# Multi-Frequency Target Detection Techniques for DVB-T Based Passive Radar Sensors
## 7 Conclusions  
Appropriate MF techniques for target detection have been proposed in this paper for the case of a DVB-T-based PR sensor. Aiming at jointly exploiting the signals emitted by the same DVB-T transmitter on multiple carrier frequencies, the approaches presented in [23] have been properly modified and extended to be effective in the newly considered application.  
Different non-coherent integration schemes have been considered, namely the centralized MF detection scheme and the decentralized MF detection scheme L/N. A detailed discussion of the required modifications that make them suitable for the exploitation of DVB-T broadcast transmissions has been presented. Specifically, the first modification concerned the selection of the integration time across the different frequency channels in order to obtain CAF maps directly comparable in the velocity dimension (namely, with the same velocity spacing). Furthermore, for the decentralized integration approach, a range resolution degradation has been proposed to counteract a possible range displacement of the target echoes received at different DVB-T channels. A preliminary performance comparison has been first carried on by means of simulations for specific case studies. Finally, the proposed MF integration schemes have been extensively compared against experimental data pertaining to aerial and maritime surveillance applications.  
The obtained results clearly showed that the MF approaches yield a significant enhancement of the target detection capability of the PR sensor with respect to the SF operation. This improvement is not only related to the expected enhancement of the target echo resulting from the non-coherent integration. In fact, all the proposed MF integration schemes have been shown to also guarantee a better control of the false alarm rate thanks to their capability to average the characteristics of the channels simultaneously employed.  
Among the proposed approaches, the centralized integration (operating with three or four DVB-T channels) typically yields the best performance in terms of target detection; in fact it always allows one to significantly increase the number of correct detections with respect to the best performing channel. Comparatively, the decentralized 2/4 approach yields only a slight loss in terms of target detection performance but provides the additional capability to mitigate the problems arising from the possible presence of ghost targets or unwanted plot formations (that are instead present in the centralized case). Therefore, based on the reported results, the decentralized integration scheme can be regarded as a practical solution in the considered applications if the target detection capability can be partly traded for a higher robustness to such problems.  
[PERSON] and [PERSON] designed and implemented the algorithms, analyzed the experimental results and wrote the paper. [PERSON] performed the setting of the experimental receiver, the acquisition campaigns and provided feedbacks on the implemented algorithms. The research activity reported in this paper was carried on within a research collaboration between Leonardo-Finnecancia S.p.A. and the DIET Dept. of Sapienza University of Rome. [PERSON] was the scientific coordinator on DIET side. [PERSON] supervised the research activity on Leonardo side and gave the technical support.  
The authors declare no conflict of interest.