Abstract: A dual pattern antenna (FIG. 1, 20) functions as a bi-filar or quadrifilar helical antenna depending of the location of the feed element (FIG. 4, 120). When the feed element (120), within the hollow dielectric tube (FIG. 4, 140), is used to feed the antenna (20) at a distal end portion (FIG. 4, 142) the antenna functions as a bi-filar helical antenna and exhibits a relatively omnidirectional radiation pattern (FIG. 3, 70). When the feed element is used to feed the antenna at a proximal end portion (FIG. 4, 141), the antenna (20) functions as a quadrifilar helical antenna having a radiation pattern which exhibits desirable gain properties in the area above the antenna (FIG. 4, 40). The use of capacitive coupling allows the feed element (120) to slide within the hollow dielectric tube (140) so that the pattern of the antenna can be quickly changed, thus making the antenna well-suited for portable communications devices such as satellite cellular telephones.

Abstract: A radio frequency signal (FIG. 2, 205) is sampled and the sample is conveyed to a video detector (220). The detected envelope amplitude is sent to an envelope tracking circuit (280), a comparator (230), and an envelope tracking and gate biasing circuit (240). Based on the instantaneous value of the envelope amplitude, the comparator (230) selects one of the available supply voltages (340) via switch drivers (270). The selected one of the available supply voltages (340) is adjusted by the envelope tracking circuit (280) and the resulting voltage output (282) is supplied to the drains of the power amplifiers (390), thus enabling operation near saturation. As the instantaneous value of the envelope amplitude increases, the comparator (230) selects higher supply voltages (340) which increases the voltage conveyed to the power amplifiers (390), thereby increasing their power output.

Abstract: A method and apparatus for communicating between wireless communication devices (120, 131, 140) uses a high-altitude communication platform (110) to provide an interface between the devices. The platform (110) enables multiple signals from multiple sources to be combined into one signal which is sent to a ground device (120). The ground device (120) can send a combined signal to the platform (110) which the platform (110) can then separate and send to multiple destinations. The platform (110) can be used as a bridge between satellites (1310, 1312) which are incapable of direct communication, thus enabling a fully connected network to exist without full coverage from satellites.

Abstract: A temperature compensated resonator (15) and method for making the temperature compensated resonator (15). The temperature compensated resonator (15) has a substrate (110) including a cavity (120, 160) and a resonator layer (150). A bonding medium (159, 160) couples the substrate (110) to the resonator layer (150). The resonator layer (150) is bonded atop the cavity (120, 160). A conductor (215) is included on the resonator layer (150). The conductor (215) heats the resonator layer (150) in response to a current passing through the conductor (215).

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: A method and system for reducing the sampling rate of a signal for use with high modulation index frequency modulated signals reduces the power consumption and processing requirements of the digital signal processing equipment which performs the demodulation. In a preferred embodiment, a high modulation index FM signal is divided into in-phase and quadrature phase components by a downconverter (FIG. 1, 10). These components are sampled by analog to digital converters (20, 21) and input to a delay element (40, 41). The resulting delayed and undelayed samples are conveyed to downsamplers (60-63) where the sampling rate is reduced. The undelayed in-phase and delayed quadrature phase components are multiplied together by a first multiplier (70) while the undelayed quadrature phase and delayed in-phase components are multiplied together by a second multiplier (71).

Abstract: A dual quadrature branchline in-phase power combiner and power splitter provides a low cost and symmetrical structure for combining power from two signal ports (20, 30, FIG. 1) to an output signal port (10). When used as a power splitter, the structure accepts power from a signal port and divides the power equally and in-phase between the output signal ports (20, 30). The structure can be fabricated using microstrip, stripline, or similar technology such as suspended stripline. The structure is well matched over a large bandwidth and provides high isolation between the splitter output signal ports (20, 30).

Abstract: In a satellite communication system, a satellite (FIG. 1, 150) determines its position through the reception of global positioning system signals (180). The satellite (150) then broadcasts its position by way of a wide coverage antenna (152) transmitting a low data rate position broadcast (125). A ground station (110) receives the low data rate position broadcast (125) and directs a narrow beam antenna (120) to the reported position of the satellite (150). The ground station (110) then begins high data rate communications with the satellite (150) through the narrow beam antenna (120).

Abstract: A method for a radio frequency communication unit (110) (CU) to hand off from a losing node (120) to an alternate node (122) estimates one or more alternate node uplink times (240) and alternate node uplink frequencies (242), which the alternate node uplink signal comprises. During handoff, the CU (110) ceases communications with the losing node (120) and immediately begins communications with the alternate node (122) using the uplink time and uplink frequency. A CU apparatus (300) uses a processor (302) for carrying out calculations necessary for estimating the alternate node uplink time and frequency. Information necessary for the calculations, such as a downlink signal time-of-arrival and Doppler offset, are collected by a CU receiver (306). The CU receiver (306) and a CU transmitter (304) are used to support downlink signals (142) and uplink signals (140), respectively, between the CU (110) and a node (120, 122).

Abstract: In a satellite communication system, beamforming is performed at baseband frequencies forming only beams which convey information. A received signal is applied to a downconverter (FIG. 1, 30), followed by a channelizer (50), and digital beamformer (60). The order of operations being reversed in order to generate a transmit beam. By performing the beamforming at baseband, the system can be allowed to form only those beams which convey information between a communications node and a subscriber. As a result, the system provides communication services to subscribers in a more cost-effective manner.

Abstract: A battery powered electronic system (50, FIG. 1) is controlled by a movement sensor (20) which senses the acceleration of the electronic system (50). The output of the movement sensor (20) is filtered by an event duration filter (FIG. 2, 120, 121) which determines if the output is of sufficient duration and acceleration to trigger a change in the operation of the electronic system (50). If the acceleration meets the triggering criteria, the electronic system (50) can be made to change an on/off state, an operating mode, or to effect an incremental change in the electronic system (50) such as adjusting the volume or channel setting. Additional movement sensors (20) oriented in different axes can be used to trigger a change in the operation of the electronic system (50) according to a plurality of different directions of acceleration.