Abstract: A method and apparatus for acquiring satellite signals and subscriber unit signals utilizes broadcast beams (205) and acquisition beams (215) projected from a satellite (20). The broadcast beams (205) and acquisition beams (215) form broadcast acquisition beam pairs that are swept within the footprint (50) of the satellite (20) on the surface of the earth. Broadcast bursts are transmitted by the satellite (20) in the broadcast beams (205), and acquisition bursts broadcast by subscriber units (30) are received by the satellite (20) in acquisition beams (215).

Abstract: A method and apparatus for soft decision propagation trades off system bandwidth in return for link margin. When signal quality on an uplink is low, a satellite (20) sends soft decision data, rather than hard decision data, to a gateway (40). When path diversity exists on the uplinks, and multiple satellites (20) receive the uplink, multiple versions of soft decision data are sent to the gateway (40). The gateway combines the soft decision data resulting from multiple uplink paths, thereby increasing the effective uplink signal to noise ratio.

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: A system for encrypting and verifying a data packet includes an encryptor (20), a decryptor (30), an error detector (40), and switch (65). A data packet with embedded error detection codes is encrypted by the encryptor (20), decrypted by the decryptor (30), and then the error detector (40) examines the embedded error detection codes to determine if the data packet has had errors introduced during the encryption/decryption process. When errors are detected, the switch (65) is opened to keep erroneous data from being transmitted.

Abstract: A method and apparatus for rapidly characterizing a communications channel is used to mitigate the effects of the communications channel as present in a received signal. A satellite (20) transmits a data signal (40) and a pilot signal (50). The data signal (40) and the pilot signal (50) are substantially orthogonally polarized. A user terminal (30) receives the orthogonally polarized data signal (40) and pilot signal (50). The user terminal includes a channel information recovery circuit (250) and a channel effects mitigation circuit (240). The channel information recovery circuit (250) characterizes the communications channel by analyzing the pilot signal (50), and then provides the channel information (260) to the channel effects mitigation circuit (240) which then mitigates the effects of the channel.

Abstract: A method and apparatus for providing global message monitoring in a paging system includes a message origination and delivery device (MODD) (20). The MODD (20) includes a data structure (100) which identifies certain users as message monitoring users. Message monitoring users receive monitored page messages (300), which are duplicates of pages sent to users being monitored. The MODD (20) sends pages to a pager in the possession of the message monitoring user.

Abstract: A satellite (110 FIG. 1) is used to make channel allocations for SUs (120) in communications system (100). Satellite (110) operate within the confines of at least one subset of satellites. Satellites (110) allocate channels using a maximum cost list that is based on a cost function methodology. A list of potentially interfering antennas is determined using a cost function analysis. A list of active channels on each one the potentially interfering antennas is also established. Another list that includes a set of potentially interfering channels for each active channel is established. Cost functions are computed for each pair of active channels and its potentially interfering channels. These cost functions establish interference potentials for the available channels in the maximum cost list (400). Channels are allocated using the maximum cost list and interference potential thresholds. Cost functions are based on spatial isolation, spectral isolation, and temporal isolation.

Abstract: A system for encapsulating ATM cells into larger data packets to be transmitted through a broadband communications system includes an ATM cell receiver (410), a data packet formatter (430), a buffer (434), and a data packet formatter controller (438). The ATM cell receiver (410) receives ATM cells and sends them to the buffer (434) which is included within the data packet formatter (430). Data packet formatter controller (438) controls the insertion of ATM cells into the buffer (434), and also optionally compresses the ATM cells to increase the apparent bandwidth of the system.

Abstract: A phase domain multiplexed communication system generates N carrier frequencies each with a unique phase according to a selected orthogonal vector containing N elements. A subscriber information signal is first divided through a signal divider (215, FIG. 6). Each divided signal is then upconverted through a mixer (220) and phase shifted according to the selected orthogonal vector. The resulting signal is then combined through a summing element (250) and transmitted. At a receiver, the incoming signal is coupled to a signal divider (315, FIG. 7) where the signal is divided into N signal components. Each signal component is downconverted and phase shifted so that the transmitted subscriber information can be extracted at a summing element (350). At the summing element (350) the desired subscriber signal components add in-phase while the signal components corresponding to other subscribers add out-of-phase.

Abstract: A method and apparatus for providing location-based intercept in a system includes an intercept monitoring unit (210) for dynamically modifying an intercept target list (245) in a communications switch (240). The intercept monitoring unit (210) determines, as a function of user location, whether the user's call should be intercepted. If so, either an updated entry is made to the intercept target list (245), or an entire updated copy of the intercept target list (237) is downloaded to the communications switch (240).

Abstract: The testing and verification of CDMA cellular base stations requires a number of parameters to be measured. Many of these parameters are measured in the code domain where individual waveforms are extracted from a composite waveform through the use of orthogonal codes. A method and apparatus is described for measuring many code domain parameters using a modified code domain power measurement technique. The apparatus is comprised of a chip timing recovery circuit (46), a reference generator (78), a multiplier (60), various summers and absolute value operations, a memory (76), and a processor (90). In addition, a reference generator (78) for generating an improved reference waveform is described. Reference generator (78) is comprised of a Walsh code generator (200), an I channel PN sequence generator (202), a Q channel PN sequence generator (204), an XOR gate (206), and an XOR gate (208).

Abstract: A method for providing location based intercept in a satellite communications system (10) includes the steps of determining a location area of a party (220), determining whether the location area is one to be monitored (240), and conditionally routing the call to an intercept gateway (250). An intercept gateway (32) is a gateway that intercepts all or part of the calls received, and can also function as a home gateway (30) or a visiting gateway (40).

Abstract: A method and apparatus for centralizing the administration of intercept lists includes a master intercept list (305) and an interface (510) which communicates with switches (410). Switches (410) may or may not include local intercept lists (415). When a user makes a call, a switch (410) queries the local intercept list (415) or the master intercept list (305). Information from the query is used to determine whether to intercept the call.

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: 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.

Abstract: A method and apparatus for efficient power amplification over a wide dynamic range and for a number of modulation formats includes a carrier amplifier (30) and a peaking amplifier (40). The carrier amplifier (30) operates with a bias generated by an envelope amplifier (80) which amplifies the envelope of an input signal as generated by an envelope detector (70). The peaking amplifier (40) operates with a fixed bias. The outputs of the carrier amplifier (30) and the peaking amplifier (40) are combined using an impedance transforming network (50). Envelope amplifier (80) can be turned on for high efficiency low power level operation, or it can be turned off for standard Doherty-type operation.

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 method and apparatus for efficiently tracking satellites includes a geosynchronous satellite (10) for transmitting the ephemeris of non-geosynchronous satellites (20, 30) to a ground terminal (50). The ephemeris is computed by the non-geosynchronous satellites (20, 30) or by other means such as a ground station (60). A ground terminal (50) can quickly acquire a non-geosynchronous satellite (20, 30) by receiving fresh ephemeris data from a geosynchronous satellite (10), determining a location of a non-geosynchronous satellite (20, 30), and orienting an antenna.

Abstract: A packet data communication system (10) where multiple users (87) can access the same channel (22) to maximize an efficiency of the communication system (10). Each channel (22) is divided into time slots. Each time slot is allocated to a user based on the user's request (303) for time slots and the availability of time slots. If time slots are available, then the system (10) will inform the user (87) and allocate the time slot to the user (87, 305). If there are no available time slots, then the system (10) will inform the user (87) that no time slots are available and access to the system's channel is denied. The user (87) will continue to request access (303) to the system (10) as long as the user has data packets to send.