Telecommunications – Receiver or analog modulated signal frequency converter – With particular receiver circuit
Reexamination Certificate
2003-08-21
2009-08-04
Le, Lana N (Department: 2614)
Telecommunications
Receiver or analog modulated signal frequency converter
With particular receiver circuit
C455S334000, C455S570000
Reexamination Certificate
active
07570937
ABSTRACT:
Comfort noise is derived from a white noise signal by filtering the white noise signal in a QMF bank to produce comfort noise signal that is selectively coupled to at least one channel in a telephone. Preferably, a plurality of QMF banks are used and the magnitude of the white noise into each filter is controlled in accordance with the magnitude of the signal in a corresponding analysis sub-band in a channel. In accordance with another aspect of the invention, the signals from higher frequency analysis sub-bands are combined and control a single input to a QMF bank, thereby increasing the low frequency resolution of the comfort noise. In accordance with another aspect of the invention, the QMF banks are cascaded upwardly (the output of one bank is coupled to the low pass input of the next bank), which also enhances the low frequency resolution of the comfort noise.
REFERENCES:
patent: 5630016 (1997-05-01), Swaminathan et al.
patent: 5960389 (1999-09-01), Jarvinen et al.
patent: 6625284 (2003-09-01), Ariyama
patent: 6708024 (2004-03-01), Yip
patent: 2003/0063662 (2003-04-01), Uchino et al.
patent: 2003/0123535 (2003-07-01), Nayak
Gandhi et al.,A New Approach to the Design of Two-Channel Perfect Reconstruction Filter Banks, 0-7803—5008-1/98; © 1998 IEEE, pp. 405-408.
Gandhi et al.,A Computationally Efficient Design of Two-Band QMF Banks Based on the Frequency Sampling Approach, 0-7803-4455-3/98, © 1998 IEEE, pp. V-421-424.
Gandhi et al.,Design of Two-Channel Low Delay Perfect Reconstruction Filter Banks, 0-7803-5148-7/98, © 1998 IEEE, pp. 1655-1659.
Digital Signal Processing, “Quadrature Mirror Filter”, EECE UBC, pp. 46-56.
Nowlin Robert Winston
Suppappola Seth
Acoustic Technologies Inc.
Le Lana N
Wille Paul F.
LandOfFree
Comfort noise generator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Comfort noise generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Comfort noise generator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-4086168