Abstract: Systems and methods for passively calibrating and correcting for I/Q mismatch in a quadrature receiver without the necessity of modifying the analog portion of the receiver by adding calibration signals or correction circuitry are presented. The passive I/Q mismatch calibration system proceeds using normally received incoming transmitted data signals to obtain statistical information on which to base I/Q mismatch compensation factors. The I/Q mismatch compensation factors can be used to adjust the magnitude and phase response in the time domain or the frequency domain, the analog or the digital portion of the receiver. Depending on the embodiment, the passive I/Q mismatch calibration system can calibrate frequency dependent gain or magnitude imbalance, frequency independent magnitude imbalance, frequency dependent phase imbalance, and frequency independent phase imbalance or combinations or these.

Abstract: A method for determining the parameters and characteristics of an n-port network such as an amplifier is described. The parameters are determined by applying an input signal train or sequence with different amplitudes and measuring an output signal train, taking into account a temporal displacement that the output signal train has in relation to the input signal train. The temporal displacement is determined by a cross-correlation of the output signal train with the input signal train.

Abstract: A quadrature multi-frequency ranging system applied to DSSS multipath mitigation problems is described. The QMFR techniques include taking the time-of-arrival measurements on the received signal at a time when the multipath component is at a 90 degree angle to the direct path. Further, the preferred embodiment of the present invention recognizes that when a signal is transmitted at a series of frequencies, and the spread of these frequencies is sufficient, a quadrature or near quadrature condition can be forced to occur, at which the TOA estimation gives the highest certainty of measurement.

Abstract: A method and apparatus for automated correlation of digital modulation impairment is described. The technique obtains soft decision data (116, 2502) and extracts signal space location information of sufficient resolution to distinguish different types of impairment to a digitally modulated signal. The technique applies an error vector magnitude mask (117, 502) and determines the signal-to-noise ratio of the digitally modulated signal. The technique applies impairment masks (118, 2504) and provides a characterization (119) of impairment affecting the digitally modulated signal (112). The technique determines a subset of the soft decision data (116, 2502) that falls within the impairment masks (118, 2505) and calculates correlation weights (2506). The technique may be used to identify, isolate, and classify different types of impairment. Given sufficient data collection, sources of impairments may be determined precisely.

Abstract: A method for performing synchronization operations of a receiver to a received code-modulated spread spectrum signal whereby at least one reference code (r(x))is used. This reference code corresponds to a code used in the modulation. The frequency shift of the received signal and the code phase of the code used in the modulation are determined in the method. Hartley transformers are also used.

Abstract: The present invention provides a method and system for preprocessing transmit signals in spatial multiplexing and diversity systems that include multiple transmit antennae. The method includes generating a representative correlation matrix based upon estimates of a correlation between each pair of the plurality of antennae. An equivalent eigenvalue decomposition of the representative correlation matrix is determined. A preprocessing matrix based upon the equivalent eigenvalue decomposition is generated. Finally, a preprocessor preprocesses the transmit signals by multiplying blocks of data of the transmit signals with the preprocessing matrix. The representative correlation matrix can be an exact estimate of the correlation between each pair of the multiple antennae, or the representative correlation matrix can be an approximate estimate of the correlation between each pair of the multiple antennae.

Abstract: In a digital IF downconversion circuit, in-phase and quadrature signal components are processed in the form of a single serial digital bit stream through a set of simple logic in combination with a reconstruction filter. A source digital oscillator supplying digital signal mixers employs an oversampled digital word of four bits in length, all of which are binary weighted, to achieve at least sixteen levels of accuracy for a sine wave mixing signal without significant phase or amplitude error. The mixer mixes the digitized serial bit stream according to the clock with output of a four-bit wide table representing the source oscillator and the in-phase and quadrature signals are recombined digitally, followed by binary weighting using weighted resistors coupled into a filter. Thus, image rejection is a digital function which is unaffected by resistor tolerance.

Abstract: A received path timing detecting circuit in a receiver used in a DS-CDMA system, which can detect received path timing in multi path propagation channels even under surroundings in which noise and interference electric power are very large, is provided.

Abstract: A non-uniform filter bank is created by joining sections of oversampled uniform filter bands that are based on complex exponential modulation (as opposed to cosine modulation). Each filter bank handles a given, non-overlapping frequency band. The bands are not of uniform bandwidth, and the filters of different banks have different bandwidths. The frequency bands of the different filter banks cover the frequency of interest with gaps in the neighborhoods of the filter band edges. A set of transition filters fills those gaps.

Abstract: A communication system for a computer includes apparatuses and methods for providing commands and data between a host computer and a multi-channel modem via a single host-to-modem physical channel using multiple logical channels. The communication system suitably includes a logical channel upon which each modem receives command data. Signals asserted on the logical channel corresponding to commands for a particular physical channel are automatically treated as commands. Signals on noncommand logical channels are processed as data to be transferred. Consequently, each physical channel of the modem may be controlled without requiring an escape sequence.

Abstract: A method of operating a modem generally comprising the steps of (A) transmitting an invalid signal from the modem at each of a plurality of settings for an echo cancelling hybrid of the modem, (B) calculating a plurality of merit values each in response to an echo signal received by the modem in response to the invalid signal, and (C) adjusting the echo cancelling hybrid to a particular setting of the settings determined from the merit values.

Abstract: A data/clock recovery circuit can recover high-rate data using the data as a clock signal. It includes an edge detector, a clock selection signal generating circuit, a clock selection circuit and a synchronizing circuit. The edge detector generates edge position information using a receiver output as a clock signal. The clock selection signal generating circuit generates a clock selection signal in response to the edge position information using the receiver output as the clock signal. The clock selection circuit selects a recovered clock signal from a clock signal group in response to the clock selection signal. The synchronizing circuit synchronizes the receiver output using the recovered clock signal, and outputs it as a synchronized data signal.

Abstract: A frequency plan is provided for particular use in a transceiver. Advantageously, a single oscillator may be used to generate desired frequency signals. One or more power splitters receive the signal and equally divide the signal into first and second signals having a frequency substantially equal to the original. Multipliers on each arm of the transceiver receive a signal and increase the frequency of the signal. In one exemplary embodiment, multiple signals having different frequencies may be transmitted over the same cable due in part to the generated frequency separation between the signals. In another exemplary embodiment, multiple signals may be transmitted over multiple cables. Additionally, multiple signals over one or more cables may be transmitted at or below 3 GHz.

Abstract: The invention generally provides a method of intelligent frequency hopping such as in Bluetooth and Home RF networks. The method (400) includes the acts of generating windows (410), sampling an original frequency (430), determining if the original frequency is of a desired frequency type (440), using the original frequency when the original frequency is the desired frequency type (460), and mapping the frequency to the desired frequency type when the original frequency is not the desired frequency type (450). Accordingly, the method increases the reliability and throughput of wireless networks.

Abstract: A canceling method and apparatus can achieve a fast communication by improving an S/N value by adaptively canceling a noise with respect to a frequency or band having a large noise by selecting noise canceling band in accordance with a condition of noise being generated. A reception signal contains a specific signal having a specified time position, amplitude and phase. A noise distribution of the specific signal is recognized so as to predict a noise by extracting a frequency band having a larger noise component from a pair of frequencies generated by the insertion of the specific signal. An original transmission signal is reproduced by canceling the predicted noise from the reception signal.

Abstract: A method and apparatus for performing bandedge equalization. Specifically, the apparatus contains a pre-equalizer for adjusting the amplitudes of the bandedges of a broadband signal in response to a control signal. A bandedge filter is connected to the pre-equalizer and extracts a bandedge signal from the broadband signal. Lastly, a bandedge signal processor that is connected to the bandedge filter generates the control signal in response to said bandedge signal. In this manner, when the bandedges of the broadband signal are asymmetric, the apparatus adjusts the signal strength of each bandedge with respect to one another to equalize (balance) the bandedges. The balanced signal can then be used by a bandedge timing recovery circuit. As such, the accuracy of a bandedge timing recovery circuit is not impacted by the asymmetric bandedges of the input signal.

Abstract: Apparatus and methods for providing Rendezvous point Interpiconet Scheduling (RIPS) in an ad hoc polling based communication infrastructure such as a Bluetooth system in which a PMP node (Participant in Multiple Piconet nodes) belongs to more than one piconet. The rendezvous (RV) points of a PMP node is defined based on information specific to the node, rather than being associated with the links between slave and master nodes. By defining RV points per PMP node rather than per link, the master node of a piconet in the RIPS system is aware of the RV points that its slave PMP nodes have in other piconets. This advantageously allows a master node in the RIPS system to know when its slave nodes will be present in the piconet and when they will not be present.

Abstract: A novel and improved method for performing paging is described. In one embodiment of the invention a searcher is used to detect spread spectrum signals. Samples received RF signals are stored in a sample buffer. During standby mode, the samples are gathered during paging slots assigned to the mobile. A set of searches are performed on the samples, and if pilot signals are detected additional demodulation is performed to detect paging messages. The resulting set of demodulation data may be combined to increase detection. After a page message has been detected, additional demodulation resources may be activated to processes more complete page messages, or other information channels. In one embodiment of the invention, the searcher includes a demodulator to perform quick page detection without the use of finger elements to reduce idle mode power consumption.

Abstract: The present invention provides a method for encoding messages. The method includes identifying at least a first plurality of messages indicative of a corresponding first plurality of data transmission rates and a second plurality of messages indicative of a corresponding second plurality of data transmission rates based on a prior transmitted message, where the first and second pluralities of messages are unequal. The method also includes transmitting a message from one of at least the first and second pluralities of messages.

Abstract: Methods and systems for communication systems are disclosed. Chirp signals generated according to a chirp rate and carrier frequency are used for communication. The chirp rate can be determined by solving integrals or by simulation of transmission parameters. A chirp signal is transmitted from a base station and delayed versions of the chirp signals are created. The delayed versions are generated by the chirp signal reflecting off of reflectors. A receiving station receives an incoming signal. The incoming signal includes the LOS signal plus delayed versions, noise and/or interference. Unwanted signals, either LOS or delayed versions, noise and/or interference are removed from the incoming signal to obtain the desired chirp signal. Using the chirp rate, the chirp signal is converted to a corresponding digital signal.