Abstract: An earthmoving machine including a control system is disclosed. The machine comprises first and second satellite navigation antennas mounted in a longitudinal direction on the earthmoving machine. A third satellite navigation antenna is mounted on a pole attached to an operational element of the earthmoving machine. In one embodiment, the earthmoving machine is a bulldozer and the operational element is a blade of the bulldozer. The machine further comprises a gravity reference sensor and a plurality of gyroscopes mounted on the machine. A computer processor generates control signals based on sensor data received from the various components. The disclosed system and method allows for dynamically stable operation of the earthmoving machine at relatively fast speeds without the development of unwanted oscillations.

Abstract: A method and apparatus for estimating the changing frequency of a signal received by a satellite receiver from, illustratively, positioning system satellites is disclosed that enables a more accurate measurement of the change in frequency of that signal due to movement of the satellite receiver relative to those satellites. The system includes a PLL having a numerically controlled oscillator (NCO) and a filter of frequency estimates (FFE). In operation, an analog signal is received at the satellite receiver and the PLL tracks the changing signal frequency and outputs non-smoothed frequency estimates into the FFE. The FFE then smoothes noise in the signal to produce a more accurate smoothed frequency estimate of the input signal. Comparing multiple estimates over time allows Doppler shift of the signal frequency received by the satellite receiver to be calculated more precisely, thus resulting in more accurate satellite receiver velocity vector determinations and, hence, position measurements.

Abstract: A method and apparatus for resolving floating point and integer ambiguities in a satellite position navigation system is disclosed. A rover station is periodically positioned at unknown locations and has a satellite receiver capable of receiving the navigation signals. By calculating relative position coordinates between a base station in a known location and the rover station, and by calculating other position parameters relative to the satellite position, a geometric constraint based on a measured elevation angle between the rover and base station can be incorporated into data computations and processing to help resolve carrier phase ambiguities. The elevation angle is measured by transmitting multiple laser beams to an optical sensor on the rover station. This technique results in greater precision in determining the location of the rover.

Abstract: The invention relates to a method for enhancing an object-oriented programming language. The method includes declaring one or more class structures in databases having metadata describing characteristics defining the class structures. The method also includes extending the metadata associated with the class structures by adding any number of additional metadata to the databases.

Abstract: A satellite positioning device is disclosed for determining position based on received satellite navigation signals and a received non-satellite signal. A local clock controls the epoch period of a satellite signal processor. Correction signals are applied to the local clock in order to improve the synchronization between the satellite signal processor and the non-satellite signal processor.

Abstract: Disclosed is a method and apparatus for reducing inbound interference in a broadband powerline communication system. Data modulated on first and second carrier frequencies is received via respective first and second lines of the powerline system. A characteristic of at least one of the carrier signals (e.g., phase or amplitude) is adjusted at the receiver in order to reduce the effects of inbound interference on the transmission system. The adjustment parameters may be determined by adjusting the parameters, during a period of no data transmission, until the output of a differential receiver is zero.

Abstract: Secure communication protocols are disclosed in which two parties generate a shared secret which may be used as a secure session key for communication between the parties. The protocols are based on Diffie-Hellman type key exchange in which a Diffie-Hellman value is combined with a function of at least a password using the group operation such that the Diffie-Hellman value may be extracted by the other party using the inverse group operation and knowledge of the password. In one embodiment, each of the parties explicitly authenticates the other party, while in another embodiment, the parties utilize implicit authentication relying on the generation of an appropriate secret session key to provide the implicit authentication. Typically, the parties will be a client computer and a server computer.

Abstract: A method and apparatus for resolving floating point and integer ambiguities in a satellite position navigation system is disclosed. A rover station is periodically positioned at unknown locations and has a satellite receiver capable of receiving the navigation signals. By calculating relative position coordinates between a base station in a known location and the rover station, and by calculating other position parameters relative to the satellite position, a geometric constraint based on a measured elevation angle between the rover and base station can be incorporated into data computations and processing to help resolve carrier phase ambiguities. The elevation angle is measured by transmitting multiple laser beams to an optical sensor on the rover station. This technique results in greater precision in determining the location of the rover.

Abstract: Wireless devices within an ad-hoc wireless network adaptively set their transmission power levels based on locally available information. Initially, each such wireless device sets its transmission power level to a relatively low level, and gradually increases its power level up to a predetermined maximum transmission power level. As the transmission power increases, the wireless device is able to incrementally connect with additional wireless devices located at increasing distances from the wireless device. As the wireless device connects with these additional wireless devices, it checks a connectivity constraint. When the connectivity constraint is satisfied, the wireless device stops increasing its power and operates at its current power level. In one embodiment, the connectivity constraint is a geometric connectivity constraint based on the angular distribution of wireless device connections.

Abstract: Disclosed is a method and apparatus for multipath mitigation using an antenna array. An antenna array made up of a plurality of antennas is used to receive satellite signals from satellites. Various configurations of antenna arrays is disclosed, including a linear vertical antenna array and a horizontal antenna array in which the antenna elements are located in a horizontal plane. A switch sequentially connects each of the antenna outputs to a single processing path to generate a common additive signal. The common additive signal is provided to satellite channel processors, each of which processes the signals from an associated satellite. A phase shift correction signal associated with each of the antennas is generated and synchronously applied to a carrier phase reference signal. A blocking signal may be applied to the satellite channel processors in order to block the processing of signals from an unwanted satellite.

Abstract: A method and apparatus for detecting and correcting anomalous measurements in a satellite navigation receiver is disclosed. Anomalous measurements are detected using the redundancy of observed satellite signals, or by analyzing the relationship between phase measurements at two frequencies when using dual frequency receivers. Upon determination that an anomalous measurement exists, the particular channel on which the anomalous measurement has occurred is determined. In addition, the extent of the anomalous measurement is estimated to produce an estimated error value. This information may then be used by the satellite navigation receiver in order to increase the accuracy of a navigation task.

Abstract: Duplicate processing at network operators is avoided by applying once-only processing at operators which are adjacent to either the source or destination host of a data packet. An operator is adjacent to a host if there exists a path between the operator and the host containing no other operators. In one embodiment, an operator determines that it is adjacent to a host if it receives a special broadcast data packet from the host. To ensure that no other operators receive the special broadcast data packet, the adjacent operator drops the packet. In another embodiment, operators determine whether they are adjacent to identified hosts by transmitting special ping packets to the hosts. If an operator receives a ping response from the host, the operator determines that it is adjacent to the host. To ensure that only adjacent operators receive ping responses, intervening operators drop special ping packets received from other operators.

Abstract: A network server stores database tables for use in resolving labels into network addresses as requested by a remote browser client. Each user has an associated address-table which stores user defined labels associated with network addresses. Users may access other user's address-tables if such other users grant authority to do so. Each user defines the address-tables to be searched, along with a search order, to be used when the user requests that a label be resolved into a network address. During address resolution, the server will resolve a received label into the network address associated with the label as defined by the first accessed address-table which contains the label. The search order as defined by the user may be overridden for a particular address resolution request by an appropriate user command. In various embodiment, the network addresses may be WWW addresses and electronic mail addresses.

Abstract: Signal points from a PCM-derived constellation are selected for transmission via a modulation technique which employs different levels of redundancy coding—including the possibility of no redundancy coding—for respective different sub-constellations of the overall PCM-derived constellation. The coding that is employed for at least one of the sub-constellations is carried out independently from any coding that is employed for any of the other sub-constellations. The PCM-derived constellation and the overall modulation technique are designed so as to accommodate the possibility that the telecommunications system in which the modulation technique is implemented may include so-called bit robbing and so-called digital attenuation.

Abstract: A packet data filter which stores ordered rules and sequentially applies the rules to received data packets to determine the disposition of the data packet. The packet filter maintains a match count in memory which indicates the number of times each rule matched an incoming data packet. Periodically, at the initiation of a user, or based on operating parameters of the filter, the rules are automatically re-ordered based on the match count. As a result of the re-ordering, rules with higher match counts are moved earlier in the sequential evaluation order and rules with lower match counts are moved later in the sequential evaluation order. As such, rules which are more likely to match incoming data packets are evaluated earlier, thus avoiding the evaluation of later rules. In order to prevent a re-ordering which would change the overall security policy of the packet filter, pairs of rules are compared to determine if they conflict (i.e.

Abstract: A computer operating system in which transfer of control of executing threads between protection domains is implemented using specific portals dedicated to the particular transfer of control between two protection domains. The transfer of control may also include parameter manipulation. A server registers a portal specification with a portal manager, the portal specification defining the behavior of portals which transfer control to the server. Thereafter, when a client application desires service from the server, the client application requests instantiation of a portal which will transfer control of an execution thread from the client application protection domain to the server protection domain. Upon receipt of the request, the portal manager dynamically generates portal code and updates a portal table associated with the client application, thus instantiating the portal.

Abstract: A wireless terminal dynamically maintains location dependent operating parameters while operating in low power-consuming sleep mode. The wireless terminal wakes up periodically to determine its current location. If the current location is within a predetermined distance from a previously stored location, then the wireless terminal stores the previously stored location, along with its associated location dependent operating parameter, in a predetermined memory location within the wireless terminal. If the current location is not within a predetermined distance from a previously stored location, then the wireless terminal generates a new location dependent operating parameter for its current location and stores the current location and new location dependent operating parameter in the predetermined memory location. In various embodiments, the location dependent operating parameter may be, for example, a digital control channel or a mobile switching center identification.

Abstract: Two or more digital signals are encoded using two or more respective line codes. The line codes are chosen in conjunction with the data rates of the digital signals such that the encoded signals are substantially orthogonal to each other in the frequency domain. As such, the two or more encoded signals may be combined and transmitted via a single physical medium with little or no interference. A transmitter for encoding and transmitting the digital signals contains line coders for encoding the digital signals and a combiner for combining the encoded signals for transmission via a single physical medium.

Abstract: A contention-based network which allows real-time traffic to exist as multiple independent linked-list chains or under certain conditions to be assembled into multiple linked-list chains. A time separation is enforced between the various multiple chains, which are limited to a predetermined maximum number of stations that each can have in order to allow non-real-time stations to obtain timely access to the medium. Ones of the multiple chains may also be joined into a single chain. Blackburst contention is used to enable a chain to be reconstituted robustly from non-anticipated interruptions, such as the failure of one of its stations.

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The interleaver uses as its interleaved elements the bits associated with a particular symbol interval. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency.