Frequency thinning device and method for compressing information by thinning out frequency components of signal
View Patent ↗A device and a method for compressing signal information by removing (thinning out) the signal component of a signal in a specific frequency band. Firstly, an input time-series signal (e.g., a PCM signal) is converted by an analyzer ( 11 ) into a spectrum signal. Next, of the bands obtained by dividing the spectrum equally into bands, the band having a predetermined or higher correlation in the spectrum distribution with the lower frequency band is specified as a harmonic band by a frequency band masking unit ( 12 ). Then, a removal band from which the spectrum is to be removed is determined from the harmonic band, and the spectrum signal of this removal band, from which the spectrum component has been removed (namely the frequency component has been thinned out), is fed to a synthesizer ( 13 ).
1. A frequency thinning device for compressing a given signal by removing signal components in a specific frequency band, comprising:
an analyzer for generating frequency spectrum signals in a plurality of frequency bands, and
a frequency band masking unit for determining correlation coefficients for all the possible combinations of selected two bands, determining as a fundamental frequency band the band which has correlation coefficients equal to or less than a predetermined value for all the possible combinations of bands having the lowest frequency lower than that of the band among all the bands received from the means for generating, determining the bands other than the fundamental frequency band as higher harmonic bands, and determining, among the higher harmonic bands, bands of which the spectra are to be removed, as removal bands.
2. The frequency thinning device according to claim 1 , wherein the frequency spectrum signal to be generated is a short time spectrum signal.
3. The frequency thinning device according to claim 1 , wherein signal components in a frequency band on a lower frequency side are removed, among frequency bands having a correlation not smaller than the predetermined value.
4. A frequency thinning device comprising:
an analyzer for generating a spectrum signal representative of a spectrum of a signal to be thinned;
a frequency band masking unit for determining correlation coefficients for all the possible combinations of selected two bands, determining as a fundamental frequency band the band which has correlation coefficients equal to or less than a predetermined value for all the possible combinations of bands having the lowest frequency lower than that of the band among all the bands received from the spectrum generating means, determining the bands other than the fundamental frequency band as higher harmonic bands; and
wherein the frequency band masking unit partially removes spectrum components contained in the higher harmonic bands.
5. The frequency thinning device according to claim 4 , wherein said frequency band masking unit removes spectrum components contained in a specific removal band among the spectrum components contained in the higher harmonic band, and spectrum components contained in a band neighboring the removal band on the lower frequency side having substantially a same band width as a band width of the removal band are excluded for removal.
6. The frequency thinning device according to claim 5 , wherein the signal to be thinned is a PCM (Pulse Code Modulation) signal obtained by sampling and quantizing an analog audio signal.
7. The frequency thinning device according to claim 4 , wherein the signal to be thinned is a PCM (Pulse Code Modulation) signal obtained by sampling and quantizing an analog audio signal.
8. A frequency thinning method for compressing a given signal by removing signal components in a specific frequency band, comprising the steps of:
generating frequency spectrum signals in a plurality of frequency bands;
determining correlation coefficients for all the possible combinations of selected two bands;
determining as a fundamental frequency band the band which has correlation coefficients equal to or less than a predetermined value for all the possible combinations of bands having the lowest frequency lower than that of the band among all the bands;
determining the bands other than the fundamental frequency band as higher harmonic bands; and
determining, among the higher harmonic bands, bands of which the spectra are to be removed, as removal bands.
9. A computer readable storage medium storing a program comprising:
an analyzer for generating a spectrum signal representative of a spectrum of a signal to be thinned;
a frequency band masking unit for determining correlation coefficients for all the possible combinations of selected two bands, determining as a fundamental frequency band the band which has correlation coefficients equal to or less than a predetermined value for all the possible combinations of bands having the lowest frequency lower than that of the band among all the bands received from the spectrum generating means, and determining the bands other than the fundamental frequency band as higher harmonic bands; and
wherein the frequency band masking unit partially removes spectrum components contained in the higher harmonic bands.