Abstract: An improved antenna diversity system is provided. The antenna diversity system has at least two spaced-apart antennas, with each antenna providing a respective antenna signal. The signal(s) may be processed and scaled according to its respective power level. The phase difference is determined between the signals, and the phase difference reduced by using phase rotation. The signals, which are now substantially in-phase, are summed to generate a combined antenna signal.

Abstract: A complex signal in which one of two signals that are generated from one real signal and that have phases shifted from each other by 90° is a real part and the other signal is an imaginary part is applied as input to an input terminal. A filter unit generates an output signal that is a complex signal by means of a convolution operation of this input signal and filter coefficients that are real signals and supplies the result to an output terminal. A coefficient control unit composed of a common unit and separate units controls the envelope target value based on the input signal and updates the filter coefficients such that the value of the envelope derived from the output signal approaches the envelope target value.

Abstract: A wireless receiver having improved receiving characteristics is provided.

Abstract: A redundancy system for a co-channel telecommunication system and related methods. Implementations of the redundancy system may include at least a first modulator and a second modulator having a symbol mapper coupled to a parallel bit signal. The symbol mapper may be configured to route each of a plurality of parallel bits received through the parallel bit signal to a plurality of significant bit signals. In a first implementation, a plurality of significant bit signal multiplexers may be used to switch the plurality of parallel bit signals to allow the first and second modulators to operate in either a redundant or operating mode. In a second implementation, a premapped symbol (PMSI) encoder and a PMSI decoder may be used to transmit the plurality of significant bit signals across an interface bus as a real dual-data rate (DDR) signal and an imaginary DDR signal.

Abstract: A demodulation section 13 receives a TDMA-TDD based phase-modulated burst signal of mobile communications and demodulates the burst signal by a synchronous detection system (or a quasi-synchronous detection system). The demodulation section 13 includes a frequency deviation compensation section and a carrier recovery section each having a loop filter 14 with three or more stages of time constants. The time constants are switched by a selector switch 15 based on a control signal from a demodulation control section 16. This achieves quick pull-in and jitter after convergence is minimized, thereby allowing highly efficient performance of frequency deviation compensation, etc. that is required for synchronous detection (or quasi-synchronous detection) without increasing the size of circuit.

Abstract: In one embodiment, the present invention includes a mixer circuit to receive and generate a mixed signal from a radio frequency (RF) signal and a master clock signal, a switch stage coupled to an output of the mixer circuit to rotatingly switch the mixed signal to multiple gain stages coupled to the switch stage, and a combiner to combine an output of the gain stages.

Abstract: Systems and methods that reduce phase noise are provided. In one embodiment, a method may include one or more of the following: generating a signal at a particular frequency in which the signal may be associated with a harmonic frequency signal disposed at a harmonic frequency; and selectively attenuating frequency content disposed in a region around the harmonic frequency. The signal may be associated with a second harmonic frequency signal disposed at a second harmonic frequency. Frequency content disposed in a second region around the second harmonic frequency may be selectively attenuated. One or more non-linear operations may be applied to the signal and the applied signal may be transmitted.

Abstract: A frequency phase correction system and method are described that provides a receiver with a greater ability to lock onto relatively weak radio frequency signals by determining and estimating an amount of frequency error in a local frequency reference of the receiver, and using the error estimate to maintain frequency coherence with a received signal, thereby allowing tracking over a longer period of time, enabling longer integration times to capture weaker signals without losing frequency coherence.

Abstract: Methods and systems for wireless communication are disclosed and may include band-limiting a wireless signal utilizing a programmable bandpass filter, generating a first signal by undersampling utilizing a clock signal and generating a second signal by undersampling the signal utilizing a delayed version of the clock signal, which may then be subtracted from the first signal. The filter may comprise a microstrip or a coplanar waveguide bandpass filter. The delay may be variable, and may be defined as an inverse of a frequency difference between the desired channel and a blocker signal. The bandwidth of the filter may be centered at the desired channel. The clock signal may be generated at a frequency which may be an integer sub-harmonic of the desired channel, and may be greater than twice a bandwidth of the filter. The delay may be controlled by a programmable delay circuit, which may comprise CMOS inverters.

Abstract: An apparatus and method for controlling amount of information to be fed back in a multiple antenna system in a multi-user environment. The apparatus includes a channel estimator which estimates channel values by using an input signal; a Singular Value Decomposition (SVD) operator which decomposes singular values from the estimated channel values; and a feedback determining unit which uses the singular values to compute channel capacity that can be obtained according to the amount of channel information to be fed back, and selects the channel information to be fed back by using the channel capacity.

Abstract: Methods and systems for a local oscillator generator based on quadrature mixing using a phase shifter. Aspects of one method may include generating a local oscillator signal, where a frequency of the local oscillator signal may be determined by controlling a phase of in-phase (I) components and quadrature phase (Q) components of a first signal and a second signal. For example, by appropriately controlling a phase of each component that is to be mixed, the local oscillator signal may have a frequency that is the sum of a frequency of the first signal and a frequency of the second signal, or a difference of the frequency of the first signal and the frequency of the second signal.

Abstract: A mobile radio frequency identification (mRFID) reader having a receiving circuit is provided. The receiving circuit includes a local oscillator which generates a carrier signal at a predetermined frequency band; a mixer which mixes a tag signal received from a tag with the carrier signal, to lower a frequency of the tag signal; a phase adjusting block which adjusts a phase of the carrier signal by determining a phase of the tag signal; and a control block which processes the tag signal through a series of operations, and controls an operation of the phase adjusting block to compensate for a phase delay of the tag signal according to an output of the processed tag signal. Because the mRFID reader can be provided as small as a half size of a related art reader, a mobile communication terminal accommodating the mRFID reader can be compact-sized. Additionally, because the number of components for the receiving circuit decreases, not only the power consumption but also the unit price can be reduced.

Abstract: Complex antennas weights for use in beamforming in a multiple-antenna system are determined based upon clear channel assessment (CCA) information in a wireless networking environment.

Abstract: A radio system having an improved phase noise characteristic and a thereby improved communication quality, a radio transmitter, and a radio receiver. In the radio system, a radio transmitter (101) transmits a multiplexed signal so multiplexed that a pilot signal transmitted at the center frequency.

Abstract: Systems and methods are presented for digital antenna diversity combining. In exemplary embodiments of the present invention, at least two antenna signal paths can be communicably connected to a receiver. Each antenna signal path can be provided with an RF tuner communicably connected to a demodulator, which can estimate the signal to noise ratio (SNR) and time of arrival of its respective antenna signal. In exemplary embodiments of the present invention, a time alignment circuit can be communicably connected to each antenna signal path, and a maximum ratio combiner can be communicably connected to the time alignment circuit. In operation, the time alignment circuit can use the time of arrival estimate to align the multiple signals and the maximum ratio combiner can use the SNR estimate obtained for each antenna signal to respectively weight each signal and thereby generate a combined output signal.

Abstract: A plurality of music apparatus 10 to 30 such as an electronic musical instrument and a microphone apparatus are connected by wireless to a mixer apparatus 40. A Bluetooth module is adopted as wireless communication means to construct a piconet with mixer apparatus 40 functioning as a master and music apparatus 10 to 30 functioning as slaves. Audio signals and MIDI data from music apparatus 10 to 30 are transmitted by wireless to mixer apparatus 40 through isosynchronous communication procedure using Bluetooth modules 11, 21, 31, 41. In mixer apparatus 40, with regard to the MIDI data, music tone signals based on the MIDI data are produced, whereafter the produced music tone signals and the aforesaid audio signals transmitted by wireless are mixed. Wiring by means of cables between a plurality of music apparatus and a mixer apparatus is abolished, thereby eliminating the cumbersomeness of wiring and the restrictions accompanying the wiring.

Abstract: A near field microwave scanning system includes a switched array of antenna elements forming an array surface, a scan surface substantially parallel to the array surface and separated by a distance less than about 1 wavelength of the measured frequency, and a processing engine for obtaining and processing near field data, without the use of an absorber.

Abstract: A downconverter and upconverter are provided which can obtain a sufficient image rejection ratio in a low-Intermediate Frequency (IF) scheme while reducing power consumption and can suppress Error Vector Magnitude (EVM)-related degradation in a zero-IF scheme. A complex-coefficient transversal filter rejects one side of a positive or negative frequency, and converts a Radio Frequency (RF) signal to a complex RF signal configured by real and imaginary parts. A local oscillator outputs a real local signal with a set frequency. A half-complex mixer, connected to the complex-coefficient transversal filter and the local oscillator, performs a frequency conversion process by multiplying the complex RF signal output from the complex-coefficient transversal filter and the real local signal output from the local oscillator, and outputs a complex signal of a frequency separated by the set frequency from a frequency of the RF signal.

Abstract: Calculating a phase adjustment includes establishing a current phase adjustment for a signal transmitted from a modifying communication device to a feedback communication device. A control signal is received. The control signal comprises windows communicating power indicators that reflect the power of the signal. A previous window communicates power indicators reflecting the power of the signal, and a current window communicates current power indicators reflecting the power of the signal. A previous power trend is estimated from previous power indicators, and a current power trend is estimated from current power indicators. A power trend change is determined from the previous power trend and the current power trend, and a phase increment is determined in accordance with the power trend change. A next phase adjustment is calculated from the current phase adjustment and the phase increment.

Abstract: Improved apparatus for a radio communication network having mobile transceiver units in communication with base transceiver units. The radio communication network is adaptive in that in order to compensate for the wide range of operating conditions, a set of variable network parameters are adapted for communication between transceivers in the network. These parameters may, for example, define optimized communication on the network under current network conditions. Examples of such parameters may include, without limitation: data rate, type of modulation, type or degree of error correction coding, packet length and spread spectrum communication parameters.

Abstract: A television tuner that receives a television signal using a smart antenna includes a rescan unit that executes rescan; that is: that when an instruction that instructs direct selection of a reception channel on which a television signal is currently received is issued during reception of a television broadcast service, causes an antenna control section to vary or control the receiving direction of the smart antenna and causes a signal state detector section to detect the states of signals sampled in all receiving directions; and that if the state of a signal detected by the signal state detector section agrees with a predetermined signal state, preserves the receiving direction of the smart antenna in which the signal is sampled. Consequently, rescan can be executed for all the receiving directions of the smart antenna by performing a simple manipulation.

Abstract: A communication system is presented. The system includes one or more transmitters configured to transmit a signal, where each of the signals generated by the one or more transmitters corresponds to a respective frequency. Further, the system includes a plurality of receiver front-ends configured to receive the signal transmitted by each of the one or more transmitters. The system also includes a plurality of remodulator modules configured to translate each of the received signals to a signal having a respective intermediate frequency. In addition, the system includes a combining module configured to combine each of the signals having respective intermediate frequencies to generate a single composite signal. Also, the system includes a single analog-to-digital converter configured to process the composite signal and generate a digital output. Additionally, the system includes a digital signal processor module configured to extract the signal transmitted by each of the one or more transmitters.

Abstract: In a wireless transmitting device which performs transmission by an OFDM using a plurality of subcarriers orthogonal to each other, a plurality of preambles to which a plurality of different subcarrier groups selected from a plurality of subcarriers within an OFDM signal band are allocated are transmitted by using a plurality of transmit antennas, and data is transmitted by using the antennas after the preambles are transmitted.

Abstract: A configurable all-digital coherent demodulator system for spread spectrum digital communications is disclosed herein. The demodulator system includes an extended and long code demodulator (ELCD) coupled to a traffic channel demodulator (TCD) and a parameter estimator (PE). The demodulator also includes a pilot assisted correction device (PACD) that is coupled to the PE and the TCD. The ELCD provides a code-demodulated signal to the TCD and the PE. In turn, the TCD provides a demodulated output data signal to the PE. The PACD corrects the phase error of the demodulated output data based on an error estimate that is fed forward from the PE. Accumulation operations in the ELCD, TCD, and PE are all programmable. Similarly, a phase delay in the PACD is also programmable to provide synchronization with the error estimate from the PE.

Abstract: A radio broadcast receiver is provided which reduces the degradation in quality of diversity-received signals. When a difference in level between a reception signal of a main antenna and a reception signal of a sub antenna is less than a predetermined threshold value, and when a difference in phase between the reception signal of the main antenna and the reception signal of the sub antenna exceeds another predetermined threshold value, a combination ratio of a combiner for combining outputs of a main tuner and of a sub tuner is set to 1:1, where in-phase combination type diversity is carried out. In other cases, the combination ratio of the combiner is switched between 1:0 and 0:1 depending on the occurrence of a multipath, where selection diversity is carried out.

Abstract: An integrated circuit radio frequency (RF) transmitter includes a phase locked loop having a multi-mode loop filter that is operable to provide wide band response with a fast settle time in a startup mode of operation and a relatively more narrow response with a longer settle time but with improved filtering in a steady state mode of operation according to one embodiment of the invention. The multi-mode loop filter includes, in one embodiment, selectable resistance circuitry for selecting between a plurality of resistance values based upon a two-state multi-mode control signal to provide the selected resistance values and selectable capacitance circuitry for selecting between a plurality of capacitance values based upon the two-state multi-mode control signal and for operatively coupling selected capacitors to selected resistors to provide the selected capacitance values.

Abstract: An impedance-matched IQ network includes a phase shift circuit and a back termination. The phase shift circuit includes an in-phase mixer port for receiving the in-phase signal, a quadrature-phase mixer port for receiving the quadrature phase signal, a termination port, and an output port. The back termination is coupled to the termination port of the phase shift circuit, the back termination having an impedance value substantially equal to the characteristic impedance of the phase shift circuit at the termination port.

Abstract: Soft estimate normalization for weighted multiantenna high-order modulation data channel together with separate antenna pilot channels using averaging in first time slots of a transmission time interval with corrections for subsequent time slots.

Abstract: An FFT unit subjects a baseband signal to FFT operation. An IQ-to-phase conversion unit converts an in-phase component value and a quadrature component value of each of a plurality of signals on respective subcarriers subjected to FFT into a phase component value. A phase equalization unit generates a plurality of reference phase values, based on the phase component of each of the plurality of signals on the respective carriers. Further, the phase equalization unit rotates the phase components of the signals on the respective carriers, in accordance with the plurality of reference phase values. A phase correction unit estimates an error in the phase component value of each of the plurality of signals on the respective carriers, based on a phase component of a pilot signal. Further, the phase correction unit rotates the phase component value of each of the plurality of signals on the respective subcarriers for a second time.

Abstract: In a heterodyne receiver, the effect of an image interference signal that occurs in a case where a low intermediate frequency is used is alleviated. Circuits (12I), (12Q), (13I), (13Q), and (14) are provided to switch a heterodyne system between an upper heterodyne system and a lower heterodyne system. The switching circuits (12I) to (14) switch the heterodyne system into one of the upper heterodyne system and the lower heterodyne system with less image interference on the basis of each reception frequency.

Abstract: Embodiments of methods of receiving transmitted signals are disclosed. The methods include a first antenna receiving a second signal, a second antenna receiving a second signal, adjusting a phase relationship between the first signal and the second signal, combining the phase adjusted first signal and second signal, and processing the phase adjusted first signal and second signal to determine the phase adjustment for optimizing at least one of signal to noise ratio and signal to interference ratio of the combined signals.

Abstract: The invention concerns a conditioning circuit (10) for an external signal (IN) representative of a physiological quantity, arranged between an optical sensor (11) and a processing unit (12), the received external signal (IN) being broken down into a useful component and an ambient component, characterized in that the conditioning circuit includes a first stage (13) including a transimpedance amplifier with an incorporated high pass filter (15) using a feedback loop to subtract the ambient signal component from the received external signal, and to deliver at output an amplified useful signal (IN1), a second stage (16) including a blocker sampler circuit (17) for demodulating the amplified useful signal and delivering at output a demodulated useful signal (IN2), and a third stage (18) including a bandpass filter (19) for filtering the demodulated useful signal in the frequency band of the physiological quantity to be detected and for transmitting a conditioned signal (OUT) to the processing unit.

Abstract: The apparatus measures timing variations, such as the jitter or wander in a timing signal (100) of a telecommunications network. A recovered clock signal is sampled and digitized to produce a series of digital clock samples which are then processed (135) with reference to a local digital reference signal to produce digital baseband frequency in-phase (I) and quadrature (Q) components (165, 170) these being further processed (145) to produce the digital phase information of said clock signal to determine (175) the required parameters of the network. The step of digitally processing said clock samples with reference to a local reference signal can be conveniently and cheaply implemented using a digital signal down-converter IC (135), for example of a type existing for digital radio receiver implementations. For jitter measurement, the local reference signal may be generated by a phase-locked loop (as in FIG. 2). For wander measurements an external reference clock is used (as in FIG. 3).

Abstract: In a method for interference suppression using a quality-adjustable bandpass filter in a receiver circuit for carrier-modulated received signals (SIN), the bandpass filtered received signal (Bout) is demodulated, and a switching process is triggered with the demodulated received signal (Dout). In order to eliminate internal or self-induced interferences that would be caused by a switching process in the output portion of the receiver, a quality reduction of the bandpass filter is correlated with the switching process that causes the interference. The method is especially suitable in connection with circuits for infrared receivers, which can thereby be manufactured in a small size, without external components, and thus economically.

Abstract: An adaptive interference canceller for canceling an interfering signal corresponding to a delayed, frequency translated, amplitude and phase offset version of a transmitted signal contained in a composite received signal relayed through a relay system such as a satellite transponder. The canceller digitally downconverts the received signal and a local replica of the transmitted signal from IF to baseband, applies a variable delay and frequency compensation to the replica as a coarse delay and frequency correction, and tracks fine delay, amplitude and phase differences using an adaptive finite impulse response filter to generate a cancellation signal corresponding to the delayed and frequency shifted version. A minimum output power process produces an error signal that drives the variable delay and adaptive filter to minimize the power in the signal of interest to maximize cancellation of the interfering signal.

Abstract: A phase rotation unit rotates the phase of a digital received signal in accordance with a correction signal from a correction determination unit. An FWT computation unit subjects a CCK modulated signal to FWT computation and outputs Walsh transform values FWT. A maximum value searching unit receives Walsh transform values FWT and selects one of them by referring to the magnitude thereof. In accordance with the selected Walsh transform value FWT, the maximum value searching unit outputs a ?1 signal and a ? component signal, the ?1 signal corresponding to the signal prior to ?1 differential detection and the ? component signal being a combination of ?2 through ?4. A ?1 demodulation unit subjects the ?1 signal to differential detection so as to generate ?1. A second phase error detection unit 56 detects a phase error in accordance with an output signal from the ?1 demodulation unit.

Abstract: An in-phase combining diversity receiving apparatus is disclosed by which the size (gain) of a receiving signal as well as its phase is controlled and signals received through each antenna pass through different paths so that an imbalance of receiving signal power is solved. The diversity receiving apparatus includes a first signal adjusting unit for amplifying a first signal received by a first antenna and for phase-shifting, a second signal adjusting unit for amplifying a second signal received by the second antenna and for phase-shifting, and a controller. The controller operates as to measure powers of an original receiving signal, the first signal and the second signal, and controls the first and second signal adjusting units.

Abstract: A direct conversion receiver includes a local oscillator for generating a sinusoid, a mixer for receiving an incoming signal and for mixing the incoming signal with the sinusoid, an analog-to-digital converter for converting the mixed analog signal into a digital signal, and a digital signal processor for outputting the digital signal so that an I-channel signal and a Q-channel signal are output separately and for transmitting to the local oscillator a phase control signal that determines the phase of a sinusoid to be generated by the local oscillator. The direct conversion receiver may further include a low noise amplifier for amplifying the incoming while preventing noise included in the input signal from being amplified, a baseband amplifier for amplifying the mixed analog signal in a baseband, and a baseband low pass filter for removing low frequency noise from a signal amplified by the baseband amplifier.

Abstract: A direct conversion receiver (DCR) calibrated for phase and gain mismatch is provided. The DCR comprises a poly-phase filter that generates mismatched in-phase and quadrature-phase differential signals; the in-phase differential signal is mixed with first and second local oscillation signals; the quadrature-phase differential signal is mixed with third and fourth local oscillation signals; the first and second local oscillation signals have a first adjustable phase mismatch, and the third and fourth oscillation signals have a second adjustable phase mismatch; A mismatch estimation unit (MEU) estimates the entire phase/gain mismatch (signal distortion) of the DCR, The first and second adjustable phase mismatches are adjusted so that the signal distortion of the DCR, as estimated by the MEU is minimized. Thereafter, reduced-component DCRs (without an MEU), calibrated for the mismatches of a poly-phase filter, may be mass produced.

Abstract: In a radio reception apparatus, a quadrature detector provides its digital output signal to a band-limiting filter after lowering a sampling frequency by a sampling frequency converter. Based on a correlation value obtained from an output of the band-limiting filter by a symbol timing detecting circuit, a symbol timing deviation detecting circuit detects a magnitude and a direction of a deviation of the timing of sampling in the sampling frequency converter, and controls timing of the sampling in the sampling frequency converter. Thereby, a symbol point of the correct timing is extracted.

Abstract: Techniques to acquire and track pilots in a CDMA system. In an aspect, frequency acquisition of a number of signal instances (i.e., multipaths) in a received signal may be achieved concurrently based on a frequency control loop (RAFC) maintained for each finger processor of a rake receiver. Upon successful acquisition, frequency tracking of acquired multipaths may be achieved based on a combination of a frequency control loop (VAFC) maintained for an oscillator used for downconverting the received signal and the RAFCs for the finger processors. In a tracking mode, the VAFC tracks the average frequency of the acquired multipaths by adjusting the frequency of the oscillator. The RAFC of each finger processor tracks the residual frequency error (e.g., due to Doppler frequency shift) of the individual acquired multipath by adjusting the frequency of a complex sinusoidal signal used in a rotator within the finger processor.

Abstract: Coherent detection of a received EM signal using universal frequency translation (UFT) is described herein. The received EM signal is sampled according to a sub-harmonic LO signal, where the LO signal is in frequency and phase coherence with the received EM signal. The coherent receiver includes a down-converter/demodulator and a synthesizer/loop filter that are both implemented using UFT technology. The down-converter/demodulator samples the EM input signal using a UFT module according to the coherent sub-harmonic LO signal that is generated by the synthesizer/loop filter. The synthesizer/loop filter generates the coherent LO signal using a phase detector, a loop filter, and an up-converter. The phase detector and up-converter are implemented using UFT modules.

Abstract: A device and a method for automatic frequency correction are used in mobile radio receivers. After channel estimation has been performed, the phases of the received data symbols are analyzed in order to determine the frequency shift. Following the phase analysis, a phase correction of the received data symbols is performed.

Abstract: A diversity receiving apparatus comprises a plurality of antennas, a plurality of receiving circuits connected to the plurality of antennas, respectively, an adding unit for adding reception signals output from the respective receiving circuits, and a plurality phase shifting units for making phases of the reception signals to be input into the adding unit equal. A level comparing unit, for comparing the levels of the reception signals output from the respective receiving circuits, is provided. Phases of reception signals other than a maximum-level reception signal are controlled so as to have the same phase as the phase of the maximum-level reception signal, and the phase-controlled signals are input into the adding unit.

Abstract: A receiver has an adder for output intermediate-frequency signals of a plurality of receiving blocks, a demodulator for an added intermediate-frequency signal, adjustable reference-signal generator for supplying phase-shifted reference signals to the PLL circuits of the plurality of receiving blocks, and a plurality of switches. The switches are controlled when power is first supplied to the receiver such that the frequency-divided reference signals to the PLL circuits are in phase with one another. The adjustable reference-signal generator, upon tuning on power, is set in the phase-shift adjusted state stored immediately before previously turning off the power.

Abstract: A diversity reception device includes a plurality of antennas. A plurality of receiver circuits are connected to the corresponding antennas. An adder adds the received signals output from the receiver circuits. Phase shifters allow the received signals to be input into the adder in phase with each other. A level comparator unit compares the levels of the received signals output from the receiver circuits. A level variable unit is interposed between each of the receiver circuits and the adder, and is controlled by the level comparator unit. Each of the received signals other than the received signal having the maximum level is relatively attenuated by the corresponding level variable unit in accordance with the difference of the level of the received signal from the maximum level before being input into the adder.

Abstract: First and second RF signals in the respective first and second channels of a multiple channel diversity receiver are processed jointly in a joint timing loop filter for baud clock recovery. The channel with the stronger signal determines the frequency of the baud clock for the channel with the weaker signal, leaving the respective PLL's to make individual phase adjustments for each channel. The first and second channels also share a skew corrector for baud clock recovery when the multipath delay between the first and second RF signals is greater than one whole baud clock period. The whole baud skew corrector computes the correlation between the first and second received signals, and if the correlation is low, shifts the first and second signals by one whole baud and recomputes the correlation. The process of shifting the first and second received signals and computing the correlation function is repeated for various whole baud shifts in accordance with a search strategy to find the best (highest) correlation.

Abstract: A method and apparatus for correcting for a phase shift between a transmitter and receiver comprising the steps of: a) transmitting a signal from a transmitter (14); b) receiving the transmitted signal (16) at a receiver (20); c) comparing the received signal (17) to a reference signal; d) if a difference between the reference signal and the received signal (17) is greater than a predetermined value go to step e), if not go to step g); e) adjusting a frequency of the transmitted signal (16); f) go to step a); and g) calibration complete.

Abstract: An adaptive interference canceller for canceling an interfering signal corresponding to a delayed, frequency translated, amplitude and phase offset version of a transmitted signal contained in a composite received signal relayed through a relay system such as a satellite transponder. The canceller digitally downconverts the received signal and a local replica of the transmitted signal from IF to baseband, applies a variable delay and frequency compensation to the replica as a coarse delay and frequency correction, and tracks fine delay, amplitude and phase differences using an adaptive finite impulse response filter to generate a cancellation signal corresponding to the delayed and frequency shifted version. A minimum output power process produces an error signal that drives the variable delay and adaptive filter to minimize the power in the signal of interest to maximize cancellation of the interfering signal.

Abstract: A magnetic communication system includes a transmitter have a single coil transducer, and a receiver having a three orthogonally oriented coil transducers. The signal processing circuitry in the receiver adjusts the phases of the signals received by the three transducers to produce signals which are in-phase. The signals are then summed to provide an output signal from the receiver. The processing circuitry adjusts the phases of the incoming signals either serially or in parallel. Transmissions from the receiver to the transmitter are also phase adjusted in accordance with the same adjustments used in reception.