The invention provides an FPGA-based multichannel airborne magnetometry data acquisition system, which is characterized by comprising a main control chip, optical pump magnetometers, three-axis magnetic flux gate sensors and a GPS satellite positioning module, wherein the main control chip adopts software to design an optical pump data acquisition module, a three-axis magnetic flux gate data acquisition module and a GPS positioning data acquisition module, and the three modules can parallelly acquire corresponding data. Magnetic field data of multiple optical pumps, the three-axis magnetic flux gate data and the GPS positioning data can be acquired in real time, storage and recording of all data can be realized, full-tensor airborne magnetometry can be realized, the change rate information of a geomagnetic vector in three-dimensional space is deeply analyzed, the integration is high, the magnetic field measurement precision is high, and strong supports are provided for geological structure research and mineral resource exploration.

FPGA-based multichannel airborne magnetometry data acquisition system

The invention relates to wireless communication channel testing methods based on frequency difference detection time domain compensation under asynchronous clocks and belongs to the field of wirelesscommunication. The method comprises the operation steps of 1, carrying out a training process, wherein the training process comprises the following steps that 1), under the condition that a standard channel does not comprise multipaths, a sending end sends a digital sequence; 2), a receiving end receives the digital sequence; 3), the receiving end analyzes and records frequency difference and phase difference under current asynchronous clocks according to the received digital sequence; and 2, carrying out a testing process, wherein the testing process comprises the following steps of 4), in atested environment, the sending end sends an m sequence; 5), the receiving end receives the m sequence and carries out quadrature demodulation on received signals to obtain I and Q sequences; 6), thefrequency difference and phase difference of the I and Q sequences in the testing process are compensated according to the frequency difference and the phase difference obtained through recording in the training process; and 7), the maximum testing result is output, so a wireless channel is detected. According to the methods, effective methods for wireless communication channel testing under the asynchronous clocks are provided, so relatively convenient channel testing is realized.

Wireless communication channel testing methods based on frequency difference detection time domain compensation under asynchronous clocks

The invention belongs to the technical field of wireless communication, and discloses an anti-phase noise blind carrier recovery method suitable for a high-order modulation mode. On the basis of a conventional decision-based extended Kalman carrier recovery algorithm suitable for low-order QAM modulation, a mode selection module used for selecting different frequency offset step and mean square error value calculation length parameters is added. Through the calculation of a mean square error value of symbols of different lengths before and after the decision, the frequency offset step parameters of the extended Kalman filter are adaptively selected, and so an extended Kalman filter algorithm can also take into account both large frequency offset acquisition performance and low steady-statejitter performance in a high-order modulation system. The carrier recovery algorithm of the invention is a blind carrier recovery algorithm, is proved to be capable of resisting phase noise by simulation verification, and is an algorithm suitable for the high-order modulation mode.

Anti-phase noise blind carrier recovery method suitable for high-order modulation mode

The invention discloses a communication device The device comprises an input end, an output end and an interference reducing module The interference reducing module is coupled between the input endand the output end The input end receives a data signal changing with time The interference reducing module obtains first partial data of the data signal at first time, and generates a first offsetresult and a second offset result according to the first partial data The interference reducing module obtains second partial data of the data signal at second time The interference reducing moduleselects one of the first offset result and the second offset result according to the second partial data to use the same as a selection result, and transmits the selection result to the output end

Communication device and communication method

The invention relates to the field of microwave communication, in particular to a carrier recovery method in high order modulation-demodulation. According to the method, carrier recovery is performed by inserting an auxiliary sequence and utilizing the correlation of the auxiliary sequence, and the method comprises the steps of extracting clocks, generating timing frames, recovering and compensating the frequency difference of received carriers and transmitted carriers, recovering and compensating the phase difference of the received carriers and the transmitted carriers, removing phase ambiguity, and the like. According to the method, the auxiliary sequence is utilized repeatedly to carry out correlation operation, computation of the frequency difference and the phase difference, and correlative compensation, so that the anti-interference ability is good, carrier phases can be reliably recovered under the condition of low signal to noise ratio for completing signal demodulation, and the robustness is high, and in addition, a symbol rate is adopted in a realization process, requirements on a dependent hardware platform are lower, and coding is simple to realize.

Carrier recovery method in high order modulation-demodulation

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Carrier recovery method in high order modulation-demodulation