38 results about "Non data aided" patented technology

A hybrid carrier frequency offset estimator that uses data-aided and non-data-aided signal processing techniques to produce multiple candidates for the carrier frequency offset within a return channel receiver in a DVB-RCS system using turbo coding and quadrature phase shift keying (QPSK) data modulation. In this system, the invention is employed to estimate signal distortion caused by carrier frequency offset so that this particular source of signal distortion can be removed to improve the ability of the receiver to maintain synchronization in low signal-to-noise conditions. This, in turn, allows the receiver to meet the DVB-RCS performance target, measured in terms of packet loss ratio, in low signal-to-noise ratio conditions and in particular for burst-mode data transmission with a short data packet size.

A class of non data-aided cyclic based robust estimators for frequency offset estimation of multi-carrier systems is disclosed. The use of sufficient statistics provides a minimum variance unbiased (MVU) estimate of the frequency offset under complete knowledge of timing offset error. The Neyman-Fisher factorization theorem and Rao-Blackwell-Lehmann-Scheffe theorem are used to identify the sufficient statistic and appropriate mapping functions. It is shown that there is but one function of the sufficient statistics which results in the minimum variance estimate among the possible class of cyclic-based estimators. Also, a moment estimator of frequency offset is provided to obtain a consistent estimate of carrier offset under uncertain symbol timing error. The moment estimator does not rely on any probabilistic assumptions. Thus, its performance is insensitive to the distribution of the additive noise. A unified structure characterizing both the MVU and moment estimators, as well as a maximum likelihood estimator of a related, copending application is disclosed.

The present disclosure is directed at a method and apparatus for generating a metric for use in any one or more of lock detection, SNR estimation, and modulation classification. To generate the metric, an input angle in the form of a symbol phase or a difference in symbol phases is used to evaluate a base function. The base function relates possible metrics to possible input angles using a triangle wave having its maxima or minima at ideal input angles, and the other of its maxima or minima at angles midway the ideal input angles. Described are embodiments that are one or more of non-data aided; that may be implemented relatively efficiently in hardware; that can function using one sample / symbol; that can achieve relatively good detection certainty using relatively few estimates; and that can be used to implement modulation classifiers, lock detectors, and SNR estimators that are resilient to imperfections in automatic gain control.

The present invention provides systems and methods for enabling a navigation signal receiver to perform both data assisted and non-data assisted integration to provide better integration during signal acquisition, reacquisition and tracking. In data assisted integration mode, a receiver uses known or predicted data bits to remove the modulated data bits of a received signal prior to integration. In non data assisted integration mode, when the data bits are not known or predictable, the receiver uses an optimal estimation or maximum likelihood algorithm to determine the polarities of the modulated data bits of the received signal. This may be done by determining which of various possible bit pattern yields the maximum integrated power. When the modulated data bits are not known or predictable over a limited range, the receiver carries out data assisted integration over the known or predictable data bits and additional non data assisted integration.

The present invention relates to the communication field, in particular to a frequency synchronization method and device. A frequency synchronization method, comprising: extracting a burst header from a burst signal; performing frequency offset estimation and phase offset estimation on the burst header; using the frequency offset estimation to perform frequency offset compensation on the received burst signal , using the phase deviation estimation to perform phase deviation compensation on the received burst signal; extracting a unique word from the phase deviation compensated burst signal; using the unique word to perform phase ambiguity on the phase compensated burst signal Eliminate and perform frequency synchronization. A frequency synchronization device includes: a first extraction module, an estimation module, a first compensation module, a second extraction module and a processing module. Through the present invention, the non-data-assisted method is used to estimate the frequency and phase deviation without using unique characters, which solves the problem of low estimation accuracy when the number of unique characters is small.

The invention discloses a non-data auxiliary SNR estimation method for open loop and closed loop combined MPSK signals. The method includes the first step of obtaining second-order envelope statistical information and first-order envelope statistical information through two received orthogonal signals, the second step of utilizing the square of the sum of the second-order statistical information of first-section data and the square of the sum of the first-order statistical information of the first-section data to calculate a statistical parameter value, the third step of estimating the SNR according to the one-one mapping relation between the statistical parameter value and the SNR, and the fourth step of carrying out smoothing filtering on the SNR estimated value through a closed-loop filter. The method has the advantages that any auxiliary data are not needed, carrier recovery does not need to be carried out, the SNR estimated value can be fast obtained, the estimation accuracy is high, the estimation deviation is small, the requirements of data quantization in the hardware implementation process are fully considered, and the complexity of hardware implementation is low. The non-data auxiliary SNR estimation method for the open loop and closed loop combined MPSK signals is applied to a communication system using an MPSK constant envelop modulation mode and other modes.

The invention relates to a non-data aided phase noise blind estimation method for QAM signal, an M-th power algorithm based on improvement is provided, the algorithm can correct the frequency deviation and the phase deviation caused by the phase noise, a power estimation algorithm is adopted without any other data information for the frequency deviation and the phase deviation in the signal, a more precise output information is obtained through gradually correcting the estimation error, the estimation process is simplified, and the computation complexity is greatly reduced; according to the invention, in a condition that has no need to have the help of signal-to-noise ratio and auxiliary data information, the method represents good estimation performance, and a simple and efficient solution is provided for the high-speed wireless optical communication QAM signal phase estimation problem.