Digital Image Processing For Instantaneous Frequency Mapping

Seggie, D.A.; Doherty, Mark F.; Leeman, S.; Deighton, H. V.

doi:10.1117/12.966494

Cited by 2 publications

(1 citation statement)

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“…A number of stratagems have been devised to handle this difficulty: for example, adding in a low-frequency sinusoid (Ferrari et al, 1984;Mayo et al, 1985;Ranalli, 1985), or even a dc offset , to the rf A-line prior to FM demodulation. These ad hoc techniques may be viewed as forms of zero manipulation, albeit less powerful than the real zero conversion method ( Seggie et al, 1986). The above discussion suggests also how such approaches may inject apparent envelope information into FM images.…”

Section: •R • 1 F••••+' (Tn+ 1 --Tn) --(Tn+ 1 --T•) •(T)dtmentioning

confidence: 98%

Pulse–echo imaging via zero manipulation

Seggie

Doherty

Leeman

1987

The Journal of the Acoustical Society of America

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The use of frequency demodulation in ultrasound pulse-echo imaging is assessed. It is shown that the straightforward display of instantaneous frequency information results in an image that appears to bear little relationship to object structure. However, a modified frequency demodulation technique which overcomes this difficulty, and also offers a degree of on-line image processing power, is proposed. The method allows both the envelope and phase of the signal to be accessed by frequency demodulation processing, and is applicable to a wider class of data, such as seismic and speech signals.

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Section: •R • 1 F••••+' (Tn+ 1 --Tn) --(Tn+ 1 --T•) •(T)dtmentioning

confidence: 98%

Pulse–echo imaging via zero manipulation

Seggie

Doherty

Leeman

1987

The Journal of the Acoustical Society of America

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The Instantaneous Frequency of a Sinewave Squelched Bandlimited Signal

et al. 1986

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We study the instantaneous frequency of a signal which is formed by the summation of a sinewave and a bandlimited signal. We refer to the composite signal as a sinewave squelched or simply a squelched signal. We study the behavior of the squelched signal at its real zeros and extrema. In particular when the sinewave frequency is equal to the largest frequency in the signal's spectrum and its amplitude is greater than the signal's maximum amplitude, the analytic signal corresponding to this resultant signal (hereafter abbreviated as RZ signal) has only real zeros which contain all of the bandlimited signal's information. FM systems often use zero crossing techniques in the demodulation process. For a process with a normal amplitude distribution, we derive a relationship between the zero crossing density of an RZ converted signal and that of the original signal. One application of these analyses is in ultrasonic FM imaging. We give an explanation for the behavior of the FM imaging system as a function of amplitude and frequency of the added cosine.

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Digital Image Processing For Instantaneous Frequency Mapping

Cited by 2 publications

References 1 publication

Pulse–echo imaging via zero manipulation

Pulse–echo imaging via zero manipulation

The Instantaneous Frequency of a Sinewave Squelched Bandlimited Signal

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