Performance of a multiband passive bistatic radar processing scheme — Part I

The performance of a mathematical processing scheme has been presented. The algorithm is inspired by the HRR approaches used in HRR radar systems on how to exploit multiple nonadjacent broadcast channels or bands in the PBR range correlation to achieve higher range resolution while maintaining Doppler resolution from relatively long integration times. The broadcast channels or bands are assumed to be from a single transmitter. The following problems have been addressed and solved [26]-[28], [31]: By using broadcast signals at different carrier frequencies, the target Doppler shift is different, and the proposed method takes this into account. By using time-varying waveforms (signals of opportunity, i.e., FM, DAB, DVB-T, or pseudonoise) in the range correlation, a time-varying result is achieved. If this becomes an issue, it should be countered by increasing the range correlation time. This might be achieved either by increasing the total CPI or by keeping the CPI constant and reducing the Doppler resolution. Combining multiple bands results in cochannel correlation, as well as cross-channel correlation. While only the former is sought, it is shown that the cross terms may be neglected due to their correlation properties with respect to each other. This is also helped by their destructive frequency component from the demodulation. Even though good individual correlation performances are achieved for single channels or bands, summing the correlation contributions for the different channels or bands might cause an out-of-phase summation that modulates the range correlation peak in a way that may cause erroneous range estimates to be made. The algorithm estimates a phase correction term that, once applied, makes all contributions in phase; thus, erroneous range estimates, as well as destructive summing of target responses, are avoided.