A clean signal reconstruction approach for coherently combining multiple radars

Abstract

Distributed radars have the potential to combine coherently for achieving a high signal-to-noise ratio (SNR) while maintaining a moderate antenna size. The key to coherently combining multiple radars is obtaining accurate coherent parameters (CPs), which are used to adjust the transmitting/receiving time and phase of each radar. One approach for CP estimation is to transmit orthogonal waveforms. However, ideally, orthogonal waveforms occupying the same frequency band may not be found in practice. Cross-correlation energy leakage exists between non-orthogonal waveforms, which seriously impairs the accurate acquisition of CPs. To solve this problem, we propose a clean signal reconstruction approach for CP estimation. This approach reconstructs clean echoes by gradually stripping out the cross-correlation energy leakage with a reconstruction-elimination-reconstruction framework. And CPs are obtained from these reconstructed clean echoes. Since the majority of cross-correction energy leakages are eliminated, enhanced CP estimation performance can be achieved. Verified simulations are designed for a dual radar scenario. Results show that the proposed approach significantly improves the performance of CP estimation while reducing the SNR requirement for coherently combining multiple radars.

Dual‐radar coherently combining: generalised paradigm and verification example

“…In the same way, by choosing appropriate echo pairs, receive CPs can be also estimated. More detailed CPs estimation discussions and algorithms can be found in our previous work [11].…”

Structure‐based joint estimation algorithm for distributed coherent aperture radar

“…The correlation algorithm can obtain the time offset estimates by correlating the matched filtered signals. As its updated versions, some model‐based algorithms [1, 8] correlate the ‘cleaned’ matched filtered signals reconstructed by a specific model hence further improves its performance.…”

“…Recent years have witnessed an increasing interest in distributed coherent aperture radar [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. This new concept radar, consisting of several widely distributed small aperture radar units, is proposed to overcome some disadvantages of traditional large aperture radars, such as the inconvenience of transportation, expensive costs of building and so on.…”

“…Several papers addressed the system processing framework [1,[5][6][7] of the distributed coherent aperture radar and analysed the performance of coherence parameters estimation for it [13][14][15][16]. Some authors discussed the coherent processing algorithms [1,[8][9][10][11]. Assume there is only one target in the overlap section of multiple receiving beams from widely separated radar units.…”

“…Most existing methods [1,[8][9][10][11] of coherence parameter estimation obtain performance improvement of output SNR gain by refining the signal quality of the output signals from each radar unit separately. The performance of distributed coherent aperture depends seriously on the output SNRs of radar units.…”