Multistatic coherent MIMO radar networks

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Radar networks represent a consistent further development of existing radar systems in which the performance of the overall system can be increased by networking several radar nodes. Due to the additional paths between the target and the radar nodes compared to the single sensor, targets can be resolved better, e.g. due to the additional bistatic viewing angle of several radars and due to the additional phase information of several radar nodes, which span a large aperture in coherent operation. A novel approach of a radar network, which was the focus of the predecessor project, results when additional network nodes are implemented as repeater elements in addition to the radar sensors, which are not designed for signal processing but only amplify incident signals, modulate them via a mixer and retransmit them. In the project carried out, significant advantages of coherent radar repeater networks over single sensors were demonstrated. For this purpose, a system concept for the function of the repeater networks was developed as well as a signal processing chain that includes calibration and compensation of near-field effects. The high angular separation capability of the repeater networks and the good SNR when using the triangular paths were demonstrated. For the repeater networks, the main drawback has been shown to be that the networks are not arbitrarily scalable due to the large increase in the required baseband widths caused by the modulation of the repeater signals and the non-ideal characteristics of the repeaters. In order to circumvent these weaknesses of the repeater approaches, multi-channel digital receiver units are to be used instead of repeaters in the follow-up project now applied for. In this context, a digital receiver unit is understood to be a radar receiver - as in the case of a digital radar - in which the entire high-frequency band is shifted to the baseband by analog mixing and digitized there. Consequently, the network then consists of at least one analog chirp sequence MIMO radar and one or more digital receiver units. Like the repeater networks, these mixed analog-digital radar networks promise to enable the construction of coherent networks without cable connections of the network nodes. Compared to the repeater networks, however, there is the advantage that the analog-digital networks are also scalable to a large number of nodes and, due to multi-channel operation, enable virtual MIMO apertures that are significantly more fully occupied than when using a repeater.