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This paper proposes a corner reflector and Luneburg ball reflector group. The omnidirectional radar cross-sectional (RCS) distribution characteristics of a fighter are simulated using the sharp and smooth RCS distribution features of the corner and the Luneburg ball reflectors, respectively. A new type of Doppler signal generation principle is proposed to design a Doppler frequency simulator to transmit frequency signals by connecting in parallel with the metal layer of the corner reflector and the Luneburg sphere ball, and then transmit through their other end. The existing radar target aircraft cannot simulate the RCS and speed of the targets that are less than 0.005 m² by enhancing the echo intensity of the target location, which makes it impossible for the military to conduct practice drills and evaluate the effectiveness of the air defense systems. The experimental results show that the Doppler frequency simulator successfully simulates the target speed of 0-80 km/h and when the speed is greater than 20 km/h, the error of the simulation frequency is less than 1.5%. The proposed method can provide guidance and a theoretical basis for simulating the speed of various types of aircraft in future work. [ABSTRACT FROM AUTHOR]

In this paper a modified ESPRIT algorithm, which bases on time subspace (T-ESPRIT) and spatial subspace of estimate 2D-DOA (azimuth and elevation) of a radiated source, that can increase the estimation accuracy with low computational load is introduced. Using the algorithm, the planar array is divided into a multiple uniform sub-planar arrays with the common reference point, and the T-ESPRIT method is applied for each sub-array. Secondly, Doppler frequency shift (fd) resulted from the target movement is estimated using displacement invariance technique (DIT). Then, in order to increase the estimation accuracy; the estimated Doppler frequency is used to correct the DOAE values according to target movement. Moreover, the proposed algorithm is combined the refined T-ESPRIT method with time differential of arrival (TDOA) technique to calculate an optimum DOA. It is found that the estimated results are better than the traditional ESPRIT methods leading to the estimator performance enhancement. [ABSTRACT FROM AUTHOR]

Whenever more than one target exist, the most important problem is to associate associating the received signals to the correct targets. This problem appears for all multiple target applications such as multiple target tracking and it is known as "Data Association ". For frequency-based systems, Multiple-Input Multiple-Output (MIMO) configuration together with the frequency diversity of the system enable us to determine the number of moving targets by using the Doppler frequencies. These frequencies include all relevant information about the location, velocity and direction of the targets and hence, they can be used efficiently to estimate the unknown target parameters. [ABSTRACT FROM AUTHOR]

The estimation scheme for DS-CDMA systems includes a computationally efficient and easily implemented pilot filter on CDMA forward channel. For different mobile channel environments, the optimal coefficients of pilot filter can be selected from pre-calculated table of coefficients to implement adaptive channel estimation. The simulation results illustrate that CDMA systems using the proposed adaptive channel estimation scheme can achieve better BER performance than non-adaptive schemes. [ABSTRACT FROM AUTHOR]

To estimate the Doppler in mobile OFDM system, a novel technique based on the cycle preamble of OFDM symbols was proposed. By calculating the auto-correlation function of cycle preamble of OFDM symbol, the maximum value of Doppler frequency excursion is obtained. The simulation results in fading channel show that this method can estimate the Doppler precisely. It is simply implemented with the cyclic structure of OFDM symbols, and any other additive data and pilots need not be inserted into the common OFDM symbols. Thereby it is easy to be adapted in the existing OFDM system. [ABSTRACT FROM AUTHOR]