25 research outputs found
Suppression approach to main-beam deceptive jamming in FDA-MIMO radar using nonhomogeneous sample detection
Suppressing the main-beam deceptive jamming in traditional radar systems is challenging. Furthermore, the observations corrupted by false targets generated by smart deceptive jammers, which are not independent and identically distributed because of the pseudo-random time delay. This in turn complicates the task of jamming suppression. In this paper, a new main-beam deceptive jamming suppression approach is proposed, using nonhomogeneous sample detection in the frequency diverse array-multiple-input and multiple-output radar with non-perfectly orthogonal waveforms. First, according to the time delay or range difference, the true and false targets are discriminated in the joint transmit-receive spatial frequency domain. Subsequently, due to the range mismatch, the false targets are suppressed through a transmit-receive 2-D matched filter. In particular, in order to obtain the jamming-plus-noise covariance matrix with high accuracy, a nonhomogeneous sample detection method is developed. Simulation results are provided to demonstrate the detection performance of the proposed approach
Coherent FDA Receiver and Joint Range-Space-Time Processing
When a target is masked by mainlobe clutter with the same Doppler frequency,
it is difficult for conventional airborne radars to determine whether a target
is present in a given observation using regular space-time adaptive processing
techniques. Different from phased-array and multiple-input multiple-output
(MIMO) arrays, frequency diverse arrays (FDAs) employ frequency offsets across
the array elements, delivering additional range-controllable degrees of
freedom, potentially enabling suppression for this kind of clutter. However,
the reception of coherent FDA systems employing small frequency offsets and
achieving high transmit gain can be further improved. To this end, this work
proposes an coherent airborne FDA radar receiver that explores the
orthogonality of echo signals in the Doppler domain, allowing a joint
space-time processing module to be deployed to separate the aliased returns.
The resulting range-space-time adaptive processing allows for a preferable
detection performance for coherent airborne FDA radars as compared to current
alternative techniques.Comment: 11 pages, 9 figure
Time-Range FDA Beampattern Characteristics
Current literature show that frequency diverse arrays (FDAs) are able of
producing range-angle-dependent and time-variant transmit beampatterns, but the
resulting time and range dependencies and their characteristics are still not
well understood. This paper examines the FDA transmission model and the model
for the FDA array factor, considering their time-range relationship. We develop
two novel FDA transmit beampatterns, both yielding the auto-scanning capability
of the FDA transmit beams. The scan speed, scan volume, and initial mainlobe
direction of the beams are also analyzed. In addition, the equivalent
conditions for the FDA integral transmit beampattern and the multiple-input
multiple-output (MIMO) beampattern are investigated. Various numerical
simulations illustrate the auto-scanning property of the FDA beampattern and
the proposed equivalent relationship with the MIMO beampattern, providing the
basis for an improved understanding and design of the FDA transmit beampattern.Comment: 10 pages, 9 figure
Three-Dimensional Target Localization and Cramér-Rao Bound for Two-Dimensional OFDM-MIMO Radar
Target localization using a frequency diversity multiple-input multiple-output (MIMO) system is one of the hottest research directions in the radar society. In this paper, three-dimensional (3D) target localization is considered for two-dimensional MIMO radar with orthogonal frequency division multiplexing linear frequency modulated (OFDM-LFM) waveforms. To realize joint estimation for range and angle in azimuth and elevation, the range-angle-dependent beam pattern with high range resolution is produced by the OFDM-LFM waveform. Then, the 3D target localization proposal is presented and the corresponding closed-form expressions of Cramér-Rao bound (CRB) are derived. Furthermore, for mitigating the coupling of angle and range and further improving the estimation precision, a CRB optimization method is proposed. Different from the existing methods of FDA-based radar, the proposed method can provide higher range estimation because of multiple transmitted frequency bands. Numerical simulation results are provided to demonstrate the effectiveness of the proposed approach and its improved performance of target localization