Fault management based on systems description as directed graph with absolute dependence relations

A new systems description method that utilizes graph theory for systems modeling is presented. The new method represents the system in terms of a directed graph, where each system component is represented by a vertex and dependencies between system components are represented by directed edges, also called arcs. The absolute dependence rule is introduced as the criterion for the analysis of a system into the graph representation. Together with the concept of an elementary component of a system, the proposed systems description method is applicable to a wide variety of systems for fault diagnosis, reliability engineering and other system modeling and system architecture design purposes. The application of the new method for fault diagnosis is demonstrated in this paper by developing a novel fault management algorithm, and connections with several other systems description methods are presented

Compensation of range migration for cyclically Repetitive Doppler-Sensitive Waveform (OFDM)

Range migration, which occurs for targets with high velocity when the radar range resolution is high, is solved by exploiting the cyclically repetitive waveform-namely, orthogonal frequency division multiplexing. The proposed technique is based on a signal processing method that solves the Doppler ambiguity by exploiting the Doppler sensitivity of the multicarrier spread spectrum structure. The new method extends the availability of narrowband delay-Doppler processing to a wider range of waveform and target parameters

Utilization of laurent decomposition for CPM radar waveform design

CPM waveforms, having limited spectral spill, are considered viable as radar waveforms. Laurent Decomposition, which expresses the CPM waveform as the sum of PAM components, is investigated for CPM radar waveform design. Mismatched filter design results based on the Laurent decomposition and improved spectrum limitation associated with waveform generation based on PAM components are presented. Generating CPM waveform by utilizing PAM components inherently shapes pulse rising and falling edges and improves the spectrum roll-off significantly

Narrow band wide angle scanning circular frequency diverse array radar

One dimensional Linear Frequency Diverse Array (FDA) is extended to a circular two dimensional FDA array (CFDA). The CFDA operates as a pulsed FDA in the transmission (TX) mode while it operates as a pulsed phased array (PA) in the receiving (RX) mode. CFDA has a constant antenna pattern steering property in the plane of the circle while it has FDA scanning property in the orthogonal plane. This is achieved by assigning frequency offsets to the elements of the array cosinusoidally which changes with the steer angle, making the CFDA narrow band. The matched filter (MF) for pulse compression is also designed for a particular direction of interest

A method for measuring the radial velocity of a target with a Doppler radar

The method comprises a step of transmitting an OFDM waveform comprising several frequency carriers transmitted simultaneously, the frequency carriers being coded in order to improve the Doppler response. The method also comprises a step of receiving the waveform echoed from the target. The initial phase of each frequency carrier is recovered from the waveform echoed. The recovered initial phase of each frequency carrier is cyclically shifted in order to compensate for the Doppler effect and subsequently decoded. A compressed pulse is synthesized from the decoded initial phases

Multi-carrier radar waveform schemes for range and Doppler processing

A processing technique that utilizes the OFDM communication waveform as the radar waveform is considered. The double use of the waveform for communications and radar enables establishing radar networks communicating through the radar beam. The processing technique exploits the Doppler sensitivity of the OFDM to reduce the Doppler ambiguity. An enhancement to the waveform and the processing is proposed to completely eliminate the Doppler ambiguity

OFDM signals as the radar waveform to solve doppler ambiguity

The OFDM communication signal is proposed for spread spectrum radar signal generation. A radar signal processing technique is developed to solve the Doppler ambiguity in the pulsed Doppler radar by exploiting the multicarrier structure of the OFDM and the random phase modulation on the carriers in a Doppler compensation scheme. The novel processing technique is analyzed in detail, through both analytical derivations and Monte Carlo simulations, to demonstrate the feasibility of using the OFDM modulation with random phase coding for radar signals

Solving Doppler ambiguity by Doppler sensitive pulse compression using multi-carrier waveform

A processing technique, which exploits the structure of the multi-carrier signal to obtain range and radial velocity information from the echo signal, is proposed. The novel processing technique executes the Doppler matched filter bank digitally, and solves the ambiguity in the radial velocity measurements in one train of multi-carrier pulses as a result of Doppler sidelobes of the ambiguity function being lower. The processing technique, being independent of the phase coding on the multiple carriers, enables integration of communication and radar waveforms