## Filter Results

Displaying Results 1 - 6 of 6
• ### Nonlinear frequency modulation chirps for active sonar

Publication Year: 1999, Page(s):312 - 316
Cited by:  Papers (22)  |  Patents (2)
| | PDF (432 KB)

Range sidelobe suppression in pulse-compression radars and sonars is conventionally performed using amplitude windowing in either the time or frequency domains. Using peak power limited transmitters, this inevitably causes a degradation in the signal-to-noise ratio available at the receiver output owing to shading or mismatch losses. Nonlinear frequency modulation (NLFM) chirps have been suggested... View full abstract»

• ### Ship target detection for HF groundwave shipborne OTH radar

Publication Year: 1999, Page(s):305 - 311
Cited by:  Papers (9)
| | PDF (580 KB)

The spreading of the first order Bragg lines that result from movement of the radar platform will obscure targets with Doppler frequencies within the range of this spreading. This is the main difficulty for HF groundwave OTH radar in detecting ship targets in a shipboard environment. In the paper, the properties of the spread spectrum are analysed with the aid of synthetic aperture theory, the pos... View full abstract»

• ### Cell-averaging CFAR detection in compound clutter with spatially correlated texture and speckle

Publication Year: 1999, Page(s):279 - 284
Cited by:  Papers (8)
| | PDF (428 KB)

The authors study the problem of a CA-CFAR, cell-averaging constant false alarm rate, detection of a Swerling II target model embedded in spatially correlated K-distributed clutter. The clutter model consists of the product of two components called texture' and speckle'. Two cases are analysed; in the first case, the speckle samples are correlated and the texture samples are independent while in... View full abstract»

• ### Application of chaos theory to ray tracing in ducts

Publication Year: 1999, Page(s):298 - 304
Cited by:  Papers (7)
| | PDF (604 KB)

To predict the radar cross section of large ducts and cavities it is common to employ ray tracing methods of one kind or another. Electromagnetic engineers traditionally employ a first-order ray theory based on the Deschamps (1972) formulation. This is not the only formulation and it is shown that the semi-classical tangent-plane methods employed in quantum physics offer some advantages. The speci... View full abstract»

• ### Application of momentary Fourier transform to SAR processing

Publication Year: 1999, Page(s):285 - 297
Cited by:  Papers (2)
| | PDF (1020 KB)

A common technique in signal and image processing is to extract a portion of the signal by windowing, and then perform the DFT on the window contents. The momentary Fourier transform (MFT) applies to the particular case where the window is moved one data sample along the signal between successive transforms. An alternative derivation of the recursive form of the MFT using general matrix transforms... View full abstract»

• ### Duration of radar false alarms in band-limited Gaussian noise

Publication Year: 1999, Page(s):273 - 278
Cited by:  Papers (2)
| | PDF (408 KB)

The duration of threshold crossings is investigated for the envelope of band-limited Gaussian noise. The results are applied to the estimation of false alarm times for radar detection and it is shown that the average duration of threshold crossings may be much less than the reciprocal of the noise bandwidth. The average shape of large excursions of the envelope of noise is given by the autocorrela... View full abstract»