Álvaro Blanco-del-Campo

Statistical Analysis of a High-Resolution Sea-Clutter Database

This paper presents the statistical analysis of an experimental high-resolution sea-clutter database, collected with a high-resolution Ka-band radar at the south coast of Spain. The main motivation of this paper has been to check the validity of the available theoretical models for high-resolution sea-clutter against data corresponding to a range resolution of centimeters. The overall amplitude probability density function (pdf), the compatibility with a compound representation, and the average spectral behavior of the data are analyzed in detail. Results clearly show the suitability of the compound Gaussian model and, more precisely, that the empirical pdf is well modeled by the generalized K distribution with log-normal texture. A close agreement has also been found between the estimated clutter spectral density and a power-law model.

Traffic Surveillance System Based on a High-Resolution Radar

Traffic surveillance is an important civilian application of radars. The current high-resolution radars give new opportunities so that the traffic application may be redefined. In this paper, a traffic scenario with a high-resolution radar is presented. A range-bin alignment method, the Global Range Alignment, which comes from the focusing techniques in inverse synthetic aperture radar, is applied to obtain further capabilities than the usual velocity measurement: distinction between vehicle types via length estimation and adequate management in situations with simultaneous targets. Preliminary results from a real scenario using a high-resolution linear frequency-modulated continuous-wave millimeter-wave radar are shown.

Motion compensation for ISAR based on the shift-and-convolution algorithm

ISAR (inverse synthetic aperture radar) is a coherent technique that obtains images of targets by processing the echoes returned during the dwell time. A higher angular resolution than the antenna beamwidth may be obtained. In this paper we report high resolution ISAR images, which have been obtained from data captured by a millimeter-wave LFMCW (linear frequency modulated continuous wave) radar. The target translational motion compensation is achieved by means of a new parametric algorithm, which makes use of the shift-and-convolution technique. This image autofocusing algorithm is compared with prominent point processing (PPP) and phase gradient autofocus (PGA). Simulated and real data from the millimeter-wave LFMCW radar are used to verify the proposed technique, although the method is also applicable to any kind of coherent radar.

Transpose Return Relation Method for Designing Low Noise Oscillators

In this paper, a new linear method for optimizing compact low noise oscillators for RF/MW applications will be presented. The flrst part of this paper makes an overview of Leesons model. It is pointed out, and it is demonstrates that the phase noise is always the same inside the oscillator loop. It is presented a general phase noise optimization method for reference plane oscillators. The new method uses Transpose Return Relations (RRT) as true loop gain functions for obtaining the optimum values of the elements of the oscillator, whatever scheme it has. With this method, oscillator topologies that have been designed and optimized using negative resistance, negative conductance or re∞ection coe-cient methods, until now, can be studied like a loop gain method. Subsequently, the main disadvantage of Leesons model is overcome, and now it is not only valid for loop gain methods, but it is valid for any oscillator topology. The last section of this paper lists the steps to be performed to use this method for proper noise optimization during the linear design process and before the flnal non-linear optimization. The power of the proposed RRT method is shown with its use for optimizing a common oscillator, which is later simulated using Harmonic Balance (HB) and manufactured. Then, the comparison of the linear, HB and measurements of the phase noise are compared.

Instrumental CWLFM High-Range Resolution Radar in Millimeter Waveband for ISAR Imaging

This paper shows a High-Range Resolution (HRR) Radar prototype development, transmitting in millimeter-wave band. The waveform selected to be used is the continuous-wave linear frequency modulation (CWLFM), which allows, at the same time, good range resolution, moderate unambiguous doppler range and reasonable operational range taking into account that high-frequency band is used. The radar prototype looks for High-Range Resolution (HRR) characteristics as well as flexibility, in order to obtain the best Inverse Synthetic Aperture Radar (ISAR) images possible depending on the applications and targets involved. That is, depending on the speed and targets trajectories, some radar features, such as transmitted bandwidth, modulator frequency or sampling frequency, play a key role in obtaining the best possible results while using lowest electrical requirements.

A coherent Radon transform for small target detection

The Radon transform can be used to implement grid based “track-before-detect” processors. The approach can be described as a range alignment step followed by non-coherent integration. In this paper, a modification of the conventional direct Radon transform is proposed to coherently integrate the energy of the target. In this way, the noise and clutter contributions to each projection angle can be minimized and the overall performance of the system will improve.

Scan rate selection for coherent high-resolution maritime surveillance radar: An experimental study

Scan rate selection has a crucial impact on the performance of maritime surveillance systems. In this work, a sea clutter database has been used to obtain experimental insight on the trade-off between within-scan and scan-to-scan integration. This paper extends the previous empirical studies to the case of sub-meter range resolution Ka-band coherent sea-clutter data. Results show a clear performance improvement for faster scan rates provided that the number of coherently integrated samples is high enough.

Small-target detection in sea clutter based on the Radon Transform

Small target detection in sea clutter is a challenging problem. This paper presents a novel and heuristic approach based on the application of the Radon Transform to a set of consecutive range profiles. The performance of the detection technique has been tested with real sea clutter data, acquired with a high resolution CWLFM (continuous wave linear frequency modulated) millimetre-wave radar demonstrator. Results show that performing the detection on the Radon domain makes the detection of very small targets possible while keeping the false alarm rate controlled.

Microwave Power FET DC Model Extraction through Isothermal Non-Pulsed Measurements

In this work a new approach to extract the experimental fitting parameters of a microwave power FET temperature dependent DC-model is presented. The suggested procedure avoids the possibility of multiple model solutions by eliminating the measurements temperature dependence. This is accomplished by making use of isothermal measurements which in turn are obtained following a simple non-pulsed approach. The proposed technique was applied to a commercial X band MMIC FET power amplifier