Two helicopter classification methods with a high pulse repetition frequency radar

Abstract

In this study, two helicopter classification methods with a high pulse repetition frequency radar are proposed. By analysing the returned signal from a main rotor, the authors find that the essential difference between rotors appears when none of blades is orthogonal to the incident waves. Based on this difference, the authors propose two methods to classify the helicopter. The first one is based on the matched filters (MFs), including the time MF and the time-frequency MF. The second one derives from time-frequency masks. Experimental results demonstrate that both methods have the ability to classify helicopters with the same micro-Doppler parameters at a low signal-to-noise ratio. And they are robust against errors of the estimated parameters and the gesture of the helicopter.

Extraction of Doppler signature of micro‐to‐macro rotations/motions using continuous wave radar‐assisted measurement system

“…where N is the number of blades in the rotating structure. Typically, N is 2 for drone/UAV/quadcopter propeller and it varies from 2 to 6 for helicopters of different radar cross-section (RCS) and payload capacity [13,14,25]. More than one rotating target or a target having multiple rotating parts can be distinguished based on the micro-Doppler frequency and range profiles generated by them [13,26,27].…”

Aerial target classification based on feature analysis

“…In [5], bicoherence‐based features are extracted, which enables the classification of different aerial targets. For the classification of helicopter, two methods based on the time–frequency features analysis are proposed [6]. In [6], the m‐D characteristics are discussed in detail when the rotating parts are not orthogonal to the incident waves.…”

“…For the classification of helicopter, two methods based on the time–frequency features analysis are proposed [6]. In [6], the m‐D characteristics are discussed in detail when the rotating parts are not orthogonal to the incident waves. In [7], parameter‐estimating methods are used to yield the corresponding circular correlation coefficients so that the m‐D signatures of different targets can be recognised.…”

Micro‐Doppler of helicopter with different blade shapes

“…Introduction: By extracting the signatures from the micro-Doppler (m-D) of the main rotor such as the circle of the flashes and the bandwidth of the echo, a helicopter is classified and identified [1][2][3].…”

“…Assume that the distance between the radar and the rotation centre satisfies R 0 ≫ l P . For the main body of a blade, the echo is obtained as [2]…”