Boots – shoes – and leggings
Patent
1993-02-04
1994-08-09
Black, Thomas G.
Boots, shoes, and leggings
381 46, 381 47, 381 94, G10L 300
Patent
active
053372514
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of detecting a useful signal affected by noise.
2. Discussion of the Background
One of the great problems in signal processing, simple to enunciate but very complex to resolve, consists in determining the presence or the absence of a useful signal buried in additive noise.
Various solutions can be envisaged. It is possible to use, as a variable, the instantaneous amplitude of the received or processed signal by reference to an experimentally-determined threshold.
It is also possible to use, as a variable, the energy of the total signal over a time slice of duration T, by thresholding this energy, still experimentally.
These thresholdings allow a first assumption on the presence or the absence of the signal. They are, moreover, applicable to any signal. Hence, they are complemented by "confirmation" systems, defining "near-certain" criteria, specific to the type of useful signal, when the nature of the latter is known in advance.
Such a complementary system is widely used in speech processing and may consist, for example, in extraction of "pitch" or in evaluation of the minimum energy of a vowel.
SUMMARY OF THE INVENTION
The subject of the present invention is a method of detecting a useful signal affected by noise, determining the detection threshold as rigourousiy as possible, and able to operate self-adaptively.
According to the invention, the expected signal
oise ratio of the signal to be processed is available, and a measurement of the estimated noise alone is available, a measurement enumerated over M points, this noise being white or made to be white, the mean energy of the noise over these M points is calculated, a slice of N points of noise-affected signal is taken, the mean energy of these N points is calculated, the theoretical detection threshold is calculated, the ratio between the two said mean energies is calculated, and this ratio is compared with the said threshold .
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 illustrates an exemplary embodiment of the invention; and
FIG. 2 illustrates a process used by the present invention; and
FIG. 3 illustrates a second embodiment of the present invention.
THE DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several view, and more particularly to FIG. 1 thereof, there is illustrated an exemplary hardware embodiment of the present invention. Reference No. 6 designates a speech detector which detects if speech is contained in an input audio sample. The algorithm used by the speech detector 6 requires a measurement of noise alone 2 and a signal which may or may not contain speech. Speech files 4 contain the audio samples/signals which may or may not contain speech. The audio samples can be mixed with noise. The speech detector 6 contains a segmentation coarseness changeover switch 8 which determines if diction of the speech files is to be segmented in a coarse manner.
FIG. 2 illustrates a process which is performed by the present invention. First, in step 10, a signal which is noise alone is measured. In step 12, a combined speech and noise signal is measured. Step 14 then calculates a ratio of the energy of the combined speech and noise signal to the energy of the measured noise signal. Step 16 then calculates a detection threshold which is described in detail below, and step 18 compares the ratio calculated in step 14 with the detection threshold calculated in step 16.
Step 20 then determines if speech is present using the comparison result of step 18. If there is no speech present, the process ends. If step 20 indicates speech is present, flow proceeds to step 22 which
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Black Thomas G.
Nguyen Tan Q.
Sextant Avionique
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