Archives

Volume 2 Number 3 March 2016

Heterogeneous Performance Evaluation of Sophisticated Versions of CFAR Detection Schemes


Authors: Mohamed B. El Mashade
Pages: 35-52
Abstract
The detection of radar targets in a background, the statistical parameters of which are unknown and may not be stationary, can be effectively achieved through CFAR processors. The CA-CFAR scheme performs optimally for homogeneous and exponentially distributed clutter observations. However, it exhibits severe performance degradation in the presence of outlying target returns in the reference set or in regions of abrupt change in the background clutter power. The OS-CFAR processor has been proposed to alleviate both of these problems. Although this processor may treat target multiplicity quite well, it lacks effectiveness in preventing excessive false alarms during clutter power transitions. The TM-CFAR algorithm, which implements trimmed averaging after ordering, can be considered as a modified version of OS technique. By knowingly excising the ordered samples, the TM detector may actually perform somewhat better than the OS processor. To simultaneously exploit the merits of CA, OS, and TM schemes, two combinations namely CA_OS and CA_TM have been recently suggested. Each one of these versions optimizes good features of two CFAR detectors depending on the characteristics of clutter and searched targets with the goal of enhancing the detection performance under constant level of false alarm. It is realized by parallel operation of two standard types of CFAR schemes. Our goal in this paper is to analyze these two developed versions, in heterogeneous situations, to show to what extent they can improve the behavior of the conventional CFAR processors.

Seasonal Incidence of Campoletis chloridae Uchida?A Larval Parasitoid of Helicoverpa armigera Hubner on Chickpea in Central (U.P.)


Authors: Y. P. Malik ; Rishi Pal
Pages: 31-34
Abstract
Study on seasonal incidence of Campoletis chloridae Uchida, a larval parasitoid of Helicoverpa armigera (Hubner), in chickpea crop was conducted at Kanpur during rabi 2007-08. The parasitoid made its first appearing during 3rd standard meteorological week of the year in different date of sowing and verities varied between 4.4 to 93.3 %. The verity Udai sown at November 11-2007 D1 and D2 November 28 was Mean ± SD 44.75 ± 31.93 and 42.61 ± 27.65, verity Avarodhi date of sown of October 21 2007 D1 and November 17 2007 D2 was Mean ± SD 32.43 ±29.22 and 36.36 ± 29.22 and verity Pragati date of sowing November 17 2007 D1 was Mean ± SD 31.47 ± 31.47 ± 26.79 during December, January, February and March respectively. The per cent parasitization of C. chloridae showed a negative correlation with means temperature, sunshine hours and relative humidity. Where a significant positive correlation was found between per cent parasitization rainfall and wind velocity.