38 results about "Pilot phase" patented technology

Position determination accuracy of a wireless communication device may be negatively affected by a large unaccounted GPS doppler bias, which in turn may affect GPS doppler estimations and GPS doppler measurements conducted by the wireless communication device. The quality of GPS doppler measurements is very important for position location, because poor quality GPS doppler measurements may prevent the wireless communication device from acquiring satellites in the most sensitive modes with narrow frequency ranges, which results in reduced GPS pseudorange measurement yield. Large unaccounted GPS doppler bias also adversely affects position accuracy because of the adverse effect on the GPS code phase measurements time propagation to common time prior to their use in position location calculation. The same is true in the case of unaccounted CDMA code doppler, through the adverse effect on the AFLT code phase measurements time propagation to common time prior to their use in a position location engine. This effect is the biggest concern in the case of large search windows. Therefore, the present disclosure provides a method of optimizing GPS based position location in the presence of time-varying frequency error, including the steps of continuously measuring and / or calculating resulting GPS doppler bias and CDMA code doppler bias and then minimizing their adverse effects with regard to position location determination by re-centering GPS doppler search windows based on the GPS doppler bias value, as well as using GPS doppler bias and CDMA code doppler bias value to properly propagate GPS pseudorange and AFLT pilot phase measurements, respectively, to common time prior to their use in a position location engine.

A multi-carrier (MC) receiver receives a multi-carrier signal containing data symbols as well as pilot symbols. The MC receiver estimates a carrier frequency offset in a downconverted base-band multi-carrier signal in the frequency domain based on deviations of one or more characteristics of the pilot signals from predetermined values, and corrects for the offset in the time domain. In an embodiment, a second order phase locked loop (PLL) estimates the phase of the pilot signals to determine the carrier frequency offset. Changes in pilot phases caused due to the time domain correction are cancelled to allow the PLL to minimize deviations from the lock position.

A method for compensating frequency deviation of sampling clock on OFDM receiver includes using FFT window controller to control FFT window position for picking up pilot phase deviation angle in current OFDM symbol to derive out offset amount crude estimation of current FFT window, using accumulated average of FFT window offset amount to estimate FFT window offset amount of OFDM symbol accurately, using this accurate offset amount to regulate each sub channel phase after current OFDM symbol is balanced and simultaneously using this accurate offset amount to judge whether FFT window of next OFDM symbol is displaced or not.

A method, a system and a receiver device provide timing and frequency correction in a spatial division multiple access (SDMA) system. A timing and frequency correction (TFC) logic / utility obtains a timing error estimate by using pilot symbols on a slot of six tiles. The TFC logic estimates the timing error based on pilot phase differences between unique pairs of tiles when the frequency separation of the tiles is less than a threshold value. When none of the unique pairs of tiles satisfies the threshold value, the TFC logic estimates timing error based on an exhaustive search for each candidate phase error value. The TFC logic performs timing error correction via a timing error estimate based on pilots from the symbols received on each antenna. The TFC logic performs inexplicit frequency error correction according to phase differences based on relative symbol indices.

A receiver comprises a multiple source phase estimator. The latter comprises a pilot-phase estimator, a data-driven average phase estimator, a selector and a common interpolation controller. The selector selects either the pilot-phase estimator or the data-driven average phase estimator as the source of determined phase estimates at particular times. At other times, the common interpolation controller provides interpolated phase estimates as a function of a linear interpolation based on a respective determined phase estimate.

A multi-carrier (MC) receiver receives a multi-carrier signal containing data symbols as well as pilot symbols. The MC receiver estimates a carrier frequency offset in a downconverted base-band multi-carrier signal in the frequency domain based on deviations of one or more characteristics of the pilot signals from predetermined values, and corrects for the offset in the time domain. In an embodiment, a second order phase locked loop (PLL) estimates the phase of the pilot signals to determine the carrier frequency offset. Changes in pilot phases caused due to the time domain correction are cancelled to allow the PLL to minimize deviations from the lock position.

The invention relates to a self-adaptive damage compensation method and system for a digital-related optical communication system. The self-adaptive damage compensation method includes inserting two pulse modulation pilot frequency signals symmetrically distributed on an input signal frequency fc (fiber channel) at a transmitting terminal; acquiring an input signal power spectrum by the Fourier transform at a receiving terminal, and receiving the pilot frequency signals of a signal power spectrum and subjecting the pilot frequency signals to location and filtering extraction; calculating size of frequency offset of a vibration laser and performing compensation by a pilot frequency; acquiring pilot time domain waveforms by the Fourier transform and calculating a delay delta tau between two pilot light pulses, and calculating size of dispersion by the delta tau and performing the compensation; finally extracting pilot phase noises and subtracting the same from a signal phase so as to eliminate laser phase noises and nonlinear fiber damages. The self-adaptive damage compensation method has the advantages of high accuracy, low complexity, small occupation of bandwidth and fast response speed, so that self-adaptive compensation of various damages can be realized.

In a receiver, a decision-directed phase estimator is used in conjunction with an interpolator to provide a phase estimate for use in carrier recovery. For example, a receiver comprises a pilot phase estimator, a Costas loop and an interpolation controller. The pilot phase estimator provides determined phase estimates at the pilot times and the interpolation controller provides interpolated phase estimates at other times as a function of a linear interpolation based on a respective determined phase estimate and at least one decision-directed phase error estimate from the Costas loop.

Disclosed is a system, a method and a computer product for synchronizing of a femto cell with a macro cell. The method comprises placing a forward link receiver into the femto cell; receiving by a micro cellular network the femto cell transmission timing; and synchronizing the femto cell transmission timing with the macro cellular network transmission timing in reliance on the forward link receiver signal. Further, a system, a method and computer product for allocating pilot phases to femto cells, the method comprising: creating at least as many new potential pilot phases for femto cells as there are for macro cells; and allowing a mobile device on a macro cell to search and find a femto cell pilot without explicitly listing femto pilot phases in the neighbor list.

The invention relates to a method for realizing a passive oriented buoy digital de-multiplexer. The input is passive oriented buoy composite signal undergoing A / D sampling and digital discretization, and the output is omnidirectional signal, east-west signal, north-south signal and locking state signal undergoing the digital discretization. The method comprises the following steps of: firstly, digitally filtering the composite signal to separate the omnidirectional signal, the dipole quadrature modulation signal and the pilot frequency signal, wherein the frequency of the pilot frequency signal is tracked and locked by a pilot frequency phase locked loop so as to further track and lock the phase of the pilot phase signal, provide the sinusoidal and cosine signals with the same frequency and phase, and demodulate the dipole signal undergoing quadrature modulation; further performing the lowpass filtering, outputting the omnidirectional signal, the east-west signal and the north-south signal; and locking the information whether the output value given by a judging module is valid. The method has the advantages of reducing the complexity of a buoy receiver, simplifying the hardware design, eliminating the influence of simulated elements, ensuring the balance of two dipole symmetrical channels and improving reliability and oriented precision.

The invention relates to a test method for the environmental adaptability of an optical fiber sensing system. The test method includes three parts: a hardware connection stage, a test preparation stage and a test stage: the hardware connection stage includes: preparing a temperature and humidity environment test box, and a prototype to be tested , industrial computer, double-layer shielded network cable, power cord and optical fiber disk; the test preparation stage includes: starting the prototype to be tested and the industrial computer and making the network communication between the two normal, and then opening the system control software in the industrial computer to start monitoring the operation of the prototype to be tested status; the test phase includes setting various temperatures and operations and monitoring test results to draw monitoring conclusions. The test method of the present invention selects the most severe working and operating temperature and humidity environment of the product, and allows the product to operate in its extreme environment, thereby providing assistance for device selection and design improvement. During the test, the product is run online and monitored in real time , by comparing the conditions and data before the test, under the high temperature test, under the low temperature test and under the damp heat test.

An analog mobile station system includes a man-machine interaction module, a control module, a test data derivation module, a database management module and a code / de-code module. An analog mobile station location test system includes: an analog mobile station system, a mobile location center, a location entity and a satellite data receiver. The test method includes: finishing the designing of the test request by the man-machine interaction module and transmits it to the control module to set the time trigger of each test task and the control module sets up the connection with the location entity based on the TCP / IP, the test data derivation module finishes the calculation of pilot phase and satellite false distance, the control module finishes the signaling interaction with the location entity on the location flows by the calculated data to transmit the position result computed by the location entity to the man-machine interaction module.