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    Item type:Publication, Access status: without files ,
    Proceedings / International Radar Symposium (IRS), 2011 : 7 - 9 Sept. 2011, Leipzig, Germany
    (IEEE, 2011)
    Publicationtype: Conference Proceedings
      13
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    Ordered statistic CFAR technique : an overview
    (IEEE, 2011)
    Rohling, Hermann
    Adaptive radar target detection in a noise or clutter environment is a very important device in each radar receiver. In almost all detection procedures the received echo signal amplitude is simply compared with a certain threshold. The main objective in target detection is to maximize the target detection probability under the constraints of very low and Constant False Alarm Rate (CFAR). The noise and clutter background will be described by a statistical model with e.g. independent and identically Rayleigh or exponentially distributed random variables of known average noise power. But in practical applications this average noise or clutter power is absolutely unknown and can additionally vary over range, time and azimuth angle. Therefore this paper describes some of the so-called range CFAR techniques for several different background signal situations in which the average noise power and some other additional statistical parameter are assumed to be unknown. All range CFAR techniques combine therefore an estimation procedure (to get precise or estimated knowledge about the noise power) and a decision step by applying an amplitude threshold to the echo signal amplitude inside the test cell. This general detection scheme has been analysed in many research activities and a large effort has been spent on this topic. The objective of this paper is to give a short characterisation and technical comparison of some of these important range CFAR detection schemes. © 2011 DGON.
    Publicationtype: Conference Paper
      212
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    Item type:Publication, Access status: without files ,
    Bistatic generalized ISAR concept with GPS waveform
    (Deutsche Gesellschaft für Ortung und Navigation (DGON), 2011)
    Lazarov, Andon Dimitrov
    ;
    Kabakchiev, Hristo
    ;
    Rohling, Hermann
    ;
    Kostadinov, Todor Pavlov
    Publicationtype: Conference Paper
      28
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    Mismatched filter applied to complementary code design
    (IEEE, 2011)
    Bi, Jingying
    ;
    Rohling, Hermann
    Complementary code pairs have zero range sidelobe property, which is useful in radar applications to avoid stationary range sidelobe interferences. However, complementary code pairs exist only for limited codeword lengths. The general idea of complementary code design is extended in this paper by applying a mismatched filter procedure to the binary phase codeword pairs. Binary phase codeword pairs and the related mismatched filter impulse response coefficients are designed to fulfill the zero sidelobe property. © 2011 DGON.
    Publicationtype: Conference Paper
      13
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    Two-stage pedestrian classification in automotive radar systems
    (IEEE, 2011)
    Heuel, Steffen
    ;
    Rohling, Hermann
    Road and city traffic is dangerous for all car drivers and especially for pedestrians. Latest accident statistics [1] show that in 25% of all accidents pedestrians are involved. It is therefore important to protect especially those vulnerable traffic participants, e.g. by acoustic alarm signals or outside airbags, in case of an unavoidable accident. 24 GHz radar sensors with their all-weather capability are already in use in vehicles, and have great advantages compared with other automotive sensor systems. It has been described in [2], how the Doppler spectrum and the range profile are analyzed in a target recognition system for pedestrian detection. To increase the probability of correct classification, additional signal features have to be used. Also, a very fast target recognition system is required to respond and react quickly in dangerous situations. This paper is focused on a two-stage target classification system. Initially, the Doppler spectrum and range profile are extracted from the radar echo signal and applied in the recognition system. In a second step, additional features are calculated from the tracker which are fed back to the target recognition system to improve the system performance and to increase the probability of correct classification. © 2011 DGON.
    Publicationtype: Conference Paper
      21
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    Self-organized antenna array calibration
    (IEEE, 2011)
    Schröder, Christoph
    ;
    Rohling, Hermann
    The performance of direction finding algorithms is severely degraded by any phase and amplitude error between the adjacent elements of an array antenna. Due to analog hardware behavior these errors are time-varying and depend on temperature, component aging and other component specific characteristics. Therefore, the calibration coefficients have to be updated periodically and adaptively during radar system operation. © 2011 DGON.
    Publicationtype: Conference Paper
      23
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    HF radar observation of a tsunami near Chile after the recent great earthquake in Japan
    (IEEE, 2011)
    Dzvonkovskaya, Anna L.
    ;
    Figueroa, Dante
    ;
    Gurgel, Klaus-Werner
    ;
    Rohling, Hermann
    ;
    Schlick, Thomas
    A 9.0-magnitude undersea earthquake occurred near the coast of Japan on March 11, 2011, and generated a powerful tsunami, which propagated across the Pacific Ocean. The high-frequency (HF) surface wave radar is an operational tool for coastal monitoring worldwide. The oceanographic WERA HF radar located in Chile was in operation and provided measurements in real-time when the tsunami waves reached this region. For the first time impressive tsunami signatures of changing sea surface current velocities were observed by the HF radar system. The tsunami wave train can be clearly seen in the radar measurements. It was found to be significantly correlated with the water level measurements by tide gauges. © 2011 DGON.
    Publicationtype: Conference Paper
      23
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    Periodic code sets with ideal correlation properties
    (IEEE, 2011)
    Bi, Jingying
    ;
    Rohling, Hermann
    In this paper, code sets and the related mismatched filters are designed which have ideal correlation properties. It means that each code in the code set has not only a Dirac-like crosscorrelation function with its own mismatched filter, but also a zero crosscorrelation function when correlated with any mismatched filter for other codes. The design procedure is based on product theorem. One advantage of this procedure is the high flexibility of the code design. It is shown that a lot of code sets can be constructed. © 2011 DGON.
    Publicationtype: Conference Paper
      10