Parameter Estimation of LFM Signal Intercepted by Synchronous Nyquist Folding Receiver

Abstract

Abstract-Nyquist folding receiver (NYFR) is a new kind of interception architecture, which can simultaneously intercept wideband signals in multi-Nyquist zones with one or two analog-to-digital converters (ADCs). A parameter estimation algorithm of the linear frequency modulated (LFM) signal intercepted by an improved NYFR is presented. Firstly, the NYFR is improved by introducing a synchronous mechanism, and we denote this structure as a synchronous NYFR (SNYFR). Secondly, taking LFM as an example, the input and output noise distributions of an SNYFR are discussed. Then, a fast parameter estimation algorithm is derived from the frequency spectrum of the output signal, and an advice for the design of local oscillator signal is given. Simulations show that the parameter estimation accuracy is close to the maximum likelihood when the signal to noise ratio (SNR) is above −3 dB.

A parameter estimation algorithm for LFM/BPSK hybrid modulated signal intercepted by Nyquist folding receiver

“…1 , The NYFR uses zero crossing rising (ZCR) voltage time to control the radio frequency (RF) sample clock and generate the RF LOS p ( t ) which is a non-uniform sampling LOS with a certain modulation type. As long as the modulation information of the LOS remains unchanged, we can simplify the LOS as [ 8 ] where m ( t ) = 2 πf s t + θ LOS ( t ) + φ LOS , k is an integer, f s is the LOS carrier frequency which equals the value of NZ bandwidth when the input signal is complex, define (− f s /2, f s /2) as the 0th NZ, hence, ( kf s − f s /2, kf s + f s /2) is the k th NZ, θ LOS ( t ) is the LOS modulation, and φ LOS is the LOS initial phase.…”

“…Then, some new NYFR architectures using different local oscillator (LOS) modulation types have been proposed. Synchronous NYFR (SNYFR) structure using simplified LOS has been proposed and its output can be processed more easily because of the synchronous LOS [ 8 ]. Other LOS modulation types such as binary phase shift keying (BPSK) LOS and noise sequences are proposed [ 9 , 10 ], which can improve the performance of NYFR because the bandwidths of these LOS modulations remain unchanged.…”

“…The NYFR can realize wideband receiving with a small amount of equipment, but the information of LOS modulation will be added on its output [ 8 ], and its output will be more complex compared with the conventional receiver. Some conventional radar signals such as linear frequency modulation (LFM) signal and frequency agile (FA) signal intercepted by the NYFR have been investigated, and the parameter estimation methods using multi-channel structure have been proposed [ 8 , 11 ].…”

“…Because the LFM/BPSK signal intercepted by the NYFR contains the LOS modulation, it may be difficult to find a time-frequency kernel which is optimal for the NYFR output directly. In this paper, we will study this problem in another way and make full use of the NYFR prior information which is neglected in [ 8 ] and [ 11 ]. We will model the LFM/BPSK signal intercepted by the NYFR based on the signal self-characteristic and the NYFR prior information, and propose a parameter estimation algorithm which has different estimation steps compared with the existing NYFR output parameter estimation algorithm [ 8 , 11 ].…”

The RIP and block-RIP analysis of Nyquist folding receiver for recovering signals

“…Reference [ 1 ] discusses the CS framework of the NYFR and the signal reconstruction with single-frequency applying the orthogonal matching pursuit algorithm (OMP). References [ 8 ] and [ 9 ] regard the NYFR architecture as a modulated sampling scheme. They study the detection and parameter estimation algorithm of signal under the different types of the modulated signal.…”