48 results about "Circular correlation" patented technology

The invention provides a device and a method for correcting error estimation of an analog-digital converter. The method comprises the steps as follows: generating a control signal to finely adjust a numerical control simulation time delay unit according to a correction parameter initial value which is set in advance to adjust time delay amount and correct clock phase error among channels; correcting gain error among channels according to the correction parameter initial value and generating a totality correction signal, buffering the totality correction signal and triggering a counting unit to count, simultaneously calling the totality correction signal in a cache and generating an initial estimation result by using a circular correlation method; setting enabling ends of a low pass filter accumulation unit and a correction parameter updating unit while counting to a preset value, generating the error estimation with the initial estimation result and latching, updating a clock correction parameter and a gain correction parameter according to a gradient descent method, and latching the clock correction parameter and the gain correction parameter, and resetting to correct circulation estimation. The device and the method of the invention improve the estimated accuracy and quickens convergence rate of the estimation correction under the condition of using few effective sample points.

A method of acquiring a weak signal includes selecting a first predetection integration time (PIT) interval for processing a digital intermediate frequency (IF) signal, selecting a number of data bit edges within the PIT, computing a plurality of coherent integrations for each data bit edge, selecting a coherent integration, which corresponds to a most likely data combination for each data bit edge, from the plurality of coherent integrations, updating an incoherent integration total for each data bit edge with the coherent integration corresponding to the selected most likely data bit combination for each data bit edge, comparing the incoherent integration total for each data bit edge with a threshold after a predetermined number of steps of the coherent integration computations and incoherent integration total updates, and identifying a code delay from the incoherent integration. The method may also include determining a code delay from an estimated Doppler shift corresponding to the identified code delay. In this method, the coherent integrations are computed using a circular correlation technique that is performed in a manner so the coherent integrations are not independent from one another in successive steps. Thus, computational efficiencies may be gained from subsequent uses of coherent integrations computed during previous steps. The circular correlation is preferably performed over intervals corresponding to the separation between data bit edges.

A method of acquiring signals from satellites in a Global Positioning System (GPS) is disclosed. The method includes receiving navigation signals from the satellites of the GPS, down-converting to complex baseband the received navigation signals to form a first signal, digitizing samples of the first signal, nonlinear processing of the digitized samples of the first signal to form a second signal, where the nonlinear processing comprises forming a weighted sum of products of pairs of the digitized samples at different relative delays, in which one of each of the pairs has been complex conjugated, coherent averaging the second signal over integer multiples or submultiples of a spreading sequence period of the navigation signals to form a third signal, performing circular correlation processing of the third signal with a representation of each navigation signal of the navigation signals and determining a timing offset at which a correlated output energy is maximized, based on the circular correlation processing.

The invention is applicable to the field of Time division duplexing-long term evolution (TDD-LTE) system communication and provides a TDD-LTE downlink synchronizing method. The method includes obtaining half-frame synchronization information and serial numbers in a cell identity (ID) group; determining a cyclic prefix (CP) type; subjecting a frequency domain secondary synchronization sequence to de-interleaving and descrambling to obtain an even sequence and an odd sequence respectively; subjecting the even sequence and a secondary original sequence to circular correlation and recording a coordinate corresponding to a peak value of correlation values as a first displacement coordinate; generating a third descrambling sequence according to the first displacement coordinate; descrambling the odd sequence and the third descrambling sequence, subjecting the odd sequence, the third descrambling sequence and the secondary original sequence to circular correlation, and recording a coordinate corresponding to a peak value of correlation values as a second displacement coordinate; and obtaining a cell ID group serial number and frame starting information according to the first displacement coordinate and the second displacement coordinate. According to the TDD-LTE downlink synchronizing method, m<0> and m<1> can be determined only by performing 31 times of cross-correlation calculation with the length of 31, so that TDD-LTE downlink synchronization information is obtained, and the calculation amount is greatly reduced.