1117 results about "Quadrature signal" patented technology

A system and method are disclosed for the management of WLANs in cases where unmanaged access points are present as well as with the addition or removal of access points. The disclosed system and method use signal data and network traffic statistics collected by mobile units to determine optimal configuration settings for the access points. The access point settings so managed can include the operating channel or center frequency, orthogonal signal coding used (optionally including the data rate), if any, and the transmission power. The solutions computed can account for the inherent trade-offs between wireless network coverage area and mutual interference that may arises when two or more access points use the same or overlapping frequency bands or channels and the same or similar signal coding.

A method for detection on a digitizer sensor, the method comprises simultaneously transmitting orthogonal signals having the same frequency on at least two conductors of a digitizer sensor; sampling a signal on at least one other conductor crossing the at least two conductors, wherein the signal is responsive to capacitive coupling at cross-junctions formed between the at least two conductors and at least one other conductor; decomposing the sampled signal into orthogonal components; and analyzing the orthogonal components to detect user interaction at each cross junction.

The present invention provides an approach for quadrature signal generation, which does not require orthogonal reference signals or nearly orthogonal reference signals as an input or given condition. The techniques provided herein can utilize a reference phase shift less than 90° but greater than 0°, along with an inversion to create orthogonal signals. The techniques provided here reduce the number of critical manipulations required from a hardware perspective.

A system and a method for distance measurement utilizes a radio system. The distance is measured by determining the time it takes a pulse train to travel from a first radio transceiver to a second radio transceiver and then from the second radio transceiver back to the first radio transceiver. The actual measurement is a two step process. In the first step, the distance is measured in coarse resolution, and in the second step, the distance is measured in fine resolution. A first pulse train is transmitted using a transmit time base from the first radio transceiver. The first pulse train is received at a second radio transceiver. The second radio transceiver synchronizes its time base with the first pulse train before transmitting a second pulse train back to the first radio transceiver, which then synchronizes a receive time base with the second pulse train. The time delay between the transmit time base and the receive time base can then be determined. The time delay indicates the total time of flight of the first and second pulse trains. The time delay comprises coarse and fine distance attributes. The coarse distance between the first and second radio transceivers is determined. The coarse distance represents the distance between the first and second radio transceivers in coarse resolution. An in phase (I) signal and a quadrature (Q) signal are produced from the time delay to determine the fine distance attribute. The fine distance indicates the distance between the first and second transceivers in fine resolution. The distance between the first and second radio transceivers is then determined from the coarse distance and the fine distance attributes.

The present invention provides an approach for quadrature signal generation, which does not require orthogonal reference signals or nearly orthogonal reference signals as an input or given condition. The techniques provided herein can utilize a reference phase shift less than 90° but greater than 0°, along with an inversion to create orthogonal signals. The techniques provided here reduce the number of critical manipulations required from a hardware perspective.

The present invention is directed to a broadband electric-magnetic antenna apparatus and method. The present invention teaches a variety of electric antennas suitable for use in the present invention as well as a variety of magnetic antennas suitable for use in the present invention. Combination of a broadband electric antenna element and a broadband magnetic element to create a broadband electric-magnetic antenna system is discussed. This invention further teaches systems for using a broadband electric magnetic antenna system to radiate or receive quadrature signals.

When cables run side by side over a longer distance, an alternating-current signal used for cable location can couple or ‘bleedover’ to neighboring cables. The coupled current flowing in the neighboring cable creates field distortion and makes position determination of the targeted cable difficult. The resulting magnetic field of both (or more) cables has a non-circular shape and is commonly known as a distorted field. Established methods for finding the position of the cable under investigation lead to inaccuracies or even wrong locates. The method described herein eliminates the field distortion that is due to the coupled cables by demodulating a phase reference signal placed on the cable by a transmitter into two signal strength constituents. The inphase signal represents the field strength of the targeted conductor and is substantially free of field distortion. The other quadrature signal contains the component of the field associated with distortion.

The present invention is directed to a broadband electric-magnetic antenna apparatus and method. The present invention teaches a variety of electric antennas suitable for use in the present invention as well as a variety of magnetic antennas suitable for use in the present invention. Combination of a broadband electric antenna element and a broadband magnetic element to create a broadband electric-magnetic antenna system is discussed. This invention further teaches systems for using a broadband electric magnetic antenna system to radiate or receive quadrature signals.

System and methods are provided for multi-path orthogonal recursive predistortion. The systems and methods may include generating a first orthogonal signal and a second orthogonal signal, where the first and second signals are orthogonal components of an input signal and processing, at a first predistortion module, the first orthogonal signal and a first error correction signal to generate a first predistorted signal. The system and methods may also include processing, at a second predistortion module, the second orthogonal signal and a second error correction signal to generate a second predistorted signal, and providing the generated first and second predistorted signals to a nonlinear device, where the nonlinear device generates an output based upon the first and second predistorted signals, where the first error correction signal is determined based upon an analysis of the output and the first predistorted signal, and where the second error correction signal is determined based upon an analysis of the output and the second predistorted signal.

A method and system for digital spur cancellation may include removing a spur in a left channel minus right channel (L−R) baseband signal generated from a FM signal. The L−R baseband signal may be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. An orthogonal signal may also be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. The phase of the orthogonal signal may be further adjusted to introduce a substantially −90° phase shift to spurs at a specific frequency. Accordingly, the spurs in the L−R baseband signal may be cancelled when the first L−R baseband signal is combined with the phase adjusted orthogonal signal.

A receiver is provided for a quadrature-modulated signal, which can be divided into an inphase signal and a quadrature signal. The inphase signal is fed to first and third equalizers, and the quadrature signal is fed to second and fourth equalizers, wherein the first and second equalizers each perform a first equalization of the respective signal. An output of the first equalizer is connected to a second input of the fourth equalizer, which, by means of a second equalization of the quadrature signal, transmits an equalized quadrature signal as a function of the previously fed equalized inphase signal of the first equalizer. An output of the second equalizer is connected to the second input of the third equalizer, which, through a second equalization of the inphase signal, transmits an equalized inphase signal as a function of the previously fed equalized quadrature signal of the second equalizer.

An apparatus for receiving a signal includes a training signal generator generating a training signal corresponding to each frequency channel; an IQ signal generator generating a first in-phase signal and a first quadrature-phase signal using the training signal in a first operation mode and generating a second in-phase signal and a second quadrature-phase signal using a receiving signal in a second operation mode; an IQ mismatch compensator which makes the first in-phase signal and the first quadrature-phase signal generated in response to each frequency channel converge for a reference time in the first operation mode to obtain a phase mismatch compensation coefficient and after obtaining a phase mismatch compensation coefficient with respect to selected frequency channels and generating a look-up table using the phase mismatch compensation coefficient, compensates the second in-phase signal and the second quadrature-phase signal using the phase mismatch compensation coefficient included in the look-up table in the second operation mode; and a memory in which the look-up table is stored.

A micro-gyroscope (10) having closed loop output operation by a control voltage (Vty), that is demodulated by a drive axis (x-axis) signal Vthx of the sense electrodes (S1, S2), providing Coriolis torque rebalance to prevent displacement of the micro-gyroscope (10) on the output axis (y-axis) Vthy˜0. Closed loop drive axis torque, Vtx maintains a constant drive axis amplitude signal, Vthx. The present invention provides independent alignment and tuning of the micro-gyroscope by using separate electrodes and electrostatic bias voltages to adjust alignment and tuning. A quadrature amplitude signal, or cross-axis transfer function peak amplitude is used to detect misalignment that is corrected to zero by an electrostatic bias voltage adjustment. The cross-axis transfer function is either Vthy / Vty or Vtnx / Vtx. A quadrature signal noise level, or difference in natural frequencies estimated from measurements of the transfer functions is used to detect residual mistuning, that is corrected to zero by a second electrostatic bias voltage adjustment.

A method and system for increasing the effective communications channel bandwidth beyond that of the constrained physical bandwidth of a given channel by orthogonal signal spectrum overlay (OSSO) comprising: decomposing the time-bandwidth product (TBP) of a given symbol in a data stream transmitted through a given bandwidth, expanding the TBP in terms of overlaid orthogonal signals such as Weber-Hermite (WH) functions that constitute the eigensignals of the symbol. The complete data stream is multiplexed to produce a plurality of data channels, each of which is encoded on an orthogonal signal by quadrature amplitude modulation. The overlay of these signals constitutes the OSSO symbol. The OSSO symbols are transmitted in quadrature format (I and Q) and are the result of the addition of orthogonal signals, each of which constitutes a separate overlaid communication channel, occupying the same physical bandwidth.

Digital transmitters having improved characteristics are described. In one design of a digital transmitter, a first circuit block receives inphase and quadrature signals, performs conversion from Cartesian to polar coordinates, and generates magnitude and phase signals. A second circuit block (which may include a delta-sigma modulator or a digital filter) generates an envelope signal based on the magnitude signal. A third circuit block generates a phase modulated signal based on the phase signal. The third circuit block may include a phase modulating phase locked loop (PLL), a voltage controlled oscillator (VCO), a saturating buffer, and so on. A fourth circuit block (which may include one or more exclusive-OR gates or an amplifier with multiple gain states) generates a digitally modulated signal based on the envelope signal and the phase modulated signal. A fifth circuit block (which may include a class D amplifier and / or a power amplifier) amplifies the digitally modulated signal and generates an RF output signal.

The present invention discloses a new type of extremely low-noise phase-frequency detector (PFD) 500, broadband from DC to multi-GHz RF frequencies for PLL synthesizer applications. Free of any feedback mechanisms, thus inherently fast, it operates close to transition frequency fT of IC processes or frequency limits of discrete mixers. The PFD 500 utilizes complex SSB conversion in both the in-phase and quadrature arms, delaying the in-phase arm in 530, beating the delayed signal 124 with the un-delayed quadrature signal 122 in mixer 126. The output 128 contains both the frequency difference and the phase difference information between the two signals 118 and 520, providing both the frequency-discrimination (FD) and the phase detection (PD) functions. Utilizing standard mixers the PFD 500 can achieve superior CNRs of 180 dBc / Hz at multi-GHz RF. Additionally, utilizing the FD / FM demodulation capability, the present invention improves phase noise of various signals and linearity of FM modulators.

A quadrifilar helical antenna comprising two pairs of filars having unequal lengths and phase quadrature signals propagating thereon. A conductive H-shaped impedance matching element matches a source impedance to an antenna impedance. The impedance matching element having a feed terminal at the center thereof from which current is supplied to the two filars of each filar pair disposed about an edge of the impedance matching element and symmetric with respect to a center of the impedance matching element. The impedance matching element further comprises a reactive element for matching the antenna and source impedances.

The present invention discloses an ultrasound imaging system and method based on simultaneous multiple transmit-focusing using the weighted orthogonal chirp signals so that resolution of an ultrasound image is enhanced without sacrifice in the frame rate. The ultrasound imaging system according to the present invention includes: a storing means for storing weighted orthogonal signals including N number of orthogonal codes wherein the orthogonal codes are orthogonal to each other; a transmitter for transmitting simultaneously the weighted orthogonal signals as ultrasound transmission signals to corresponding N number of focal points within the target object; a receiver for receiving signals reflected from the N number of focal points corresponding to the transmitted ultrasound signals; a pulse-compressor for pulse-compressing with respect to each orthogonal code by extracting the stored N number of orthogonal codes from the reflected signals; a producer for producing receive-focused signals from the pulse-compressed signals; and a display for displaying the receive-focused signals by processing them. As a result, transmission signals are simultaneously transmitted to the plurality of focal points and received signals are separated on reception, thereby improving resolution without sacrifice in the frame rate.

Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal and a processor for decoding the layered in-phase signal and the layered quadrature signal to produce one or more discrete layer signals.

An apparatus and method to control signal phase in a radio device includes a phase rotator configured to control a phase of a local oscillator. A phase error determination module is configured to determine phase error information based on received in-phase (I) and quadrature (Q) (IQ) signal values. A phase correction module is configured to derive from the received IQ signal values a correction signal and apply the correction signal to the phase rotator in a path of the local oscillator.

A method is disclosed to correct the IQ mismatch of an RF transceiver. The method generates a reference signal down a transmitting-receiving loop and measures the received signals SDTA-1 and SDTA-2, respectively dominated by their desired component and image component, under two programmed mixer settings of operating mode and LOF. The method then calculates a system image rejection ratio (IRRsys) with SDTA-1 and SDTA-2, systematically adjusts the amplitude and phase pre-distortion of the transmitting baseband signals till IRRsys is maximized thus correcting for the transmitter IQ mismatch. The now-corrected transmitter IQ mismatch is then used to correct receiver IQ mismatch by reprogramming the first setting and measuring mismatches in amplitude ΔA and phase Δφ between received baseband IQ signals, corrects for ΔA and Δφ accordingly and stores the corrective values for future compensation of receiver IQ mismatch. The systematic pre-distortion can be implemented using a look-up table or analytical calculation.

The invention provides a method for constructing a thinned MIMO (Multiple Input Multiple Output) planar array radar antenna, which is on the basis of a phase center approximation principle and combines an MIMO antenna thought. The antenna arrangement optimal design is carried out by adopting the MIMO antenna thought. When all transmitting array elements simultaneously (or in turns) transmit orthogonal signals and receiving array elements simultaneously receive echo signals, a virtual planar array with uniform intervals is subjected to equivalence processing by utilizing the phase center approximation principle. According to the thinned MIMO planar array radar antenna constructed according to the invention, few transmitting antenna array elements and few receiving antenna array elements can be adopted and the equivalent full-array-element arrangement planar antenna array is virtually realized. Compared with the planar array antenna which is the same size as the equivalent virtual planar array and is directly arranged, the thinned MIMO planar array radar antenna constructed according to the method disclosed by the invention has the advantage of greatly reducing the requirement on the number of the array elements.

Signal processing under attenuated transmission conditions. Within an orthogonal signal space, the number of orthogonal signals that are used to transmit information from a transmitter to a receiver is reduced and the transmitted power of each of the now remaining orthogonal signals is modified; this may involve increasing the power of all of the remaining orthogonal signals equally or alternatively modifying them individually. The same modulation used before the reduction may also be used afterwards; within communication systems having multiple transmitter-receiver paths, this will ensure that the communication system's throughput and efficiency will remain unchanged even when one (or more) transmitter-receiver paths are highly attenuated. In addition, robust mode operation is provided for ranging and registering of transmitter devices when entering the communication system. In addition, the unused orthogonal signals may be employed to support interference cancellation of those orthogonal signals that are used to transmit information.

A bandpass sampling receiver is proposed for receiving RF signals, comprising: the first ADC, for converting the RF signal into the first path of digital signal under the control of the first sampling clock signal; the second ADC, for converting the RF signal into the second path of digital signal under the control of the second sampling clock signal; a signal separating unit, for separating the in-phase signal and the quadrature signal in the first path of digital signal and the second path of digital signal; wherein the frequency of said first sampling clock signal and said second sampling clock signal is l / N of that of said RF signal, and N is a natural number.

A system and method for the iterative detection and demodulation of M-ary orthogonal signals (MOK) and signals modulated using Complementary Code Keying (CCK) is described. An important feature of these methods is the good performance of noncoherent detectors in AWGN channels. However, the performance of these detectors in fast fading channels degrades considerably compared to that of coherent detectors. Iterative detection algorithms that significantly improve the performance of the demodulators with minimal additional complexity are presented The methods use soft decoder output feedback and iterative demodulation and decoding to achieve performance close to that of coherent detection. For MOK, significant performance enhancement is possible even without any loss of throughput due to insertion of pilot symbols. For CCK pilot symbols are necessary but the throughput loss remains low.

The present invention discloses a new type of extremely low-noise phase-frequency detector (PFD) 500, broadband from DC to multi-GHz RF frequencies for PLL synthesizer applications. Free of any feedback mechanisms, thus inherently fast, it operates close to transition frequency fT of IC processes or frequency limits of discrete mixers. The PFD 500 utilizes complex SSB conversion in both the in-phase and quadrature arms, delaying the in-phase arm in 530, beating the delayed signal 124 with the un-delayed quadrature signal 122 in mixer 126. The output 128 contains both the frequency difference and the phase difference information between the two signals 118 and 520, providing both the frequency-discrimination (FD) and the phase detection (PD) functions. Utilizing standard mixers the PFD 500 can achieve superior CNRs of 180 dBc / Hz at multi-GHz RF. Additionally, utilizing the FD / FM demodulation capability, the present invention improves phase noise of various signals and linearity of FM modulators.

A transmit chain comprises a transmit path with a quadrature up-converter which up-converts quadrature signal components to RF. An observation path samples a portion of the RF signal and a quadrature down-converter down-converts the RF signal to baseband quadrature signal components. A local oscillator signal source provides the up-converter and the down-converter with a local oscillator signal and is operable in two states. In a second of the states the local oscillator signal is applied to the up-converter and the down-converter and a phase shift is made to the signal applied to up-converter or the down-converter compared to the first of the states. A processor monitors properties of the down-converted signal while the local oscillator signal source is operating in the first state and the second state. The processor calculates a correction to apply to the baseband observation signal to correct for errors introduced by the observation path. The processor also calculates a correction to apply to the input signal to correct for errors introduced in the transmit path.

The present invention utilizes circuitry, already present in receivers, to calibrate and correct for gain and phase errors in a transceiver device. The present invention employs a digital signal processor along with multiple phase shifters and all pass networks to ensure proper levels of quadrature signals within the transceiver. An internally generated double sideband suppressed carrier signal is created to produce the calibration signals used by the digital signal processor.

The present invention is directed to a network that includes an output matching network coupled to an amplifier. The output matching network is configured to transform the at least one amplifier transistor output impedance to an output matching network impedance. A combiner network is coupled to the output matching network. The combiner network includes a first quarter wavelength transmission line coupled between the in-phase signal path and a combiner node. The combiner network further includes a bandwidth enhancement element coupled to the quadrature signal path at the combiner node and an impedance transformation element coupled between the combiner node and a load. The impedance transformation element is configured to substantially transform a combined output matching network impedance at the combiner node to the load impedance.

Pre-distortion apparatuses and methods for a non-linear component are provided. The apparatus comprises an adaptive block for generating a plurality of correlation coefficients, which are used to weight a plurality of synthesis work functions to pre-distort a given signal. The adaptive block can be driven by an error signal generated from a feedback signal from the non-linear component output signal and a delayed version of the input signal. The apparatus is capable of being operated directly at radio frequency. Also provided are apparatuses and methods for generation of quadrature signals, transconductance amplification employing negative resistance, variable-gain amplification, and envelope detection.