Abstract: This invention reduces the navigation error associated with the use of wheel sensor based DR as an augmentation to GPS. In order to derive accurate heading information from the wheel speeds, the distance between the centers of the tires, or the wheel track, must be known to high precision. Unfortunately, the wheel track may not be precisely known whereby different classes of the same vehicle type can produce variations of up to 5%. The current invention removes the error growth associated with wheel track error by automatically estimating and calibrating the wheel track. The wheel track is measured by computing a heading rate directly from the GPS Doppler measurements, and comparing it with the heading rate derived from the wheel sensors whereby subsequent refinements to the estimated wheel track are computed by filtering each measured track.

Abstract: The present invention describes a method and apparatus for improving the autocorrelation performance in spread spectrum radar and communications systems by using a tri-state digital correlator to demodulate the received biphase modulated waveform. The tri-state correlator (100) includes a multiplexer (112) having a code input for receiving a tri-state code sequence, and three inputs each for receiving a sequence of data words including a first input for receiving a digitized signal data word, a second input for receiving an inverted digitized signal data word, and a third input for receiving a zero data word. The multiplexer includes an output and a means for producing a sequence of data words at the output, said means presenting at the output exactly one of the three data words appearing at either the first, second, or third input depending on which of the three code states appears at the code input.

Abstract: An rf transmitter (319) used with a single cell battery (101) includes a voltage boost circuit (211) integral with a class S amplifier (290). An rf signal to be amplified is separated into its envelope (amplitude) and phase components. The phase component is applied to the input of a power amplifier (260). The envelope is applied to a pulse width modulator (275) which is used to modulate the voltage supplied to the power amplifier (260). The pulse width modulator (275) controls electronic switches (285, 286) which are disposed between the single cell battery (101) and the primary of a step up transformer (211). The secondary of the transformer (211) is coupled to supply voltage to the power amplifier (260). In this manner, the class S amplifier is powered directly from the single cell battery, via a the transformer (211), and power consumption is substantially reduced due to the switching operation of the switches (285, 286).

Abstract: A system for a pipeline cascaded content addressable memory CAM system for sequentially processing input data includes an input register, a CAM core, cascade logic and an output register. As the memory association functions produce matches in the CAM core, the cascade logic in parallel composites data associated with each matching CAM core. Each cascade processes a separate data input simultaneously then passes on the cumulative results to the next stage.

Abstract: A method and apparatus for the selection of random values from a set of N non-sequential values includes software in ROM and RAM for information pool storage. Coupled to the ROM and RAM, a microprocessor sorts the values from smallest to largest, initializes local variables, processes a current value from a first value of the set, and compares the difference to a current information pool entry difference. A range increment is incremented if the difference equals the current information pool entry difference and a new information pool entry is created if the difference does not. The information pool is stored and random values are selected by generating a pseudo random number, constraining the pseudo random number between one and N, indexing into the information pool using the pseudo random number to create a pool entry index and generating the random value using a selected pool entry first value.

Abstract: The present invention describes a communications system that utilizes frequency division multiple access (FDMA), code division multiple access (CDMA), and time division multiple access (TDMA) techniques for providing efficient use of frequency spectrum while supporting a large number of transmitters/users (2-6). Many users of the communications system share a common frequency band, but each transmit their respective message bursts (50) at different and specific times via a TDMA technique. To facilitate synchronization of the TDMA technique, each transmitter of the system is synchronized to a common timing reference (1) thereby abating the need to maintain synchronization between the transmitters (2-6) and receivers (8-12) of the system.

Abstract: A GPS based search and rescue system utilizes an airborne interrogation unit for extending the range of a second interrogation unit. The airborne unit relays communication between a survival radio and the second interrogation unit. The second interrogation unit is typically a ground based unit and is arranged to provide GPS correction information to the survival radio. The normal line of sight communication between a survival radio and an interrogation unit is extended to an over the horizon communication path by utilizing the airborne interrogation unit as a relay for communications.

Abstract: The present invention encompasses a method of storing ternary data that includes the steps of (1) initializing a conversion register by storing binary-to-ternary mask data in a conversion register; (2) storing ternary data in a content addressable memory (CAM) by inputting a single bit binary data to the conversion register, and converting the binary data into two bits of ternary data using the conversion register; and (3) simultaneously storing the two bits of ternary data in first and second memory cells. For subsequent searching, the method further includes the steps of searching for a match of input search binary data to the stored contents of the CAM; providing a match valid output responsive to the input search binary bits matching any of the stored contents; and generating an address corresponding to a location in the CAM where the match is found.

Abstract: Invalid transmissions in an ATM network (200) are identified by maintaining a user profile (304) relating to network use for each participating node of the network (200) and detecting potentially invalid transmissions based on a deviation (312) from the user profile. In a preferred embodiment, the user profile is continuously updated by monitoring transmissions within the ATM network (200), taking advantage of information included in defined fields of the transmitted ATM cells. When a detected deviation exceeds a predetermined threshold (314), the source node of the transmission is investigated to verify the identity of the source node user. The investigation is accomplished prior to establishing a security link between the source node and a secured node (202), thereby increasing availability of the secured node (202) for use by authorized network users.

Abstract: A cellular communication system (10) forms cells (18) from low earth orbit satellites (12). The system (10) uses an off-line process (24) to identify cells (18) that fall within various reuse distances of other cells (18) and to save system usage statistics. An on-line process (42) associates a demand with each cell (18), and the demand is predicted from the system usage statistics. Need factors assigned in response to the cells' demands are ranked and processed by an inner loop that assigns the various ones of the cells (18) to one channel (22) at a time and an outer loop that performs the inner loop for many different channels (22). The inner loop assigns cells (18) to a selected channel (22) in accordance with the need factor ranking.

Abstract: A method and apparatus for automatic tuning calibration of electronically tuned filters which comprises a programmable frequency generator for producing a calibration frequency signal, a filter for filtering the calibration frequency signal, a detector for producing a detector voltage, a processor for programming the frequency generator to specific test frequencies and for producing a stepped filter tuning voltage and storing the detector voltage in response to the stepped filter tuning voltage, and a converter for digital-to-analog conversion of the stepped filter tuning voltage. Calibration frequency signal versus tuning voltage responses are stored for a number of calibration iterations within the usable range of the filter and the resulting table can be used to determine the correct tuning voltage for the filter when operating at any frequency within the usable filter range.

Abstract: A system (10) includes any number of Boundary-Scan integrated circuits (28), a common bus (14), and a Boundary-Scan master (22). The integrated circuits (28) include mode selection logic (58) that isolates pins (30, 32) from core logic (34) during Capture-DR, Update-DR, Run-Test/Idle, and Select-DR-Scan states (66, 88, 62, 64) when a system action instruction is active so that a system action may be asserted. During all other states, including a Shift-DR state (82), the pins (30, 32) remain coupled to the core logic (34). The Boundary-Scan master (22) includes an arbitration interface (112). The arbitration interface (112) requests control of the common bus (14) prior to the time when the integrated circuits (28) assert a system action. The Boundary-Scan master arbitration interface (112) then releases control of the common bus after system action by the integrated circuits (28) is completed.

Abstract: This invention reduces the error growth associated with vehicle Dead Reckoning (DR) systems utilizing heading rate sensors (15) by compensating for the lever arm or offset between the Global Positioning System (GPS) antenna (11) and the center of rotation of the vehicle. When turning at moderate speeds, the error induced in the GPS heading by this lever arm can be the dominant error effect. Accordingly, the present invention recognizes this source of error and further describes a method and apparatus for estimating and compensating for the error effect of this lever arm.

Abstract: A smart card (50) transfers information between the smart card and an external system (24) while having the capability of being accessed by a user. The smart card includes a microprocessing unit (MPU) (18) for executing instructions stored in memory, a display (28), coupled to the MPU, for displaying information, a keypad (26), coupled to the MPU and to the display, for entering data by the user, an interface (54,56) for transferring signals between smart card and the external system when the smart card is coupled to the external system, and photovoltaic cells (52) for providing power to the smart card when the smart card is exposed to light. The smart card does not require the use of a bulky and inflexible battery and since the solar cells used are flexible, the flexibility of the smart card is maintained.

Abstract: A memory linked address generator and method for a complex arithmetic processor executing an algorithm sequence includes memories, a clock for generating a clock cycle, and a decoder for determining position of the complex arithmetic processor within the algorithm sequence. The decoder is coupled to the clock and address pointer generators are coupled to the decoder and to the memories. The address pointer generators generate address pointers within the clock cycle for at least some of the memories in response to the position of the complex arithmetic processor within the algorithm sequence.

Abstract: A method for processing patent text (99) in a computer (200) including identifying boundaries of parts of patent text (100), loading at least one of the parts of the patent text into a working memory (102), analyzing at least one of the parts of the patent text (104), and reporting results (106) to a user (202). Alphanumeric drawing data can also be compared to patent text (100). The method can be coupled to work with a word processor program (208). The method can recognize and report (106 and 708) on claim dependency (400, 402, 404), specific characteristics (704) of patent text (99), and patent errors based on legal standards, practice standards, and Patent and Trademark Office standards, or even user preferences (702, 704, 706).

Abstract: In a Global Positioning System (GPS) receiver, a significant improvement in the detection of GPS data in the presence of high interference levels is provided. In the receiver, data from multiple frames of GPS data are stacked in a memory. The stacked data is then utilized to determine the GPS data.