Parameter Estimation of SAR Signal Based on SVD for the Nyquist Folding Receiver

Abstract

The Nyquist Folding Receiver (NYFR) is a novel ultra-wideband (UWB) receiver structure that can realize wideband signal monitoring with fewer components. The NYFR induces a Nyquist zone (NZ)-dependent sinusoidal frequency modulation (SFM) by a modulated local oscillator (LOS), and the intercepted linear frequency modulated (LFM) synthetic aperture radar (SAR) signal will be converted into an LFM/SFM hybrid modulated signal. In this paper, a parameter estimation algorithm is proposed for the complicated NYFR output signal. According to the NYFR prior information, a chirp singular value ratio (CSVR) spectrum method based on singular value decomposition (SVD) is proposed to estimate the chirp rate directly before estimating the NZ index. Then, a fast search algorithm based on golden section method for the CSVR spectrum is analyzed, which can obviously reduce the computational complexity. The simulation shows that the presented algorithm can accurately estimate the parameters of the LFM/SFM hybrid modulated output signal by the NYFR.

An improved local oscillator modulation of modulated sampling scheme for multiple mono-pulse radar signals reconstruction

“…Under this condition, all folded signals in the 0th NZ have the same carrier frequencies, and the folded carrier frequencies are assumed as (12) can be rewritten as According to (13), the element of , y in the kth NZ can be computed as where * is the convolution. Since the DFT result is the spectrum discretization of the discrete-time Fourier transform (DTFT), the DTFT result is employed to approximate the DFT result in (14) to simplify the analysis. Besides, the impact of the window function on the signal e 2jπ f ci mT ADC is omitted to further simplify the analysis of ( 14).…”

“…Compared with random sampling scheme or the modulated wideband converter (MWC) using multiple clocks [7], the modulated sampling scheme only requires a single channel to achieve wideband receiving and it preserves the signal structure [12], which means the receiving resource of the modulated sampling scheme is low and its output can be processed easier. Based on the modulated sampling scheme, the improved NYFR structures, the output characteristics and the corresponding signal processing are investigated [13][14][15][16][17]. The modulated sampling scheme uses a non-uniform modulated radio frequency (RF) sampling to realize wideband receiving.…”

Wideband spectrum sensing using step-sampling based on the multi-path nyquist folding receiver

“…The sparse signal reconstruction via CS-based methods or other optimization methods has high computational and complexity [21]. And there are high signal-tonoise (SNR) requirements for the information acquisition [22]. Meanwhile, the inherent bandwidth broadening characteristics of the NYFR outputs could potentially lead to a miss of some weak signals due to the folded noise and harmonics [23].…”

Parameter estimation of frequency shift keying radar signal intercepted by Nyquist folding receiver using periodic linear frequency modulation local oscillator

“…In addition, the photonic NYFR structure [10] and the NYFR output noise properties [11] are investigated. In terms of processing the radar signal intercepted by the NYFR, the mono-pulse radar signal, the binary phase coded signal, the linear frequency modulation signal and the hybrid modulation radar signal are investigated [12][13][14][15][16]. However, for the FSK radar signal intercepted by the NYFR, there are only a few studies in the literature.…”