Karl Erik Olsen

Analysis of the performance of a multiband passive bistatic radar processing scheme

The bistatic radar has been revitalized over the last few years through the rapid development of the passive bistatic radar technology. Passive bistatic radar systems have unique properties, especially is time on target high compared to traditional radar systems, as well as the freedom in choosing from the available transmitters of opportunity. This paper will focus on how to take advantage of the latter of these two special properties in order to achieve better range resolution while maintaining the high coherent processing interval.

Range and Doppler walk in DVB-T based Passive Bistatic Radar

This paper analyzes the effects of range and Doppler walk for a Digital Video Broadcast — Terrestrial based Passive Bistatic Radar of both simulated and experimental data. Range and Doppler walk cause energy dispersal in the correlation, thus the coherent integration time is limited by the bistatic velocity and acceleration. A method using the readily available Doppler information to compensate for the range displacement during integration due to non-zero bistatic velocity of target is described. By compensating and non-coherently adding several coherently processed intervals, the target signal to noise ratio is increased.

Performance of a multiband passive bistatic radar processing scheme-Part II

Simulations based on real-life FM radio waveforms showed that the algorithm is capable of improving range resolution, and thus the accuracy, according to theory for single scatterers as is summarized. The performance of the algorithm was impacted by the fluctuating behavior of the FM radio signal, although less than expected. The simulations also showed that two targets, not resolved in the individual channels, are resolved by using the proposed algorithm properly. Single scatterer targets may be significantly better positioned by the improved resolution (and as a consequence, also the accuracy) capabilities, i.e., 10 times the best performing individual channel.

Simultaneous use of multiple pseudo random noise codes in multistatic CW radar

In multistatic continuous wave radar, the choice of codes and frequencies used for transmission has a strong influence on detection and ease of parameter extraction. The paper describes the various effects of using single and multiple codes in a number of separated transmitters, either with the same or separated carrier frequencies. To visualize some of the results, synthetic radar data have been generated and used in the processing.

Hovering helicopter measured by bi-/multistatic CW radar

The use of bi-/multistatic radar to detect and extract parameters for classification of a hovering helicopter has been studied. An experimental continuous wave bistatic radar has been used in a series of measurements covering a range of bistatic geometries. Variations in detection of rotor tip velocity, number of blades of main and tail rotor and direction of Doppler shift is observed. The use of a series of bistatic receiver pairs (multistatic radar) will increase the ability to extract characteristic parameters that would enhance classification.

Results from an experimental continuous wave low probability of intercept bistatic radar - the first steps toward multistatic radar

The Norwegian Defence Research Establishment (FFI) has developed an experimental continuous wave (CW) low probability of intercept (LPI) bistatic radar. The radar is transmitting a CW binary phase coded signal at a maximum power of 1 W. The radar has been used to detect different targets in various trials. Selected results are presented, and future work is indicated.

Multiband passive bistatic DVB-T radar range resolution improvements and implications

The bistatic radar has been revitalized over the last few years through the rapid development of the passive bistatic radar technology. Passive bistatic radar systems have unique properties, especially is time on target high compared to traditional radar systems, as well as the freedom in choosing from the available transmitters of opportunity. This paper will focus on how to take advantage of the latter of these special properties in order to achieve better range resolution while maintaining the high coherent processing interval. Results from a real life target of opportunity will be presented.

Coherent range and Doppler-walk compensation in PBR applications

The focus of PBR research has shifted from FM to also include DVB-T and DAB over the last years, and are facing the challenges of higher bandwidth, i.e. improved range resolution. While the FM based PBR systems primarily had to deal with Doppler migration, the DVB-T based PBR systems are using CPIs which, combined with the higher bandwidth, leads to range and Doppler walk. The Doppler resolution is inversely proportional to the CPI, and longer CPI will therefore lead to finer Doppler resolution. And thus the higher bandwidth and longer CPI leads to increased propability of both range and Doppler walk. This paper describes a method to coherently compensate for both range and Doppler walk of targets already detected. The method coherently compensates both the translational movement and non-linear phase caused by range and Doppler walk.

X-band measurements of radar signatures of large sea birds

X-band measurements of flying sea birds have been carried out in order to investigate the potential of extracting features for target recognition from micro-Doppler signatures. More specifically, the contribution from wings to the birds total RCS is examined. This is important as these signatures are believed to be highly dependent on aspect angle and polarization. The underlying question is if the contribution from flapping wings in terms of backscattered power is large enough to be detected at all aspect angles. As modern surveillance radar systems will have increased sensitivity compared to their predecessors, more birds are expected be detected. So what SNR would be required to not only detect, but extract recognizable features from micro-Doppler signatures at any aspect angle as well?

Formation of Range-Doppler Maps Based on Sparse Reconstruction

This paper presents an application of compressed sensing in a pulsed system, such as a radar or sonar to form range-Doppler maps. Instead of transmitting a train of pulses, we portrait a system where the pulse emission itself takes place in a sparse manner. We show that any empty data segments can effectively be filled in by sparse reconstruction, which can also be used to extrapolate supplementary values. Simulations covering various conditions are used to demonstrate the effectiveness of the proposed setup.