US 7,539,613 B2
Device for recovering missing frequency components
Masashi Takada, Kanagawa (Japan)
Assigned to Oki Electric Industry Co., Ltd., Tokyo (Japan)
Appl. No. 10/545,435
PCT Filed Feb. 10, 2004, PCT No. PCT/JP2004/001427
§ 371(c)(1), (2), (4) Date Aug. 12, 2005,
PCT Pub. No. WO2004/072958, PCT Pub. Date Aug. 26, 2004.
Claims priority of application No. 2003-036607 (JP), filed on Feb. 14, 2003.
Prior Publication US 2007/0168185 A1, Jul. 19, 2007
Int. Cl. G10L 19/00 (2006.01); G10L 21/00 (2006.01); H03G 3/00 (2006.01)
U.S. Cl. 704—205  [704/225; 330/278; 455/118] 8 Claims
OG exemplary drawing
 
1. A band recovering device for recovering frequency components lying in a frequency band lost due to band-limitation of a sound signal, comprising:
a peak-limiting amplifier configured to amplify an input narrow-band voice signal while preventing a resulting amplified voice signal from exceeding a predetermined maximum amplitude;
a peak-limitation detector configured to detect whether or not a level of the amplified voice signal output from said peak-limiting amplifier is substantially coincident with the maximum amplitude;
an amplification controller configured to increase at least either one of an amplification factor and an amount of amplification of said peak-limiting amplifier until the level of the amplified voice signal output from said peak-limitation detector is substantially coincident with the maximum amplitude; and
a band recovering circuit configured to use a voice signal component of the amplified voice signal output from said peak-limiting amplifier and the input narrow-band voice signal to produce a band-recovered voice signal including the frequency components lying in the frequency band lost, the voice signal component being in frequency higher than the input narrow-band voice signal.