Abstract: Authorized intercepts of communications in a communications system such as a satellite communications system (10) are controlled. Each law enforcement agency (LEA) can only intercept communications to subscriber units (SUs) within its jurisdiction. In addition, the identity of each authorized intercept target is known only to the requesting LEA. In one embodiment, a trusted entity, such as a network operations facility (NOF 22, FIG. 3), creates a list of ID's corresponding to all SUs within each LEA's jurisdiction. Each SU ID is provided both unencrypted and encrypted for one or more network nodes (NN 1-R, FIG. 3). A network intercept facility (IF 201, FIG. 3) selects a target SU ID, generates an intercept order encrypted for one or more NNs, and sends it to one or more NNs for execution.

Abstract: A satellite communications system (10) provides for digital beamforming acquisition. The communications system (10) has an antenna configuration (20) for maintaining communications links with satellite networking equipment, and a signal processing system (30) for processing signals resulting from the communications links. A beamforming subsystem (40) dynamically forms traffic beams and overhead beams, wherein the overhead beams scan overhead areas of the satellite footprint. Overhead areas are defined by areas of the satellite footprint without active traffic channels. The beamforming subsystem (40) includes a channel database configuration (50) containing traffic channel input data and overhead channel input data. A beamforming processor (60) converts the input data contained in the channel database configuration (50) into traffic beams schedules and overhead beam schedules. An antenna management system (70) dynamically forms traffic beams and overhead beams based on the beam schedules.

Abstract: A ground-based antenna assembly (10) is provided that includes an assembly base (14) defining a substantially horizontal plane (18) and configured for attachment to a residential, commercial or governmental structure. The ground-based antenna (10) also includes a plurality of planar receiving panels (22) having a circular and/or elliptical shape. The plurality of planar receiving panels (22) are radially-spaced about the assembly base (14) and tilted with respect to the substantially horizontal plane (18) for a receiving field-of-view. The ground-based antenna assembly (10) further includes a plurality of planar transmitting panels (26) having a circular and/or elliptical shape. The plurality of planar transmitting panels (26) are radially-spaced about the assembly base (14) and tilted with respect to the substantially horizontal plane (18) for a transmitting field-of-view.

Abstract: A power amplifier core (40) for amplifying RF signals is provided. The power amplifier core (40) includes a first string of FET cells (46) for amplifying the RF signal. The FET cell string includes at least two FET cells (46) connected in series with an output port (48) of the amplifier core. A bias network (44) coupled between an amplifier core input port (42) and the FET cells (46) couples the RF signal to the FET cells (46). The bias network (44) includes a bias capacitor (50) and a resistor network. The bias capacitor (50) is coupled to the input port (42) for AC coupling the RF signal to an associated FET cell (46) in the FET cell string. The resistor network is coupled from the bias capacitor (50) to the associated FET cell (46) for providing a DC bias to the associated FET cell (46).

Abstract: A method (300, FIG. 3) controls CU (140, FIGS. 1, 6) hand-off in a non-geostationary orbit (NSGO) satellite system (100, FIG. 1) without consuming large amounts of bandwidth or satellite processing power. Using method (300), a network control facility (NCF) (130, FIGS. 1, 5) divides the earth (102, FIG. 2) into suitable regions 200 (FIG. 2), or geographical areas of the earth sized so that all of the CUs (140, 142, 144, FIG. 1) within a region (200) can be handed-off as a group rather than handling each station individually. When it is determined through the method (300) that it is time to hand-off communications in a particular region, all CUs within that region are directed to effectuate a hand-off at substantially the same time.

Abstract: An amplifier circuit (100) includes a power amplifier (124) that has a modulated power supply input (125). The modulated power supply input (125) is modulated with a signal related to the amplitude of the signal being amplified by the power amplifier (124). The power amplifier (124) is maintained at a substantially constant operating point. The amplifier circuit (100) also includes a feedback path that generates an error signal as a function of the input signal envelope and the output signal envelope. The error signal is integrated and the resulting integrated error signal drives the gain control of a variable gain element (120) in the amplifier chain prior to the power amplifier (124).

Abstract: A product detector for converting a signal to baseband includes a commutating switch which serves to sample an RF waveform four times per period at the RF frequency. The samples are integrated over time to produce an average voltage at 0 degrees, 90 degrees, 180 degrees and 270 degrees. The average voltage at 0 degrees is the baseband in-phase signal, and the average voltage at 90 degrees is the baseband quadrature signal. Alternatively, to increase gain, the 0 degree average can be differentially summed with the 180 degree average to form the baseband in-phase signal, and the 90 degree average can be differentially summed with the 270 degree average to produce the baseband quadrature signal.

Abstract: An electronic package (10) designed to be mounted in a space vehicle includes active electronic components that produce heat energy during operation and has a shear plate (12) attached to a heat sink (13). A heat spreader (11) includes an L-shaped plate of thermal pyrolitic graphite encapsulated in aluminum, which has a long arm (20) attached to the shear plate (12) by a heat conductive adhesive and a short arm (21) attached to the heat sink (13) for transferring heat energy from the package (10) to the heat sink (13). Whereby the heat sink (13) and the package (10) produce a dynamic load and the heat sink (13) and the package (10) are designed to carry the dynamic load with the heat spreader (11) providing only thermal enhancement.

Abstract: A system (8) for digital processing of optical image data includes a wavelet decomposition unit (12) for decomposing an input image (10) into a plurality of frequency subbands. Each subband is then converted to a frequency domain representation, phase scrambled, and then converted back into a time domain representation in a phase scrambling unit (14). The subbands are then subject to trellis coded quantization (TCQ) in a trellis coded quantization encoding unit (16, 40) before being transmitted into a channel (28). In one embodiment, fixed rate trellis coded quantization (FRTCQ) is used in a communications system having a relatively noiseless channel.

Abstract: A planar array antenna for use with an earth-based subscriber unit generates receive or transmit communications beams through the use of digital beamforming networks (210, 211) which provide beam steering in a first dimension. In another dimension, the communications beams are synthesized by way of a waveguide structure (300, FIG. 3) which is repeated for each row of the antenna array. The waveguide outputs are weighted due to the positioning of coupling slots (350) or coupling probes (450) which transfer carrier signals to and from each waveguide. The slots or coupling probes from the waveguides are coupled to a group of barium strontium titanate (BST) (360, FIG. 3) or micro-electromechanical systems (MEMS) switch (460, FIG. 4) phase shift elements which are under the control of a control network (221, 222, FIG. 2). The resulting signals are radiated by the antenna elements of the planar antenna array (310, FIG. 3) to form a communications beam.

Abstract: A hybrid geostationary and low earth orbit (LEO) ground station antenna provides a geostationary receive antenna (30) which generates a narrow receive antenna beam for use with geostationary satellites. The ground station antenna can be either manually positioned so that the normal boresight of the antenna is directed toward the geostationary satellite serving the subscriber, or may be positioned using a cradle (170) which provides motion in the pitch, roll, and yaw axes. The ground station antenna also includes a LEO receive antenna (40) and a LEO transmit antenna (50) which receive which communicate with LEO satellites by way of wider beam, lower gain antenna beams. The geostationary receive antenna (30) is used in conjunction with the LEO satellites and during operations which involve communication with both types of satellites.

Abstract: A method and apparatus for efficient power amplification of a wideband signal with a correspondingly wide modulation bandwidth includes an envelope detector (220), an adaptive split band modulator (270), and a power amplifier (260). The adaptive split band modulator (270) amplifies the low frequency components using a class S modulator (760), and amplifies the high frequency components using a class B amplifier (750). The power supply of the class B amplifier (750) is adaptively modified as a function of the amplitude of the signal that it amplifies. In this manner, the class B amplifier (750) operates at a higher efficiency.

Abstract: A power amplifier uses a plurality of solid-state amplifiers (FIGS. 2 and 3, 140) arranged in a parallel manner to form a power amplifier module (10). Each solid-state amplifier is adhered to a low thermal expansion insert (130). The insert is then coupled to a low cost aluminum substrate in order to carry the excess heat from each solid-state amplifier (140) to the aluminum housing. The power outputs from the solid-state amplifiers from each module are combined with the power outputs from other modules using electroformed waveguide combiners (FIG. 1, 30, 40).

Abstract: A transmitter system (18) which transmits a communication signal (14) through a phased-array antenna (10) uses a signal processor (26) and a multiplicity of direct modulators (30). Each direct modulator (30) drives a single element (12) of the antenna (10). Each direct modulator (30) receives a digital baseband phase point data signal (62) from a digital data stream (28). The digital data stream (28) also conveys digital beam formation data (60). Each direct modulator (30) digitally combines the baseband phase point data (62) with the beam formation data (60) to produce digital streams that modulate an RF carrier signal (34). The digital data stream (28) is generated by a phased-array signal processor (26) which processes user data bits (86) received from any number of input signals (22) and processes beam signals (24). In one embodiment, the signal processor (26) calculates phase point data (62) representative of all input signals (22).

Abstract: A method and apparatus for efficient power amplification of a wideband signal with a correspondingly wide modulation bandwidth includes an envelope detector (220), an interleaved class S modulator (270), and a power amplifier (260). The interleaved class S modulator (270) amplifies includes multiple channels (272) which each include a portion of a class S modulator. Each class S modulator has a duty cycle and time offset associated therewith. The duty cycles of the channels (272) can be the same with the time offsets different, or the duty cycles can also be different. For an interleaved class S modulator with N channels (272), the slew rate increases by as much as N, and the output ripple decreases by as much as N.sup.2.

Abstract: In a mobile communications system (10), system (10) through base station (40) or one or more satellites (20) monitors bandwidth availability and determines acquisition channel resource information. The system (10) broadcasts the acquisition channel resource information to the mobile units (30) via satellite (20). According the acquisition channel resource information, the mobile units (30) are enabled at select time instances to access the acquisition channel, obtain a traffic channel and transmit their messages to base station (40). Thus, mobile units (30) are enabled to access system (10) when resources are available.

Abstract: A communications network (10) having a plurality of wireless nodes (12-28) distributed within a region of interest makes routing decisions based on terrain information for the region of interest. A link quality determination unit (54) determines the quality of individual node-to-node links within the network (10), based on the location of the nodes (12-28) and the terrain about the nodes (12-28). A path selection unit 58 then determines an optimal path through the network 10 based on the link quality information. In one embodiment, communications corridors (102) are defined as preferred subpaths within a network for use in connecting remote nodes.

Abstract: A method and apparatus for providing an economically viable satellite communication system (100) for voice, data, and video using satellite diversity to augment capacity of the system, to mitigate the effects of network operational issues such as the effects of satellite failure and/or satellite blockage, and to maintain service links (180) in a cost-effective manner. Satellite diversity is incorporated into the communication architecture, along with the ability to utilize all satellites (110) within a communication range (or view) of one or more service regions (197). Management methods are used to allocate satellite diversity to enhance service and mitigate network operational issues. Satellite constellation (120) is designed to maximize the availability of satellite diversity as a resource.

Abstract: A method and apparatus for authenticating subscriber units (30) and users (25) in a communications system includes a communications node (200) which receives biometric information describing a user (25), and measures an RF signature of the subscriber unit (30). The biometric information and RF signature are compared against a valid user profile to determine authenticity of the user (25) and the subscriber unit (30). The biometric information can include retinal scan data, fingerprint data, or other data. The RF signature can include spectral content, phase or frequency characteristics, or other identifying features.

Abstract: A method and apparatus for efficient power amplification of a wideband signal with a correspondingly wide modulation bandwidth includes an envelope detector (220), a soft switch modulator (270), and a power amplifier (260). The soft switch modulator (270) drives a high side switch (330), and a low side switch (340) to amplify a pulsewidth modulated signal. Electrical signal path lengths within a soft switch driver (320) are dynamically modified so as to always turn off one switch before turning on the other.