Abstract
Sparse frequency agile orthogonal frequency division multiplexing (SFA-OFDM) signal brings excellent performance to electronic counter-countermeasures (ECCM) and reduces the complexity of the radar system. However, frequency agility makes coherent processing a much more challenging task for the radar, which leads to the discontinuity of the echo phase in a coherent processing interval (CPI), so the fast Fourier transform (FFT)-based method is no longer a valid way to complete the coherent integration. To overcome this problem, we proposed a novel scheme to estimate both super-resolution range and velocity. The subcarriers of each pulse are firstly synthesized in time domain. Then, the range and velocity estimations for the SFA-OFDM radar are regarded as the parameter estimations of a linear array. Finally, both the super-resolution range and velocity are obtained by exploiting the multiple signal classification (MUSIC) algorithm. Simulation results are provided to demonstrate the effectiveness of the proposed method.
Highlights
With the rapid development of electronic technology, orthogonal frequency division multiplexing (OFDM) technology has already been widely applied in communication systems [1,2,3]
The SFA-OFDM radar can be equivalent to the traditional frequency agile radar, i.e., each pulse is an linear frequency modulation (LFM) signal and the carrier frequencies are varied in a random manner [30]
To achieve the super-resolution range and velocity estimations simultaneously, a new signal processing scheme for the SFA-OFDM radar is investigated. It can effectively solve the problem of coherent integration caused by frequency agility
Summary
With the rapid development of electronic technology, orthogonal frequency division multiplexing (OFDM) technology has already been widely applied in communication systems [1,2,3]. A similar stepped-carrier OFDM-radar waveform is investigated in [14], which can simultaneously achieve the high-resolution range and velocity but with a much lower baseband bandwidth. In [23], a frequency-agile sparse OFDM radar with short sequences of narrowband pulses of different bandwidths is proposed, and the compressed sensing (CS) theory is applied to obtain a high-resolution range-velocity profile. Based on the previous work, the super-resolution range and velocity estimations for the sparse frequency agile OFDM (SFA-OFDM) radar is studied in this paper. Compared with the Doppler processing method proposed in [20], the proposed method solves the conflict between the frequency agility and coherent processing It can obtain the super-resolution range and velocity in a CPI.
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