Transmitters' locations are usually assumed to be known in passive radars that exploit the third-party radio sources as illuminators of opportunity to detect targets of interest. However, there are such cases where transmitters' locations are unavailable in advance, causing difficulties for target localization. To address the problem, this paper investigates a novel transmitter localization method that combines the decoded automatic dependent surveillance-broadcast (ADS-B) information and passive radar measurement information. The localization model is established at the first, followed by the discussion of localization uniqueness and accuracy. The feasibility of the proposed method is further verified by numerical analyses.
The receiver and transmitter polarisations (RTPs) have great influence on detection performance in multi‐FM‐based passive radar. As the transmitter polarisation is uncontrollable in passive radar, the purpose of this study is to determine the appropriate receiver polarisation of the surveillance channel. Firstly, the impact of polarisation on radar detection performance is discussed from three aspects. Then, the probability of detection is used as a metric to select the better RTPs. Theoretical results show that, when most of the transmitted signals in the working band are vertically polarised, the horizontally polarised receiver can obtain better detection performance than the vertically polarised one. Finally, theoretical results are confirmed by field experiments.
In this letter, we use the known pseudorandom noise (PN) signal in the digital television terrestrial multimedia broadcasting (DTMB) system as a new illuminator of opportunity for the passive radar. We propose a computationally efficient signal processing method for the PN-based passive radar (PNPR). The proposed method takes advantage of the distinctive structure of the PN signal and constructs a locally remapped PN signal. The circular cross-correlation between the remapped PN signal and the original PN signal is an ideal impulse function. Thus, the PNPR even does not need to do the clutter cancellation. The proposed method is validated via both the simulated and experimental data.
Digital television signals are attractive illuminations of opportunity for the passive radars in the field of low altitude and slow speed target detection. The digital television standard permits reconstruction of a reference signal using the received signal in surveillance channel, which enables a single-antenna digital television based passive radar (SDPR) processing. This paper investigates the practical feasibility of a multistatic SDPR (MSDPR) for the drone detection. First, the detection range of the SDPR is analyzed in terms of signal processing procedures involving multipath energy, extracted reference signal purity, and receiving antenna. Second, according to the characteristics of the SDPR, the reference signal extraction is analyzed. In addition, considering that the SDPR cannot locate and track the detected target, a novel MSDPR processing method is proposed. The core idea of this method is to use the optimal reference signal extracted from the receiving station with the least interference as the shared reference signal in MSDPR, which can greatly improve the system detection capability. Finally, the small drone detection experiments using the MSDPR are presented. The theoretical considerations are demonstrated using the experimental data.
In frequency-modulation (FM)-based passive radar, the strong side peaks randomly appearing in the ambiguity function will generate a false alarm of target detection. To mitigate this side peak interference, this paper starts with a detailed analysis of the structure and ambiguity function of FM stereo signal. Then, it expounds the formation and characteristics of side peaks, together with a side peak identification method, which identifies and discards the false detections of the same range and Doppler caused by side peaks, respectively. The performance analysis, conducted using both simulated data and real recorded datasets, proves that the proposed method can eliminate the false targets caused by side peaks thus improving the detection performance in FM-passive radar.
Continuation power flow (CPF) is the most commonly used voltage stability static analysis method, and it consists of four steps: prediction, step-size control, parameterization and correction, among which parameterization is a key factor to ensure the success of continuous power flow calculation. At first, a performance analysis of common parameterization methods is studied, the criterion for judging the merits of the parameterization method is the distance between the predicted point and the exact solution of the CPF. The closer, the faster the correction can be converged. Various parameterization methods varies in merits and demerits in the different regions of the CPF solution curve. Therefore, in order to fully exploit, use and complement the information of each parameterization method, a coordinated combination of parameterization method is proposed. Varies of the parameterization methods are adopted in different regions of PV curve, while also setting parametric switching breakpoints during the process of tracing PV curve, and using the divergence of correction as the combination switching criterion. Finally, applying fixed-step method and classic variable-step method, continuation power flow calculations are carried out respectively with different parameters. Computational analysis of the IEEE 39-bus shows that the proposed coordinated combination parameterization method has significant effectiveness and superiority.
This study examines target detection in passive bistatic radar (PBR) using orthogonal frequency division multiplex (OFDM) signals. Most of the existing methods focus on multipath clutter cancellation prior to matched filter, which usually lead to intensive computational load. However, the detection methods exploiting the distinguished characteristics of OFDM signals have been studied much less. The published OFDM‐specific methods have opened up the new possibility of target detection without multipath clutter cancellation, whereas having detrimental effects on the floor level of cross ambiguity surface because of the inter‐symbol interference (ISI) and inter‐carrier interference (ICI). A novel OFDM‐specific method is proposed herein to feasibly extract the weak target echoes against the strong multipath clutter by low‐complexity suppression of the Doppler sidelobes resulting from the ISI and ICI. The simulated and experimental results following the robustness analysis validate the effectiveness of the proposed method, which provides a valuable basis for real‐time signal processing in PBR.
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