signals, the user would now be furnished with a means to select a base station that is more advantageous for communications.

When adverse communications are experienced in cellular systems, propagation limitations can be solved in particular situations. To obtain reliable communications in cellular systems, the user's transceiver can be equipped with an auxiliary jack to permit connection to a fixed antenna and amplification, similar to the booster/high-powered antenna assembly 106 of FIG. 1. Such a design can also control the transmitted power level so as to maintain communications and avoid excessive signal levels that degrade the performance of other cellular users. Also according to the invention, correlation of the received coded waveform with a reference replica of the code provides estimated values of the time delay components resulting from multipath. This information can be used advantageously to establish the time delay values needed in equalization. For the receiver, such equalization can be performed by an adaptive transversal filter comprised of complex weighting of time delay components. This equalization aligns the received time delay components to recover a signal undistorted by multipath. Also, an arrangement for determining the time delay for using an equalizer to mitigate the effects of multipath is disclosed in U.S. Pat. No. 5,781,845 to Dybala et al., incorporated herein by reference. In both cases, deriving estimates of the time delay values from the coded beacon signal can be used advantageously in techniques for equalization by independently estimating the required time delay values and thus reducing the time needed to implement the equalization.

The following discussion makes reference to UHF satellite communication systems; however, it should be appreciated that the principles of the present invention are not limited to this particular application. According to an exemplary method of the present invention, a plurality of UHF satellites is equipped with beacon transmitters that are designed to broadcast two types of signals to users of communications devices distributed over the earth's field of view. One of these signals is a CW tone, and the second type of signal is a low-level coded tone that preferably occupies the same bandwidth as the communication service. Referring to FIG. 5, which shows spectra received by a communications device according to an exemplary embodiment of the present invention, the CW tone (denoted "CW Beacon") is preferably separated from the bandwidths used by the communication traffic to avoid interference and loss of communication capacity.

The amplitude of the tone is controlled with sufficient accuracy to allow users to accurately measure link loss and scintillation, and the frequency of the tone is controlled with sufficient accuracy to permit users to measure their Doppler offsets. The second beacon signal (denoted "Coded Beacon") is coded to span the communication signals broadcast by the satellite and is transmitted at a sufficiently low level that the coded signal will not interfere with normal communications traffic. This signal is coded in a way that is known to the beacon transmitter and to the user receivers to afford protection from interference. Unlike other applications for satellite beacons that use CW tones, the present invention involves transmitting two types of signals, one a CW tone that is out of band and the second a coded signal within the communications bandwidth.

FIG. 3: is a functional block diagram of an exemplary space segment 300 according to the present invention. The illustrated space segment 300 includes the normal communication signals 302 that are up converted 304 to the transmit frequency, amplified to the transmitter output level, and routed to the downlink antenna 306 for transmission. The two beacon signal components 308, 310 are multiplexed with the communication signals 302. The CW beacon signal 310 is derived from a stable frequency reference 312 that is a normal part of the communication satellite transponder. The coded beacon signal 308 also uses this same frequency reference 312 in addition to the coded waveform that spans the downlink frequency allocation. Using the same frequency reference is advantageous because the CW beacon 310 detection assists in acquiring the coded beacon signal 308. More specifically, acquisition of the CW tone 310 corrected for Doppler offset provides the carrier reference for the coded beacon, which reduces the acquisition time for the coded beacon signal 308. Likewise, the CW beacon 310 facilitates determination of the Doppler offsets for UHF users located on moving platforms or in the event of satellites that are not in a geosynchronous orbit. In both cases, the Doppler offsets are significant because of the narrow channel assignments that subdivide the UHF frequency allocation.

A display for the user's communications device according to the present invention can take a variety of different forms, but generally includes a plurality of different fields that are preferably dedicated to and controlled by a processor to provide visible (or other human perceivable, e.g., audible, vibrating) indicia of link impairment and/or other information. Referring to FIG. 4, an exemplary display 400 suitable for employment with a communications device includes a signal-to-noise (S/N) meter 402, with red, yellow, and green zones, a noise level meter 404, an interference indicator light 406, a scintillation indicator light 408, and channel display 410 configured as shown. In the illustrated exemplary display 400, the S/N meter 402 and the noise level meter 404 comprise analog displays. The signal-to-noise ratio can be formed from the CW beacon power level and the noise level within the channel intended for system use or the noise power sampled from the out-of-band portion removed from the CW beacon signal. The signal to noise levels can be rationed with the noise levels when the receiver is terminated with a matched load. The ratio of these quantities is advantageous because absolute power levels are not required but rather a ratio that is independent of the receiver gain variations. In this example, the red, yellow, and green scales indicate when communication (link closure) is not possible, uncertain, and possible, respectively, allowing the user to intuitively determine communication feasibility. These zones can be repeated for different data rates allowing the user to determine the possibility of alternative services.

The separate noise level indicator 404 provides the user with an indication that communication may be limited by local noise. Such an indication is beneficial when the noise is locally generated, e.g., one noise source may be ignition noise from a vehicle and simply walking away from the vehicle may lower the noise sufficiently to allow communications. The separate displays 406 and 408 indicate the presence of interference and scintillation, respectively, advising the user of these link impairments. The channel displays 410, comprising light emitting-diode (LED) or any other display technology, provides a visible indication of what channel (defined or otherwise) is being evaluated. It should be appreciated that other forms of the display 400-whether providing more or less information-are also within the scope of the present invention.

FIG. 6: is a functional block diagram of a communications device that has been modified/augmented according to an exemplary preferred embodiment of the present invention to provide a user terminal equipment system 600 that, inter alia, receives and processes the beacon signals. The illustrated exemplary system 600 includes a communications device 602, a CW beacon receiver 604, a coded beacon receiver 606, a processor 608, a monitor 610, a transmitter power control 612, and a booster system 614 configured as shown. The illustrated exemplary communications device 602 includes a data receiver 616, a RF front end 618, a data modulator 620, a transmitter 622, a diplexer 624, and an antenna 626 configured as shown. A switch 628 interconnects the RF front end 618 to either the diplexer 624 or a reference load 630 depending upon the position of the switch 628 as controlled by the processor 608. Another switch 632 interconnects the diplexer 624 to either the antenna 626 or the booster system 614 depending upon the position of the switch 632 as controlled by the processor 608.

The processor 608 is programmed to control the communications device 602, the CW beacon receiver 604, the coded beacon receiver 606, the monitor 610 (to provide the user display 400), the transmitter power control 612, the booster system 614, and the switches 628, 632, and to process data from the CW beacon receiver 604, the coded beacon receiver 606 and the data receiver 616 in order to identify link impairment factors. The measured signal level provides several measures. The signal level provides a means of determining propagation loss, which can arise from several factors. Losses in the atmospheric path, losses caused by polarization conversion, losses caused by terrain and manmade structure blockage, and losses in foliage contribute to the measured loss. Changes in the location of communication equipment to reduce the last two loss factors allow users to seek a more favorable location as indicated by the signal level measurements.

The variation in the measured signal power (or variation in the measured signal level) indicates scintillation that degrades signal performance. This scintillation can arise from the ionospheric path or from multipath fading and again system performance is degraded. Monitoring these fluctuations at alternative locations, i.e., by viewing the monitor while moving the receiver, can help reduce the degradation caused by multipath fading. The signal levels of the CW tone and the coded signal can also be compared. The ratio of the two signal levels should have a fixed value. If the signal levels do not have the predetermined ratio (known nominal measured ratio taken in an interference free environment), the presence of interference is indicated. Interference within the bandwidth intended for the user's communication can be determined by measuring the noise level near the out of band CW tone and within the bandwidth intended for communications.

Both Galactic and manmade noise levels have significant variation at UHF frequencies, but what is important for communication availability is the ratio of signal and noise powers. Preferably, the measured noise power is used as a reference for the measured signal powers (i.e., S/N ratio). In this way, the link quality can be directly judged. Additionally, such a measurement is a relative one that can be made more accurately than an absolute one because the gain variations of the user equipment are removed by rationing the signal and noise levels. With regard to signal and noise measurements, the CW signal is out of band and its power can be measured by two separate techniques. A simple power meter can be used, but this measurement responds to the total power within the bandwidth including the tone power, noise power, and possibly interference power. The tone power can also be measured by squaring and integrating using a carrier recovery loop. In this way, noise components that occur in a power measurement are removed permitting high sensitivity measurements. The coded signal level is measured by correlating the received signal with a code replica present in the user's equipment. In these measurements, the integration time should be selected to be shorter than the fluctuation time of the scintillation so that variations caused by scintillation are not averaged and can be observed. The noise level near the out-of-band CW tone is also measured. The noise level within the user's intended bandwidth can also be measured to determine if the bandwidth is otherwise occupied.

The illustrated exemplary booster system 614 includes a power amplifier 634, a diplexer 636, a low-noise amplifier (LNA) 638, a second diplexer 640, and a high gain antenna 642 configured as shown. The booster system 614 provides a more directive antenna 642 than the antenna 626 with the communications device 602 (e.g., user's handset). An exemplary preferred antenna 642 for the booster system 614 is a log periodic antenna that can be inexpensively constructed. In addition to providing increased gain, the separate antenna 642 also provides isolation from the user avoiding antenna degradation such as body absorption. The diplexers 636, 640 at both the input and output allow separation of the additional power amplifier and preamplifier. According to the present invention, the received beacon power can also be used to control the user's uplink transmitted power level to avoid excessive signal levels that can degrade the performance of other users. By this means, the dynamic range of received signal levels at the satellite is reduced. In addition to determining link quality measures, by measuring the CW tone, Doppler offsets relative to the user can be determined. Compensation of these Doppler offsets provides a means of confining communications within the desired spectrum reducing interference to other system users. Lack of either signal or noise power measurements indicates malfunction of the user's receiver complementing Built-In Test Equipment (BITE) capabilities.

FIG. 7: is a flowchart illustrating a method 700 of determining communication link quality employing beacon signals according to an exemplary preferred embodiment of the present invention. Operation of the equipment system 600 can follow the steps of this exemplary method 700. At step 702, the receiver is terminated in the reference load 630 in order to establish the noise levels that are used as reference values in the subsequent determination of communication feasibility. With this termination, the receiver should respond to only the noise power, and the noise levels provide a set of reference levels used in subsequent decisions for operation. In practice, some variation of the absolute noise levels will be experienced because of the normal drift in the electronics gain values. However, such variation is relatively minor, probably less than 2 dB for practical designs.

Variation beyond these levels indicates receiver malfunction. At step 704, the measured noise levels are: the noise level output from the CW beacon receiver, the noise level from the out-of band (OOB) noise level adjacent to the CW beacon frequency, the noise levels in the data channels, and the noise level for the beacon coded signal correlator, which should be zero because the noise input to the receiver when terminated is not correlated with the code. At step 706, the consistency of these noise values is observed and a determination is made as to whether the receiver is malfunctioning. If it is determined that the noise levels are normal; and, therefore, the receiver is not malfunctioning, then at step 708 the receiver is switched to the antenna.

At step 710, the beacon power levels are premeasured at the same points when the receiver is connected to the antenna rather than the reference load. These signal levels are compared to the levels established by the noise measurements. The signal levels include those for both (all) satellites within the field of view and the alternative data channels available for communication with each. Again, because of the use of the reference load and rationing the measurements with the noise values, only relative rather than absolute signal levels are required in the present invention. The CW beacon outputs indicate the received power from each satellite and differences in these levels allow determining the more favorable satellite for use. The CW power measurements can be made using different integration times and observations (about particular defined channels, for example) can be made sequentially.

If the received beacon power is constant with time, scintillation and multipath fading are not present. Fluctuations in the power levels indicate multipath and/or scintillation; ionospheric scintillation is generally more rapid than multipath fading, and thus, by using different integration times the two effects can be separated. During this time, the coded beacon receiver 606 will undergo acquisition and its output similarly can be observed for different integration times to identify scintillation and multipath. In addition, one feature of the correlation processing used with the coded beacon is that it responds only to the coded signal and does not respond to either noise or interfering signals because these signals are not correlated with the code. By contrast, the CW beacon receiver responds to three possible signal components, the CW beacon signal of interest, noise components, and possible interference.

Thus, the coded beacon is advantageous because its output is independent of interference signals. Variations in the coded correlation indicate the presence of scintillation and/or multipath, and differences in the rate of variation of the correlation outputs allow distinguishing the limitations.

At step 712, the measurements made in the previous steps are used to decide on the ability to use the system for communications. For example, a determination is made as to which of two satellites within the field of view afford the best opportunity for communications. This decision can be made by examining the CW beacon power received from both satellites and the signal powers in the data channels shared between the satellites. The possibility exists that interference is present in the CW beacon signals; the presence of interference at this point is indicated by abnormally high signal levels detected at the beacon frequencies. In this event, the coded beacon power that is uncorrelated with interference and noise components can be used to determine the satellite that is most favorable for communications. At step 714, the next decision is to determine if the beacon signals have adequate strength to allow communications. The output of the CW and coded beacons are used for this purpose. The difference between the power levels of these two beacons also provides useful information. The CW beacon signal is comprised of three components, the signal, noise, and possible interference, while the coded beacon signal has only one component, the beacon signal because of the correlation benefits of the code. A ratio of these power levels indicates the presence of interference and/or excess noise. The beacon signals can also be used as a real time indicator of signal deficits. At step 716, the user can relocate to determine if manmade or terrain blockage is reducing the received beacon power. Foliage can also attenuate signals and relocating to a more favorable spot can increase the received beacon signal. Similarly, for handheld terminals, the beacon reception can be improved by some realignment of the terminal to reduce body absorption or antenna pattern degradation effects that degrade communications. Thus, the satellite beacons can be advantageously used to assist the user in determining a terminal location that allows a more favorable chance of communications.

At step 718, the potential presence of interference is addressed. Interference can limit system operation in several areas. The reception of interference in the CW beacon, the 00B CW noise sample, or the data channels can all limit terminal operation. The ratio of the CW and beacon power densities incident on the earth's surface is established in the satellite design. Without interference, the user should observe approximately the same ratio, and an excessive CW power level indicates interference at the CW frequency. Similarly, the 00B noise sample should vary over a credible range of antenna temperatures, and power levels in excess of this range indicate interference. Because noise generally has a broad bandwidth, the noise levels in the data channels should be similar to the 00B values, a further indication to identify interference in the 00B sample.

The data channels themselves can have signal levels comprised of normal system traffic, interference, and noise. A search through several of these channels should reveal the levels of the composite signals within each. The channels are allocated between the satellites to avoid mutual interference between users. Thus, the channel assignments between the two satellites within the field of view are known, and differences in received signal levels indicate channels being used, those with interference, and those containing only noise. A second source of interference that is observed by the user receiver is local terrestrial interference. Thus, the user should be able to find a channel that contains only noise to determine a reference level and also monitor the channel intended for use to determine if it is occupied, contains interference, and/or has a determinable noise level.

At step 720, the potential presence of scintillation is addressed. Scintillation is another link limitation and can arise from the ionospheric variation or from multipath. Monitoring both the CW and coded beacons over a time interval is used to determine the presence of interference. The received signal level variation of signal samples during the time interval indicates scintillation. If the signal level is steady, scintillation is minimal. The range of signal powers during the measurement intervals defines the amount of fading that can be translated to the anticipated loss in communication performance. The coded beacon signal will also have a reduced level because scintillation reduces the correlation of the beacon signal. Thus, another indication of scintillation lies with the ratio of the received CW and coded beacon signals. Multipath can be further distinguished by distinct peaks in the correlation response of the coded beacon.

At step 722, the potential presence of excessive noise is addressed. Excessive noise, typically from man-made sources, is another limitation. This noise level as described is determined from the OOB sample offset from the CW beacon and/or from those data channels that are not being used and do not contain interference. The noise levels are derived from the reference noise level when the receiver is terminated in a reference load, the noise level determined when the receiver is connected to the antenna, and the receiver noise temperature that is determined a priori. Having followed the above-described process, at steps 724 and 725 a decision is made with regard to the feasibility for communications. At this point, a data channel that is not occupied with other users or interference can be determined from the observed received signal level; this level should correspond to a credible antenna temperature. The signal level and the noise level have been established by the measurements. The amount of signal fading caused by ionospheric scintillation has also been determined. Thus, an estimate of the signal-to-noise ratio burdened by fading loss is established; this is one of the parameters indicated by the display 400. At this point, four possible outcomes exist: (1) communications are feasible; (2) communications at a reduced rate are feasible, (3) the use of a booster system is required, or (4) communications are not feasible at this time.

The display 400 is part of means for identifying these determinations (outcomes) and prompting user actions. For example, if the signal-to-noise (S/N) meter 402 is green at the monitor 610, the user can proceed with communications. If the signal-to-noise (S/N) meter 402 shows yellow, several alternatives are available. One alternative is to relocate to avoid blockage to the satellite path by buildings or foliage, or move away from the handset to reduce body absorption. The monitor 610 allows the user to observe changes in signal level and determine if relocation can allow communications. The user may also select the option of a reduced data rate service and thus reevaluate the possibility of communications. A further option is to use the booster system 614; attachment of the user terminal to the booster system 614 allows reassessment of communication options. Finally, if the monitor 610 is well within the red zone of the signal-to-noise (S/N) meter 402 in spite of the user's actions, then communication from the user's location is not feasible.

FIG. 8: shows an exemplary booster/high-powered antenna assembly 800 according to the invention. The booster component of the assembly 800 comprises an electronics package 802 containing a power amplifier, a low-noise amplifier, two diplexers (as discussed with reference to FIG. 6), and an input cable 804 connecting the existing transceiver and control cable for the power amplifier (as discussed with reference to FIG. 6), an antenna 806, and a tripod 808 or other mechanism to support and position the antenna 806. The booster enhances the terminal performance by providing an antenna having a higher gain performance than the existing transceiver and a higher transmitter power level. A variety of antennas could be used such as the Yagi design shown in FIG. 8. Because of its increased size, higher gain results boosting the received signal level on both received and transmit modes and providing circular polarization. Because the antenna 806 is separated from the user, body absorption degradation from the presence of operators is avoided and, where concerns of RF radiation hazards exist, this separation advantageously allows a higher transmitter level than can be accommodated by the user terminal itself. The connecting cable 804 has a control interconnection with the transceiver's processor to prevent excessive transmitted power when link impairments are minimal.

FIG. 9: shows the booster/high-powered antenna assembly 800 in a disassembled configuration with elements of the antenna collapsed and separately fitted into storage containers 810 a, 810 b, which provide means for storing the antenna for transit. An exemplary preferred antenna, particularly for long UHF wavelengths, comprises a plurality of sections that are configured to be assembled together, for example, using ferrules in the same manner as with a fly rod. The illustrated antenna sections each embody an arrangement where the elements comprising the Yagi antenna are spring loaded and collapse against the central axial element much like the ribs in an umbrella. In this way, the antenna can be stored for transit in, for example, a tube. When removed from the tube, the spring-loaded designs deploy the elements for operation.

FIG.10: of an exemplary system 100 in which the invention may be employed, a mobile vehicle 110 has mounted thereon a terminal system 120 that is adapted to communicate simultaneously with two satellites that are co-located in geostationary orbit. One satellite 130 is a direct broadcast satellite that provides television signals on a downlink at a frequency within a range assigned by an appropriate body, such as the Federal Communication Commission (FCC) in the U.S. or similar agency in Europe or other regions. A second satellite 140 is co-located with the first satellite and provides two-way data communication at uplink and down link frequencies that also are assigned by the FCC. As would be clear to one skilled in the art, a single satellite could provide both the television broadcast and two-way date communications services, and two or more satellites could be substantially co-located to provide such services. Effective communication from a single mobile in-motion terminal with multiple satellites would require the satellites to be within the beam width of the terminal antenna. In short, the features of the invention are not limited by the number of satellites engaged in the communication service.

In an exemplary embodiment relevant to the U.S., two-way data communications is provided by using one or more satellites in the U.S. Fixed Satellite Service (FSS) frequency band of 11.7-12.2 GHz for reception (downlink or forward link) and 14.0-14.5 GHz for transmit (uplink or return link) and simultaneous TV programs reception in 12.2-12.7 GHz Direct Broadcast Satellite

(DBS) or Broadcast Satellite Service (BSS) band from the same or close orbital location. The terminal system 120 includes an antenna 125 that is mounted on or into the roof of the vehicle and, preferably, has a low profile form that is attractive for application to mobile platforms, such as cars, sport utility vehicles (SUVs), vans, recreation vehicles (RVs), trains, buses, boats or aircraft. The lower profile facilitates terminal installation directly on or into the roof of the mobile platform, keeping the overall aerodynamic properties of the vehicle almost unchanged. The terminal system 120 also has a communications subsystem that is operative to provide the concurrent two-way data and television reception capability by appropriately processing the uplink and downlink signals at different frequency bands.

FIG.11: the transmit section comprises a flat active antenna array 1, polarization control device 24 up converter unit 23. High power amplifiers (HPA) 2 modules are integrated directly to each one of the array inputs in order to minimize signal losses between the up-converter unit 23 and radiating elements of the array 1. The transmit signal formed in the IF/baseband transceiver block 21, which also is disposed on rotating platform 11, is up converted in a standard up-converter unit 23 and then transferred through polarization control device 24 to the transmit panel inputs. The polarization control unit 24 comprises electronic controlled phase controlling devices and attenuators, which are operative to control the amplitude and phase of the signals applied to each one of the antenna array inputs (or integrated with the antenna array/sub array elements).

The vertical (V) and horizontal (H) polarized outputs of the polarization control unit 24 are connected properly through two independent feed networks to each one of the two port sets of the dual port radiation elements. This arrangement, can effect control of the polarization tilt of the transmitted linearly polarized signals. Specifically, the required polarization offset can be established, depending on the vehicle location with respect to the selected satellite, using the information from a GPS module 18 and possibly an inclination sensor 29. Polarization tilt information may also be obtained by monitoring the cross polarized channels of the satellite.

FIG.12: at an antenna coupled to a mobile terminal mounted on a vehicle in motion (e.g., car, truck, or the like suitable for carrying a low profile antenna), at least one of direct broadcast television signals and data communication signals, which are transmitted by satellite at a location in geostationary orbit, are received (step S1). At the mobile terminal the orbital location of the one (or more satellites in substantially the same location, within the beam width of the mobile terminal antenna) is identified (step S2), preferably using an RSSI module or similar location identification technique, on the basis of received TV or data signals. Then (step S3), the (preferably low profile) antenna on the terminal is adjusted in at least one of azimuth and elevation so that it is pointed to the orbital location of the satellite(s) while the vehicle is in motion. Finally, data is transmitted to the satellite(s) from the antenna while the vehicle is in motion (step S4). Preferably, the terminal is adapted to concurrent reception of data and television signals.

Claims

WE CLAIM

1. Our Invention "IPCM- Movable Satellite: is an intelligent propagation impairment for Movable Satellite Communication Links at the Microwave Frequencies in Location" is a method of determining communication link quality includes the steps of providing communications stations and VHF/UHF Software Communications Satellites, base stations of a terrestrial cellular network with beacon transmitters that are used to transmit two types of signals from each communications station and providing a communications device that employs the communications stations with beacon receivers and the ability to process the two types of signals to provide a user of the communications device with a real time determination of link impairments and, from this, a determination of the type and quality of service that is available to the user. The invented technology also a multiple ground station and one or more stellites for communicating between mobile subscribers and a land-based communications network, such as the global/PSTN or the Internet. The multiple ground stations geographically dispersed minimize tool charges incurred routing calls from a mobile subscriber through the land network by reducing the need for long-distance calling. The station communicates with a given satellite using the same frequency spectrum, the subscriber capacity of the system increases and/or bandwidth requirements for the communications link between ground stations and satellites may be as per user required they can have reduced. The ground-based beamforming techniques enabling each satellite to transmit signal in multiple transmission beams, each beam supporting one or more mobile subscribers. Each beam may reuse the same frequency spectrum, thereby increasing the number of subscribers supported by each satellite. Multiple ground stations cooperatively relay signals through a given satellite in a manner complementary with ground-based beamforming. A low profile mobile in-motion antenna and transmit/receive terminal system for two-way"VSAT" type satellite communication using FSS service, preferably in Ku band, supporting at the same time TV signal reception from the same satellite or a separate DBS satellite located at the same or nearby geo-stationary orbital position. The "IPCM- Movable Satellite" first type of signal is a stable continuous wave tone that provides a reference signal level and the second type of signal is a coded waveform with distinguishable correlation properties and also the invented technology a processor and display are integrated with the user's communication device and function to process these two signals and provide a user-friendly interface through which information pertaining to determined levels of link impairments and the type and quality of service available at that given location and time is communicated to the user. The user's communication device is also provided with a booster system with an alternative high-gain antenna to increase communications opportunities in difficult operating environments.

2. According to claims# the invention a method of determining communication link quality includes the steps of providing communications stations and VHF/UHF Software Communications Satellites, base stations of a terrestrial cellular network with beacon transmitters that are used to transmit two types of signals from each communications station and providing a communications device that employs the communications stations with beacon receivers and the ability to process the two types of signals to provide a user of the communications device with a real time determination of link impairments and, from this, a determination of the type and quality of service that is available to the user.

3. According to claiml,2# the invention a The invented technology also a multiple ground station and one or more stellites for communicating between mobile subscribers and a land-based communications network, such as the global/PSTN or the Internet. The multiple ground stations geographically dispersed minimize tool charges incurred routing calls from a mobile subscriber through the land network by reducing the need for long-distance calling.

4. According to claiml,2,3# the invention a low profile mobile in-motion antenna and transmit/receive terminal system for two-way"VSAT" type satellite communication using FSS service, preferably in Ku band, supporting at the same time TV signal reception from the same satellite or a separate DBS satellite located at the same or nearby geo-stationary orbital position.

5. According to claiml,2,3# the invention a method of determining communication link quality includes the steps of providing communications stations (e.g. UHF communications satellites, base stations of a terrestrial cellular network) with beacon transmitters that are used to transmit two types of signals from each communications station.

6. According to claiml,2,4# the invention to a providing a communications device that employs the communications stations with beacon receivers and the ability to process the two types of signals to provide a user of the communications device with a real time determination of link impairments and also the invention to a determination of the type and quality of service that is available to the user. The first type of signal is a stable continuous wave tone that provides a reference signal level and the second type of signal is a coded waveform with distinguishable correlation properties.

7. According to claiml,2,3,5# the invention to the invented technology a processor and display are integrated with the user's communication device and function to process these two signals and provide a user-friendly interface through which information pertaining to determined levels of link impairments and the type and quality of service available at that given location and time is communicated to the user.

8. According to claim,2,5# the invention to the user's communication device is also provided with a booster system with an alternative high-gain antenna to increase communications opportunities in difficult operating environments and also the invention to a wherein the communication device comprises a transponder. The invention to a wherein the communication device comprises at least one of a mobile voice communicator and a mobile data communicator.

9. According to claim,2,5# the invention to a wherein the means for receiving and processing the beacon signals comprises a processor. The invention to a wherein the means for receiving and processing the beacon signals comprises one or more beacon receivers. 10.According to claim,2,4,7,8# the invention to a wherein the one or more beacon receivers comprise a continuous wave (CW) tone beacon receiver. The invention to a wherein the one or more beacon receivers comprise a coded signal beacon receiver and also the invention to a wherein the means for communicating information provides a real time indication of link quality.

FIG. 1: IS A DIAGRAM ILLUSTRATING AN EXEMPLARY IMPLEMENTATION OF THE METHOD OF THE PRESENT INVENTION FOR A COMMUNICATIONS DEVICE AND A PLURALITY OF COMMUNICATIONS SATELLITES.

FIG. 2: IS A DIAGRAM ILLUSTRATING AN EXEMPLARY IMPLEMENTATION OF THE METHOD OF THE PRESENT INVENTION FOR A COMMUNICATIONS DEVICE AND A TERRESTRIAL CELLULAR NETWORK.

FIG. 3: IS A FUNCTIONAL BLOCK DIAGRAM OF AN EXEMPLARY SPACE SEGMENT.

FIG. 4: IS AN EXEMPLARY DISPLAY SUITABLE FOR EMPLOYMENT WITH A COMMUNICATIONS DEVICE.

FIG. 5: IS A DIAGRAM OF SPECTRA RECEIVED BY A COMMUNICATIONS DEVICE.

FIG. 6: IS A FUNCTIONAL BLOCK DIAGRAM OF A COMMUNICATIONS DEVICE MODIFIED ACCORDING TO AN EXEMPLARY PREFERRED EMBODIMENT OF THE PRESENT INVENTION;

FIG. 7: IS A FLOWCHART ILLUSTRATING A METHOD OF DETERMINING COMMUNICATION LINK QUALITY EMPLOYING BEACON SIGNALS.

FIG. 8: SHOWS AN EXEMPLARY BOOSTER/HIGH-POWERED ANTENNA ASSEMBLY.

FIG. 9: IS AN EXEMPLARY EMBODIMENT OF THE BOOSTER/HIGH-POWERED ANTENNA ASSEMBLY IN A DISASSEMBLED CONFIGURATION WITH ELEMENTS OF THE ANTENNA COLLAPSED AND SEPARATELY FITTED INTO STORAGE CONTAINERS.

FIG.10: IS AN ILLUSTRATION OF A COMMUNICATIONS SYSTEM WITH WHICH THE PRESENT INVENTION IS EMPLOYED.

FIG.11: IS A BLOCK DIAGRAM OF THE MOBILE ANTENNA TERMINAL IN ACCORDANCE WITH THE EMBODIMENT OF THE INVENTION.

FIG.12: IS A FLOW CHART OF AN EXEMPLARY PROCESS PERFORMED IN THE IMPLEMENTATION OF THE PRESENT INVENTION.