Multistatic Receivers Research Articles

Cognitive waveform and receiver selection mechanism for multistatic radar

Novel cognitive radar (CR) approach to improve the extended targets detection and resolution is developed in a multistatic radar context. A cognitive waveform selection mechanism based on target probability of detection maximisation in conjunction with adaptive receiver allocation/selection is proposed. Apart from the cognitive waveform selection objective, this process aims at evaluating the optimal positions for the radar receivers in an attempt to iteratively minimise the geometric dilution of precision, subsequently resulting in a high precision target geolocation estimate. The cognitive waveform selection mechanism is based on target dynamics involving time varying target scattering characteristics and clutter distribution parameters. Thus with the proposed dual objective approach, the concept of cognition can be extended to both the radar transmitter and receiver sites. Numerical results demonstrate better target detection performance and positioning accuracy using the proposed approach as compared with conventional methods based on static transmission or stationary multistatic receivers topology.

Multistatic performance prediction for Doppler-sensitive waveforms in a shallow-water environment

Navies worldwide are now operationally capable of exploiting multistatic sonar technology. One of the purported advantages of multistatics when detecting directional targets should be the increased probability of receiving a strong reflection at one of the multistatic receivers. However, it is not yet clear (or intuitive) how best to deploy multistatic-capable assets to achieve particular mission objectives. The Performance Assessment for Tactical Systems (PATS) software was recently developed by Maritime Way Scientific under contract to Defence Research and Development Canada as a research tool to assist in exploring different approaches to multistatic performance modelling. Beginning with a user-defined environment and sensor layout, PATS uses transmission loss and reverberation model results to calculate signal excess at each grid point in the model domain. Monte Carlo simulations using many realizations of target tracks allow for the calculation of the cumulative probability of detection as a means to assess performance. Results will be presented comparing the shallow-water performance of monostatic and multistatic sensors using frequency-modulated and Doppler-sensitive waveforms as well as omnidirectional and directional targets in a variety of realistic military scenarios.

Performance analysis of natural frequency‐based multiple radar target recognition for multiple‐input–multiple‐output radar application

In this study, the authors propose an analytic performance analysis applicable to the case that there are multiple radar responses from distinct radar targets at resonance frequency range. Multistatic radar can employ multiple receivers, which are usually located far away enough not to simultaneously receive the response from the same target. It is assumed that the authors receive returns from M distinct radar targets. In this study, they assume that each receiver receives only one target response, which is reasonable assumption for the multistatic receivers which are separated enough not to receive the same target response together. Using the projections of all the M target responses onto the column space associated with the specific k th radar target, they try to recognise which radar target response is from the k th radar. The derived expressions are validated by comparing the results obtained from the derived expressions with the results from the Monte Carlo simulation.

Through-the-Wall Sensing of Personnel Using Passive Bistatic WiFi Radar at Standoff Distances

In this paper, we investigate the feasibility of uncooperatively and covertly detecting people moving behind walls using passive bistatic WiFi radar at standoff distances. A series of experiments was conducted which involved personnel targets moving inside a building within the coverage area of a WiFi access point. These targets were monitored from outside the building using a 2.4-GHz passive multistatic receiver, and the data were processed offline to yield range and Doppler information. The results presented show the first through-the-wall (TTW) detections of moving personnel using passive WiFi radar. The measured Doppler shifts agree with those predicted by bistatic theory. Further analysis of the data revealed that the system is limited by the signal-to-interference ratio (SIR), and not the signal-to-noise ratio. We have also shown that a new interference suppression technique based on the CLEAN algorithm can improve the SIR by approximately 19 dB. These encouraging initial findings demonstrate the potential for using passive WiFi radar as a low-cost TTW detection sensor with widespread applicability.

Meteor Orbit Determinations with Multistatic Receivers Using the MU Radar

The MU radar of RISH (Research Institute for Sustainable Humanosphere, Kyoto University), which is a MST radar (46.5 MHz, 1 MW peak power), has been successfully applied to meteor studies by using its very high versatility. The system has recently renewed with 25 channel digital receivers which significantly improved the sensitivity and precision of interferometer used in meteor observation. The transmission is now synchronized to GPS signals, and two external receiving sites with a ranging capability has additionally been operated in order to determine the trajectories and speeds of meteoroids.

Fine Scale 3D Wind Field Observation With a Multistatic Equatorial Atmosphere Radar

Radar observation is widely recognized as an essential technique to study the three-dimensional dynamics of the atmosphere with a high temporal resolution. Conventional monostatic radar with a single aperture or array, however, has rather limited spatial resolution. This is because this radar can only obtain the radial component of the wind velocity, and thus it must observe at least three spatially separate target volumes to estimate the three components of the wind vector. In this paper, a multistatic radar observation technique, which uses two receiver arrays together with a high-gain rapid scanning mesosphere-stratosphere-troposphere (MST) radar, is presented. Multistatic receiver arrays obtain non-radial components of the wind velocity; hence, the technique enables us to determine 3D wind velocity at each minimum resolution volume. Consequently, it eliminates estimation error caused by horizontal inhomogeneity of the wind field and improves spatial resolution. Applying this technique, we made a series of tropospheric observations in September 2004, utilizing a newly developed digital receiver system at the Equatorial Atmosphere Radar, West Sumatra, Indonesia. Each receiver antenna is equipped with this digital receiver and recording system, which is constructed with a cost-effective ready-made digital receiver PCI board and a PC. This structure enables us to swing the receiving beam after an observation using digital beamforming techniques. First, the importance and the effectiveness of ground clutter rejection using an adaptive spatial filter, which is another advantage of digital receiver systems, is demonstrated. Then for the first time an example profile of a 3D wind velocity field with 1-km horizontal resolution at 3.8 km altitude is presented. Considering the accuracy of the multistatic radar system, the resulting wind field shows the existence of significant perturbation that previously would have been averaged in conventional monostatic radar observations.

Multistatic lidar profiling of urban atmospheric aerosols

It has become increasingly important to obtain information on the vertical distribution, i.e., profile, of aerosols in the open atmosphere. To complement data obtained from a monostatic Raman lidar, a multistatic receiver configuration was designed to take measurements of the parallel and perpendicular polarization scattered components for altitudes from 10 m to 1000 m above the ground. The measurements, taken at night, were used to form a polarization ratio that was subsequently fitted using Mie theory and a trimodal lognormal aerosol distribution. Experimental results revealed the presence of strong variations in the aerosol distribution within the nighttime planetary boundary layer with some time sequences revealing rapid temporal and spatial changes. Subsequent modeling of the aerosol profile suggested that the observed aerosol variations may depend on a combination of factors, including altitude, composition, and number density. However, in instances when the atmosphere was found to be uniformly mixed, retrieval of aerosol parameters (number density, median radius, and geometric standard deviation) was obtained.