Digital beam forming method for multi-carrier broadband signal

Abstract

The invention discloses a digital beam forming method for a multi-carrier broadband signal. On the basis of a multi-phase processing technology, a sub-carrier DDS is designed in an FPGA; double accumulators and a register generate a P4 complementary code encoding phase in a delay manner; a compensation phase and a time delay are calculated according to a serial number of a sub carrier radio-frequency signal transmitting antenna unit; a phase code and a sub carrier baseband signal after phase compensation are generated based on a CORDIC algorithm by using the accumulator; digital delay, digitalup-conversion, digital-to-analog conversion, and intermediate-frequency filtering are carried out to output an analog subcarrier intermediate-frequency signal; a frequency-agility local-oscillator signal is generated by using an externally inputted reference clock signal, mixing and filtering are carried out on all sub carrier intermediate-frequency signals and the frequency-agility local-oscillator signal to generate sub carrier radio-frequency signals, power amplification is carried out and the processed signals are transmitted by antenna units; and the sub carrier radio-frequency signals transmitted by all antenna units are synthesized into a multi-carrier broadband signal in space. According to the invention, with phase control and continuously variable digital delay control, digitalbeam forming of the multi-carrier signal is realized.

Description

technical field [0001] The invention relates to a digital beamforming method for multi-carrier broadband signals, in particular to a digital beamforming method for multi-carrier signals based on continuously variable digital delay and phase compensation, and belongs to the technical field of array signal processing. Background technique [0002] Existing phased array radars use single-carrier-modulated waveforms (such as frequency modulation or phase-coded signals) for search, tracking, imaging, and other modes. Different modes use waveforms with different resolutions; they are subject to platform space, stealth, payload, electromagnetic compatibility, etc. Restricted by factors, several modes of phased array radar multi-target guidance and target detection often use the same array antenna, multiple modes use antennas in time-sharing, and radar time resources are dynamically allocated among several modes according to time slots. In the case of search and multi-target trackin...

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Problems solved by technology

[0003] In recent years, the multi-carrier phase coding (MCPC) signal or orthogonal frequency division multiplexing (OFDM) signal, which has been widely studied by the radar community in the world, has the characteristics of both narrowband signal and wideband signal, and has high spectrum efficiency, frequency diversity, and time Diversity, wideband measurement, low probability of interception, short-time Doppler frequency measurement, etc. The radar adopts multi-carrier signals and can work in multiple modes at the same time based on frequency division multiplexing, which solves the shortage of time resources in multi-modes of multi-target search, tracking, imaging, and guidance However, the multi-carrier signal has a large peak-to-average envelope power ratio (PMEPR), so it cannot use high-efficiency saturated power amplifiers, nor can it use traditional digital beamforming technology , therefore, digital beamforming of multi-carrier signals becomes a bottleneck technology for radars using multi-carrier signals

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