Abstract: A system and method for establishing a communication link, wherein the system includes a communications unit (60, FIG. 3) having a vocoder (62) for providing user-specific voice data in the form of a unique set of speech characteristic model parameters for each authorized user. The method (200, FIG. 8) includes the steps of providing user-specific voice data via a connection training method (FIGS. 5, 6, or 7), collecting a sample of speech characteristics from a user desiring to access the communication unit (206, FIG. 8), comparing the sample with the user-specific voice data (212), granting the user access to the communication unit to establish a communication link with another communication unit if the sample is comparable with the user-specific voice data (215), and denying the user access to the communication unit if the sample is incomparable with the user-specific voice data (220).

Abstract: A method and apparatus for combining and separating groups of signals starts by a transmitter (500) receiving a number of CDMA-encoded signals from data sources (510). The CDMA-encoded signals are sorted (502) based on their intended destinations. Those CDMA-encoded signals which are intended for a common destination are multiplexed (504) together into a group. The group is further CDMA encoded (506) using a group code and the encoded group is transmitted (508) to an intermediate transceiver (600) or a destination transceiver (700). The intermediate or destination transceiver decodes (604, 704) the group using the appropriate group code and routes the resulting group of signals accordingly.

Abstract: A secure computer system (100) includes a host processor (105) for communicating a datum to a trusted bus (101). A bridge (125) connects the trusted bus (101) to an untrusted bus (102). The bridge (125) conveys the datum from the trusted bus (101) to the untrusted bus (102). A bus access monitor (200) is coupled to the trusted bus (101) and the untrusted bus (102). The bus access monitor (200) performs a method (1000, FIG. 10) for securely monitoring the untrusted bus (102), and asserting an alarm signal when address information associated with the datum fails to compare with predetermined address information. Additionally, the host processor (105) performs a method (300, FIG. 3) for self-testing the bus access monitor.

Abstract: A communication satellite system (100) is established using one or more satellite constellations (110, 120). The two or more satellite groups (110, 120) are connected via long range crosslinks (145) which provide a communication path between the long range satellites (150, 170) in the two satellite groups (110, 120). Each satellite group (110, 120) comprises long range satellites (150, 170) and short range satellites (160, 180) which are interconnected using short range crosslinks (155, 175). A single antenna on each satellite provides both crosslinks. The long range crosslink (145) is established using the antenna's main beam and the short range crosslinks (155, 175) are established using the antenna's sidelobes.

Abstract: An antenna subsystem (120) which comprises an electronic scanning reflector antenna (400) is used for the formation of single and multiple beams. Reflecting surface (420) is covered with at least one dielectric layer (430) which is used to simultaneously and independently steer multiple beams. Electronic scanning reflector antenna (400) operates similar to a phased array antenna. ESRA (400) comprises a number of independent controllable reflecting surfaces (450) which are combined together in close proximity. Each one of the individual regions is covered by a dielectric layer, and the dielectric constant for each can be independently controlled. Electronic scanning reflector antennas (400, 600) are used in both space-based and terrestrial-based applications. Electronic scanning reflector antennas (400, 600) are used for both transmission and reception of electromagnetic signals.

Abstract: An array (100) of voltage variable capacitors (110) is provided in which voltage variable capacitors (110) are fabricated with piezoelectric displacement devices (150). Voltage variable capacitors (110) have first plates (120) which are coupled to displacement devices (150). First plates (120) are dielectrically coupled to second plates (130). Displacement device (150) has a stack of metallic layers (154), voltage variable material blocks (152), and voltage supply terminals (170) and (180). Voltage differences are established across voltage variable material blocks (152) using voltage supply terminals (170) and (180). A voltage difference causes a voltage variable material layer to change thickness, and this causes first plate (120) to move relative to second plate (130). Voltage variable material is selected from a group of piezoelectric ceramics, which can include lead-titanate (PbTiO.sub.3), lead-zirconate (PbZrO.sub.3), barium-titanate (BaTiO.sub.3), and lead-zirconate-titanate (PbZr.sub.x Ti.sub.1-x O.

Abstract: Message information is sent from an origination node to a destination node through a number of route-processing nodes (300). Routing/processing codes are determined for the number of route-processing nodes (300), and a destination code is determined for the destination node. Signal routes from origination nodes to destination nodes are determined in terms of multi-level paths. Different codes are used to identify the different path levels. Data that is to be sent to a particular user located at a destination node is first spread using the destination code for that destination node. This spread spectrum signal is spread a second time using a first routing/processing code. In addition, the data can be spread a number of additional times using a number of routing/processing codes. Route-processing nodes (300) receive and partially decode signals. During the transmission of the spread data, decoding processes are performed, and the decoded data is routed based on the results of these decoding processes.

Abstract: Switchable nodes (300), such as satellites (20,21) and/or gateways (40,41), along with a modified call setup procedure are used in satellite communication system (100) to prevent fraudulent users from misusing resources by not allowing those resources to be available until the call setup procedure is completed. Also, both satellites and gateways monitor traffic to determine when unauthorized traffic is occurring. Switchable nodes (300) can intercept calls for both monitoring and control purposes and deny access to fraudulent and suspicious users and communication units.

Abstract: A phased array antenna (1000) is formed using a number of independently controllable piezoelectric phase shifters (1300) which results in a low cost phased array antenna that is functional at microwave and/or millimeter wave frequencies. In addition, the independently controllable piezoelectric phase shifters (1300) have sufficient phase range to allow a single antenna to be steered over a wide angle field of view. Piezoelectric phase shifters (1300) comprise at least one-voltage variable capacitor (1310, 1320, FIG. 2). Typically, the piezoelectric material used in the voltage variable capacitors is selected from a group consisting of lead-titanate (PbTiO.sub.3), lead-zirconate (PbZrO.sub.3), barium-titanate (BaTiO.sub.3), and lead-zirconate-titanate (PbZr.sub.x Ti.sub.1-x O.sub.3), where x varies from zero to one.

Abstract: A harmonic generator (20) converts an input signal (24) at a fundamental frequency (28) into an output signal (32) at a harmonic frequency (34). A non-linear device (22) converts the input signal (24) into an intermediate signal (38) in which the harmonic frequency (34) has a maximized amplitude (40) determined by a conduction angle (26). A harmonic filter (68) produces a filtered signal (70) proportional to the amplitude (40) of the harmonic frequency (34) within the intermediate signal (38). A detector (80) produces a control signal (82) proportional to the amplitude of the filtered signal (70). A control circuit (84) produces a variable bias signal (50) for non-linear device (22), bias signal (50) being proportional to the amplitude of the control signal (82) and determining the conduction angle (26). An output filter (88) converts the intermediate signal (38) into an output signal (32) at the harmonic frequency (34).

Abstract: Additional resources and services are provided in a satellite communication system (100) through the use of seam satellites (52). One or more seam satellites (52) are coupled to communication satellites (12) in an existing constellation using previously unused crosslinks. The seam satellites (52) are located between orbital planes (31 and 36) in which the communication satellites (12) are moving in opposite directions with respect to each other. Seam satellites (52) can provide new services such as earth sensing and observation. Seam satellites (52) can also provide attachment points for other new space-based users. Some of the communication units (26) can communicate with the seam satellites (52) via communication satellites (12). This allows these communication units (26) to use the new services provided by the seam satellite (52). Seam satellites (52) can be controlled by separate control centers or can be controlled by the control center for the communication satellites (12).

Abstract: A communication system including a constellation of satellites and a multi-channel unit having a plurality of co-located transceivers operative for exchanging communication information with users, and for monitoring a plurality of spot beams transmitted from one or more of the satellites for ring alert data contained within broadcast channels, and for monitoring and prioritizing the strongest of "n" broadcast channels for ring alerts based upon signal strength, upon a continuous sampling of ring alert channels contained within one or more broadcast channels, upon broadcast signal strength in relation to idle transceiver availability and the communication system geometries, and upon the monitoring of broadcast channels contained within candidate handoff lists contained within one or more of the traffic channels of in-use transceivers, for the purpose of increasing the probability of receiving a ring alert.

Abstract: Signal routing from origination nodes (210) to destination nodes (250) in a spread spectrum communication system (100) is provided using spread spectrum routing codes. Origination nodes (210) and destination nodes (250) are identified using specific codes. Signal routes from origination nodes (210) to destination nodes (250) are determined in terms of multi-level paths. Different codes are used to identify the different path levels. Data that is to be sent to a particular user located at a destination node is first spread using the destination code for that destination node. This spread spectrum signal is spread a second time using a first-level path code. In addition, the data can be spread a third time using a second-level path code. During the transmission of the spread data decoding processes are performed and the decoded data is routed based on the results of these decoding processes.

Abstract: The invention describes a method and system for the calibration of sectionally assembled phased array antennas. When a large, multi-sectioned phased array antenna on board a satellite (10, FIG. 1) is unfolded during deployment, an error in the alignment of a phased array antenna section (25) can cause an error in the pointing angle of the transmit antenna beam (50). A suitable receive antenna (80) receives a signal from the transmit antenna beam (50) which enables a processor unit (95, FIG. 2) to determine the required correction factor. The correction factor is then applied to the beam coefficients which control the beam of the phased array antenna section (25). Subsequent to a first measurment, the correction factor can be updated to minimize the impact of antenna element failures on the resulting antenna pattern.

Abstract: A communication system (10) includes a population of mobile units (24) which communicate with a control station. Communications take place between the control station and the mobile units (24) so that the system (10) may gain knowledge about the mobile units' locations. The mobile units (24) occasionally initiate such communications automatically. The control station sends data defining a target area (72, FIG. 5) to the mobile units. The mobile units (24) reside in the target areas (72) when the target areas (72) are first assigned, but the mobile units (24) are free to move. The control station transmits broadcast signals to geographically spaced apart cells (36, FIG. 2). The broadcast signals convey current data identifying the service areas covered by the cells (36). The mobile units (24) automatically initiate communications when their assigned target areas (72) do not coincide with the service areas for the broadcast signals they can receive.

Abstract: Multiple, different, independent constellations (10, 20) of satellites (2, 21-23) share a portion of a common frequency spectrum such as a single carrier frequency. The satellites' antennas (11) may be either multi-beam or omni-directional, while those of earth stations (13, 14) are directional. When interference occurs between communications of a satellite (31) of a first constellation (10) and a satellite (41) of a second constellation (20), any of several interference-mitigation options may be employed, such as the first satellite (31) handing off communications to a second satellite (32) of the same constellation (10), or temporarily suspending communications. The remedial action may occur in response to either predicted or detected interference.

Abstract: An integrated microstrip (14) to suspended stripline (24) transition structure and method for fabricating the same provide a transition from microstrip (14) to suspended stripline (24) transmission line with minimal electrical discontinuity and insensitivity due to misalignment. A conductor (10) has a constant width, while gradually tapering voids (44,42) in ground planes (36, 38) provide a suspended stripline (24) transmission medium. The gradually tapering voids (44, 42) provide impedance transformation and minimize discontinuities during transition due to fabrication tolerances.

Abstract: A satellite attitude/orbit control system (300) for managing a satellite cluster (200) in a satellite constellation (207). A satellite cluster (200) comprises a master satellite (203) and secondary satellites (201, 202, 204, 204). The master satellite (203) receives sensor data from secondary satellites (201, 202, 204, 204) and combines such secondary sensor data with master sensor data from a master satellite (203) to calculate attitude/orbit estimates for all satellites within the satellite cluster (200). Attitude estimates are forwarded to each satellite for initiation of attitude/orbit control. Each satellite cluster (200) subordinates to a constellation master satellite (301) for receiving additional attitude/orbit estimates for use in determining and controlling satellite attitude/orbits.

Abstract: A communication system (100) includes satellites (102,104) and a mobile exchange unit (MXU) (120) for exchanging communication information with users. A satellite (102) generates synchronous timing frames requiring users operating through an MXU (120) to anticipate timing and frequency requirements to participate in communications. An MXU (120) must advance transmissions to a satellite (102) to insure transmissions arrive at satellite (102) within the proper synchronous receive window. Such advanced transmissions by MXU (120) interfere with reception of a ring alert/page transmission (130) which contains the location of broadcast channels (86) designating an incoming call or page data transmissions. The MXU (120) alternatively extracts a broadcast channel location from a candidate hand-off list being transmitted by a satellite (102) to in-use transceivers (310). The MXU 120 then distributes the location of the broadcast channel to those transceivers (310) presently not in-use.

Abstract: A numerically controlled oscillator (11), (NCO), generates an NCO output (114) having a time-averaged frequency proportional to a rational number, even if the number of bits in the binary frequency control numbers (104, 106) is insufficient to represent the fractional part of the rational frequency number precisely. Frequency control numbers (104, 106) alternate between numerically adjacent values proportional to the desired time-averaged rational frequency control number. Frequency control numbers and their duty cycles are calculated for synthesizing a time-averaged rational frequency.