GESTRA - Recent Progress, Mode Design and Signal Processing

IEEE Signal Process. Lett.

Vehmas

2021

Target masking due to high sidelobes in the range-Doppler domain is a common problem in radar signal processing. Masking occurs when there is large variation in targets' signal-tonoise-ratio levels, caused by differences in either range or radar cross section. In this letter, we consider the design of a waveform to reduce the masking of far range targets caused by near range targets. Our method is based on a time-frequency concatenation of a Costas sequence with shifted parts of itself. It allows the user to design a low sidelobe region in the range-Doppler domain. Moreover, it approximately preserves the desirable uniform sidelobe level and thumbtack behavior of the Costas ambiguity function. We demonstrate a 20 dB sidelobe level reduction within the desired region compared to a normal Costas code with the same bandwidth and pulse length.

Section: Numerical Resultsmentioning

confidence: 99%

A Costas-Based Waveform for Local Range-Doppler Sidelobe Level Reduction

IEEE Signal Process. Lett.

Vehmas

2021

“…The simulative study also serves as a walk-through on constructing and using the proposed design tool. The last part demonstrates the use of the design tool in a space surveillance scenario, inspired by the novel GESTRA system (see [6], [7]).…”

Section: Numerical Resultsmentioning

confidence: 99%

“…To achieve this, we carried out empirical numerical simulations based on the ML estimator with the underlying signal model as described in (4). To avoid any undesirable numerical errors, we used a sequential brute force optimization on a grid with decreasing spacing to locate the ML maximum according to (7). For each combination of the setup parameters and design DOAs, the simulation was repeated N M C = 100 times with a different white Gaussian noise (WGN) realization to allow sufficient statistical accuracy.…”

Section: F Monte Carlo Simulationsmentioning

confidence: 99%

“…In estimating the target position, direction-ofarrival (DOA) estimation plays a crucial role. Emerging systems, such as the German Experimental Space Surveillance and Tracking Radar (GESTRA), whose purpose is to detect and track space debris [6], [7], consist of a large number of antenna elements to provide sensitive target detection and accurate DOA estimation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dimension-Reduced Rx Beamforming Optimized for Simultaneous Detection and Estimation

IEEE Trans. Aerosp. Electron. Syst.

Vehmas²,

Ender

2021

Phased array radar systems are indispensable in many applications requiring robust sensing of the environment. To achieve sensitive target detection and accurate direction-ofarrival (DOA) estimation, a high number of receiving antenna elements is needed. The high dimension of the element level data inevitably leads to a large computational burden for the digital signal processing. This problem can be overcome by transforming the element level data into a lower dimensional beamspace. In this paper, we present a novel parameter-controlled design method to construct this transformation. If the dimension reduction is not too drastic, it jointly achieves optimal detection and DOA estimation performance. Otherwise, it meets pre-defined performance criteria by exploiting an acceptable trade-off between detection and DOA estimation performance. We propose a general design tool, which is not limited to a specific array configuration. The design tool comprises a pre-calculated set of plots, providing the radar designer an overview of possible performance for a given scenario. We describe a straightforward method to construct the corresponding transformation. Numerical studies highlight the superiority of the proposed design method.

“…Lastly, we note that for the GESTRA parameters, the range walk for a LEO target can be very accurately compensated using keystone formatting or back-projection [22]. As an example, the worst-case Doppler mismatch ∆f d corresponds to a residual range walk of about one meter during a CPI of M = 24 pulses, which is negligible when compared with the range resolution ∆R ≈ 75 m. For this reason, range walk is omitted from the simulations.…”

Section: B Performance Metricsmentioning

confidence: 99%

Range Sidelobe Level Reduction With a Train of Diverse LFM Pulses

IEEE Trans. Aerosp. Electron. Syst.

Vehmas²

2022

Target masking is a pervasive problem in radar signal processing: the range sidelobes of the waveform's matched filter response may cause a strong target to prevent the detection of nearby weaker targets. Common solutions to sidelobe level reduction for frequency modulated waveforms result in an SNR loss. In this correspondence, we propose a novel method using pulse diversity to reduce the range sidelobes while avoiding SNR loss. The proposed approach is based on shaping the power spectrum of the summation of a train of constant-amplitude linearly frequency modulated pulses to resemble a Gaussian function. We present a numerical example demonstrating a drastic sidelobe level reduction. Importantly, our approach avoids any processing SNR loss.