Dual-source jamming is an effective way to prevent monopulse radar systems from performing accurate angle measurements. In this investigation, based on noncoherent dual-source jamming, we propose a cooperative deception approach, which has the benefit of causing persistent and large angular measurement errors to protect a true target and therefore can greatly reduce the discrimination capability of a distributed track-to-track radar fusion system. A scenario involving a single target accompanied by a digital radio frequency memory (DRFM)-based repeater jammer countering two radar systems is illustrated. By controlling the amplitude ratio and time delay in a statistical manner, the active decoy signal and target echo signal can form a noncoherent angular glint effect and result in the deviation of the angle tracking loop of the two radar systems from the true target in opposite directions. The track-to-track association distance related to the retransmission parameters is explicitly derived, and its statistical characteristics are analyzed in detail. Simulations verify the feasibility of the approach. The advantage of the approach lies in its ability to destroy the so-called ''common origin'' signature of the physical target by injecting false angular information. The direct result is that the true target might not successfully complete the process of track-to-track association, thereby enabling us to realize the desirable effect of ''disguise the true target and instead show false decoys''. INDEX TERMS Dual-source jamming, networked radar system, radar countermeasures, radar tracking, track-to-track fusion.

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A track-before-detect (TBD) algorithm based on elliptical Hough transform (EHT) is presented for jointly detecting and tracking weak ballistic targets during its exoatmospheric flight. The new method makes use of the fact that the ballistic target follows the elliptical orbit when restricted to two-body problem. The relationship between raw radar measurements in the data space and the elliptical parameters in the parameter space is established with coordinate transformations. The EHT detection algorithm is designed and the orbit planarity is also considered to reduce the noise accumulation effect. The detection performances related to primary and second thresholds and signal-to-noise ratio (SNR) are analyzed and verified through simulations. The advantage of the new method lies in it can not only detect and track weak ballistic targets but also can predict the impact point by using available parameters.

An elliptical Hough transform (EHT) algorithm is proposed in the framework of track-before-detect (TBD) for joint detection and tracking of weak exoatmospheric targets. The new approach exploits the fact that when restricted to a two-body problem, the exoatmospheric target often follows an elliptical orbit, and thus the Hough transform integrated with orbital geometry information would have better detection performance. The relationship between the original radar measurements in data space and the elliptical parameters in parameter space is explicitly derived with multiple steps of coordinate transformation. It is found that the data points mapping into the parameter space essentially represent a quartic curve. An EHT-based algorithm is then designed, and orbit planarity is also taken into account to reduce the effect of noise accumulation. The influences of primary and secondary thresholds and the signal-to-noise ratio (SNR) on the detection performance are compared by simulations. Additionally, a real radar tracking dataset from a scientific satellite on 28 May 2017 is used to investigate the efficiency of the method. By adding some imaginary clutter to the raw orbit, the results indicate that it is very effective in detecting the real satellite trajectory in a low signal-to-noise ratio (SNR) environment. The advantage of the new method lies in it can not only simultaneously detect and track weak exoatmospheric targets but also can predict the trajectory by using these available detected parameters.