Mediatek Corporation

Kun-tso Chen

Chun-Nan Chen

Kung-Shuan Huang

Kung-shuan Huang

Jui-Ming Wei

Kuan-I Li

Wen-Cheng Lai

Jan-shin Ho

A data signal phase reversal correction method and system implementing the same are disclosed. In the present invention, a pilot signal of a satellite is checked to see if there is a phase reversal according to an accumulation of correction results of symbols of the received pilot signal with corresponding symbols of a known pilot sequence. It is determined whether a phase correction of a data signal of the satellite is to be executed or not by referencing the phase reversal determination result of the pilot signal.

Data signal phase reversal correction method and system implementing the same

A BOC signal acquisition and tracking apparatus and method. In the present invention, at least a BOC signal, a BOC-cos signal and a PRN coded signal are generated for a received signal. Depending on application condition (e.g. acquisition mode or tracking mode), autocorrelation of the BOC signal is combined with cross-correlation of the BOC signal and one of the BOC-cos signal and the PRN coded signal to generate a proper combined correlation result.

BOC signal acquisition and tracking method and apparatus

A correlation device and method is provided. According to the present invention, the correlation device comprises a first signal path for receiving a received signal; at least one second signal path for receiving the received signal and eliminating effect of a subcarrier component of the received signal; and a correlation unit couple to the first signal path and each second signal path, for selecting an output of one of the first and second signal paths to execute signal correlation.

Correlation device and method

A clock system includes a clock signal generating circuit and a controlling circuit. The clock signal generating circuit is used for generating a primary clock signal and a reference clock signal both derived from an oscillating signal of the clock signal generating circuit. The controlling circuit is coupled to the clock signal generating circuit and used for receiving the primary clock signal under a normal mode and compensating timing information generated from the primary clock signal according to the reference clock signal when the clock system exits a power saving mode. The primary clock signal is de-activated when the clock system enters the power saving mode and is activated when the clock system exits the power saving mode. The clock system can keep a continue clock for system to use when the primary clock signal is gated or power saving mode is entered.

Clock system and method for compensating timing information of clock system

The invention provides a signal receiver. The signal receiver comprises a carrier removal module, a Fast Fourier Transformation (FFT) module, and a signal processor. The carrier removal module generates a carrier signal with a frequency of an estimated carrier frequency, generates at least one delta carrier signal with a frequency of the carrier frequency plus a delta frequency, removes the carrier signal from a first signal to obtain a second signal, and removes the delta carrier signal from the first signal to obtain a third signal. The FFT module derives a series of first FFT values from the second signal, and derives a series of second FFT values from the third signal. The signal processor estimates the carrier frequency of the second signal to obtain the estimated carrier frequency, determines the delta frequency for the carrier removal module, estimates a residual Doppler frequency of the second signal according to both the first FFT values and the second FFT values, and adjusts the estimated carrier frequency according to the residual Doppler frequency.

Signal receiver and method for estimating residual doppler frequencies of signals thereof

A sync detection device and method for a GNSS receiver. In modernized GNSS, each satellite transmits a data signal and a pilot signal. Correlations are performed between a data symbol stream converted from the data signal with possible hypotheses to find a leading edge of a frame of the data signal (i.e. frame sync detection) and between a pilot symbol stream converted from the pilot signal with possible hypotheses to find a leading edge of a code sequence of the pilot signal (i.e. pilot sync detection). The possible hypotheses for the frame sync detection are selected according to a result of pilot sync detection when pilot sync is done. Frame sync can be efficiently achieved since a range of the selected possible hypotheses is quite limited.

Sync detection device and method for GNSS

A correlator for a GNSS receiver and a code generator used in the correlator as well as a correlation method are disclosed. In the GNSS, each satellite transmits a data signal and a pilot signal. The correlator is adaptable for executing correlation to the data signal, the pilot signal and various combinations thereof, such as non-coherent and coherent combinations. The code generator generates primary ranging codes of the data and pilot signals as well as various combinations thereof, such as sum or difference of the primary ranging codes of the data and pilot signals. By using the various codes, the correlator is adaptable and flexible for different correlation requirements.

GNSS data/pilot correlator and code generator thereof

A method for determining boundaries of information elements for a PRN code modulated signal is provided. The method of the present invention measures a symbol phase of the received signal and correlation values of different durations to determine the information element boundary. By the method of the present invention, the determination of the information element boundary can be more effective especially in the common dump receiver architecture, wherein a reference wave used in the correlation measurement of the receiver cannot match the received waveform exactly.

Method and apparatus for determining boundaries of information elements

A Doppler frequency searching method and correlator are disclosed. In the present invention, before Doppler frequency removal, a received signal is converted into digital form having a first sampling rate. Then the signal is down-sampled to have a low sampling rate. The Doppler frequency searching is done by stages. Each stage is in charge of a portion of the Doppler frequency to be removed. The sampling rate can be further reduced in each stage. Each stage can have at least one Doppler frequency removal unit sharing the portion of Doppler frequency that the stage is to remove. Power consumption is reduced since Doppler frequency removal is executed with low sampling rate.

Signal acquisition/tracking method and correlator for the same

The invention provides a signal receiver. The signal receiver comprises a code removal module, a carrier removal module, a Fast Fourier Transformation (FFT) module, and a signal processor. The code removal module removes a pseudo random noise code from a first signal to obtain a second signal. The carrier removal module generates a carrier signal with a frequency of an estimated carrier frequency, generates at least one delta carrier signal with a frequency of the carrier frequency plus a delta frequency, removes the carrier signal from the second signal to obtain a third signal, and removes the delta carrier signal from the second signal to obtain a fourth signal. The FFT module derives a series of first FFT values from the third signal, and derives a series of second FFT values from the fourth signal. The signal processor estimates the carrier frequency of the second signal to obtain the estimated carrier frequency, determines the delta frequency for the carrier removal module, estimates a residual Doppler frequency of the third signal according to both the first FFT values and the second FFT values, and adjusts the estimated carrier frequency according to the residual Doppler frequency to eliminate distortion from residual Doppler effects from the third signal. The delta frequency is lower than a frequency resolution of the FFT module.

A correlation device and method for different modulated signals such as BPSK signal and BOC signal. According to the present invention, the correlation device has one or more sections. Each section comprises a correlation unit for executing correlation; a first signal path for passing a received signal directly to the correlation unit; a second signal path for transferring a BOC signal into a BPSK-like signal and passing the signal to the correlation unit. The correlation unit has a multiplexer for selecting to allow an output of one of the first and second signal paths to be subject to signal correlation. The correlation results of the respective sections can be combined.

Correlation device and method for different modulated signals

A satellite search method and a receiver implementing such a method are disclosed. In the present invention, a predetermined range is sampled into multiple possible positions or space-time points, each of which is defined by a specific position and a time sample. The possible positions or points are sieved according to a search result of a satellite selected from candidate satellites each time. By repeatedly doing so, the finally remaining position will approach a user's position, and accordingly the candidate satellites converge to the most possible ones as to facilitate satellite search.

Satellite search method and receiver using the same

A satellite time dynamic search method and a receiver implementing such a method are disclosed. In the present invention, a predetermined period of time is sampled into multiple time samples. The time samples are sieved according to a search result of a satellite selected from candidate satellites each time. By repeatedly doing so, the finally remaining time sample will approach a true satellite system time, and accordingly the candidate satellites converge to the most possible ones as to facilitate satellite search.

A Doppler frequency searching method and correlator are disclosed. In the present invention, before Doppler frequency removal, a received signal is converted into digital form and the spreading code is removed. Then the signal is down-sampled to have a low sampling rate, which can be determined according to the maximum Doppler frequency to be searched. The Doppler frequency searching is done by stages. Each stage is in charge of a portion of the Doppler frequency to be removed. The sampling rate can be further reduced in each stage. Each stage can have a plurality of Doppler frequency removal units sharing the portion of Doppler frequency that the stage is to remove. Power consumption is reduced since Doppler frequency removal is executed with low sampling rate.

A method for searching satellites in a cold start state. The method of the present invention, a first satellite, which is predetermined or randomly selected, is searched. Then, a second satellite to be searched is selected according to the searching result (hit or missed) for the first satellite and respective interrelationships between the first satellite and the other satellites. In practice, an initial weight factor table is provided. Depending on the searching result, the initial weight factor table is updated according to the interrelationships between the satellites during searching. By using the method of the present invention, the time-to-first-fix (TTFF) can be reduced to a shorter period of time so as to provide a rapid cold start satellite positioning.

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Fang-Yuan Hsiang, Taiwan

Kun-tso Chen