A Quantitative Analysis of Sea Clutter Decorrelation with Frequency Agility

Beasley, Eric W.; Ward, H.R.

doi:10.1109/taes.1968.5409001

Cited by 26 publications

(8 citation statements)

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“…Therefore to further suppress the Doppler artefacts on a single acquired frame, we propose a signal processing technique known as split spectrum processing (SSP). SSP was first introduced in radar to resolve concealed targets in randomly distributed reflection, known as clutter [22]. Subsequent application of this method was applied to ultrasound as a frequency agility technique for flaw detection in materials without the typical loss of spatial resolution associated with axial averaging.…”

Section: Introductionmentioning

confidence: 99%

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part IV): split spectrum processing in rotary catheter probes

Vuong¹,

Lee²,

Luk³

et al. 2014

Opt. Express

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We report a technique for blood flow detection using split spectrum Doppler optical coherence tomography (ssDOCT) that shows improved sensitivity over existing Doppler OCT methods. In ssDOCT, the Doppler signal is averaged over multiple sub-bands of the interferogram, increasing the SNR of the Doppler signal. We explore the parameterization of this technique in terms of number of sub-band windows, width and overlap of the windows, and their effect on the Doppler signal to noise in a flow phantom. Compared to conventional DOCT, ssDOCT processing has increased flow sensitivity. We demonstrate the effectiveness of ssDOCT in-vivo for intravascular flow detection within a porcine carotid artery and for microvascular vessel detection in human pulmonary imaging, using rotary catheter probes. To our knowledge, this is the first report of visualizing in-vivo Doppler flow patterns adjacent to stent struts in the carotid artery.

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Section: Introductionmentioning

confidence: 99%

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part IV): split spectrum processing in rotary catheter probes

Vuong¹,

Lee²,

Luk³

et al. 2014

Opt. Express

View full text Add to dashboard Cite

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“…The results are shown in Figs. [13][14][15]. They are based on the characteristics of a missile carrying an active radar seeker which acquires the target at a range of 10,000 ft.…”

Section: Discussionmentioning

confidence: 99%

“…The variance of angular error caused by clutter is related to signal-to-clutter power ratio at the output of the integrator by 3 = D.25/3VOS/<7)o (13) The signal-to-clutter ratio out of the integrator is related to that at the input by 1Mi OS/C% = N.(S/C)t (14) Here, N e is the effective number of independent clutter samples contained in the N pulses that are integrated. This value is generally different from the value applicable to the glint.…”

Section: + 2 Y* ^-* Rmentioning

confidence: 99%

Homing Radar Tracking Accuracy Improvement with Frequency Diversity

Jones

Mickle

Swetnam

1971

Journal of Spacecraft and Rockets

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Available theory concerning glint reduction by usage of frequency diversity in a radar tracker is reviewed and unified. The theory was verified experimentally using 1) a target consisting of two corner reflectors (which could be representative of a low-flying aircraft and its sea image), 2) an isolated aircraft in level flight, and 3) a boat in a sea-clutter background. A simulation was used to reflect this glint reduction into a reduction of miss distance. The rms miss is reduced by as much as a factor of three corresponding to usage of nine carrier frequencies.

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“…With finite observations, 71, the estimate will have some dispersion about the quantile value. U,, that allows the values of neighboring quantiles to influence the output [14]. It should be noted that the performance of the OS filter will generally improve with increasing observations 71 since the variance will decrease (i.e., the random nature of the grains echoes will be reduced).…”

Section: ) Is a Fixed Constant And E[x()]mentioning

confidence: 99%

Analysis of order-statistic CFAR threshold estimators for improved ultrasonic flaw detection

Saniie

Nagle

1992

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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In the pulse-echo method using broadband transducers, flaw detection can be improved by using optimal bandpass filtering to resolve flaw echoes surrounded by grain scatterers. Optimal bandpass filtering is achieved by examining spectral information of the flaw and grain echoes where frequency differences have been experimentally shown to be predictable in the Rayleigh scattering region. Using optimal frequency band information, flaw echoes can then be discriminated by applying adaptive thresholding techniques based on surrounding range cells. The authors present order-statistic (OS) processors, ranked and trimmed mean (TM), to robustly estimate the threshold while censoring outliers. The design of these OS processors is accomplished analytically based on constant false-alarm rate (CFAR) detection. It is shown that OS-CFAR and TM-CFAR processors can detect flaw echoes robustly with the CFAR of 10 (-4) where the range cell used for the threshold estimate contains outliers.

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A Quantitative Analysis of Sea Clutter Decorrelation with Frequency Agility

Cited by 26 publications

References 0 publications

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part IV): split spectrum processing in rotary catheter probes

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part IV): split spectrum processing in rotary catheter probes

Homing Radar Tracking Accuracy Improvement with Frequency Diversity

Analysis of order-statistic CFAR threshold estimators for improved ultrasonic flaw detection

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