| Patent Number |
Title Of Patent |
Date Issued |
| 7570937 |
Comfort noise generator |
August 4, 2009 |
| 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 |
| 7555117 |
Path change detector for echo cancellation |
June 30, 2009 |
| A path change is detected by multiplying the energy of a signal on the output of a summation circuit in one channel of a telephone by a constant to produce a product. The product is compared with the energy of a signal on the input of the summation circuit. A path change is indicated whe |
| 7492889 |
Noise suppression based on bark band wiener filtering and modified doblinger noise estimate |
February 17, 2009 |
| In a noise suppresser, an input signal is converted to frequency domain by discrete Fourier analysis and divided into Bark bands. Noise is estimated for each band. The circuit for estimating noise includes a smoothing filter having a slower time constant for updating the noise estimate |
| 7454010 |
Noise reduction and comfort noise gain control using bark band weiner filter and linear attenuat |
November 18, 2008 |
| A combination of noise suppression using a Bark band modified Weiner filter and linear noise reduction improves elimination of noise in a telephone. A detector for detecting long, non-speech intervals is coupled to the output of the noise suppresser and controls selection of noise su |
| 7295976 |
Voice activity detector for telephone |
November 13, 2007 |
| Voice activity is detected by comparing a signal with two thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adj |
| 7046792 |
Transmit/receive arbitrator |
May 16, 2006 |
| The amplitudes of a signal on the microphone input of a telephone and a signal on the line input of the telephone are compared with each other and with two thresholds. The comparisons are sampled and the samples control an up-down counter. The count in the counter is compared with two |
| 7031461 |
Robust adaptive filter for echo cancellation |
April 18, 2006 |
| An adaptive filter is programmed with an algorithm based on a normalized Least Mean Squares (nLMS) algorithm that adapts each sample time. The algorithm is modified to be more efficient in a variety of DSPs by computing multiple errors, one per sample, before updating coefficients. T |
| 6891809 |
Background communication using shadow of audio signal |
May 10, 2005 |
| Data is transferred by delaying an audio signal less than fifty milliseconds to produce a shadow signal and combining the shadow signal with the audio signal. The shadow represents the data to be transferred A telephone constructed in accordance with the invention has at least two, s |
| 6847930 |
Analog voice activity detector for telephone |
January 25, 2005 |
| Voice activity is detected by comparing an analog signal with two voltage thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the th |
| 6798881 |
Noise reduction circuit for telephones |
September 28, 2004 |
| A system for processing audio signals in two channels, wherein each channel includes a plurality of band pass filters for dividing the signal in each channel into a plurality of bands and a plurality of variable gain amplifiers coupled one each to a band pass filter. Control logic couple |
| 6754337 |
Telephone having four VAD circuits |
June 22, 2004 |
| Voice activity is detected by comparing a signal with two thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adj |
| 6625286 |
Precise amplitude correction circuit |
September 23, 2003 |
| Amplitude is corrected by subtracting a component signal from a composite signal to produce a remainder signal, correlating the remainder signal with the component signal to produce a product signal, averaging the product signal, and adjusting the magnitude of the component signal in |
| 6608898 |
Band pass and notch filters for echo reduction with less phase distortion |
August 19, 2003 |
| A complementary comb filter includes a plurality of band pass filters and a plurality of notch filters, wherein the notch filters have the same center frequencies as the band pass filters or the same center frequencies as the dead bands defined by the band pass filters. Phase distortion |
| 6492865 |
Band pass filter from two filters |
December 10, 2002 |
| A band pass filter includes a pair of filters having different center frequencies and a difference amplifier coupled to the outputs of the filters. The filters preferably have response curves that intersect at -3 dB. The separation of the center frequencies determines, in part, the r |
| 6421443 |
Acoustic and electronic echo cancellation |
July 16, 2002 |
| A transmitted signal is coupled through a coarse delay and a fine delay to one input of a correlator. Another input of the correlator is coupled to a received signal. The delays are adjusted for maximum correlation and the output of the fine delay is subtracted from the received signal t |
| 6404279 |
Band pass filter with improved group delay |
June 11, 2002 |
| An electrical signal is applied to a band pass filter, a first notch filter, and a second notch filter in any order. The center frequencies of the notch filters straddle the pass band of the band pass filter. The notch filters improve group delay and steepen the skirts of the response |
| 6404278 |
Separation of plural band pass filters |
June 11, 2002 |
| The separation of a adjacent band pass filters is improved, without changing the filters, by inverting the output signals from alternate filters and not inverting the remaining output signals. All the output signals are then summed. The result is a deeper notch in the frequency respo |
| 6379323 |
Bio erodable myringotomy tube |
April 30, 2002 |
| A bio erodable myringotomy tube which is bio erodable and does not require removal. |
| 6301364 |
Tagging echoes with low frequency noise |
October 9, 2001 |
| A low pass limited, low frequency pseudo-random noise signal is added to the input signal for tagging the input signal in order to facilitate correlation with an echo. |
| 6278785 |
Echo cancelling process with improved phase control |
August 21, 2001 |
| An echo is cancelled from a composite signal by providing a coarse phase adjustment, a fine phase adjustment, an amplitude correction, and then subtracting the phase shifted signal from the composite signal. In the coarse adjustment, the phase is slightly under-corrected, thereby allowin |
| 6268766 |
Band pass filter from two notch filters |
July 31, 2001 |
| A band pass filter includes a pair of notch filters having different notch frequencies and a difference amplifier coupled to the outputs of the notch filters. The notch filters preferably have response curves that intersect at -3 dB. The separation of the notch frequencies determines, in |
| 6255877 |
Wide range, variable phase shift circuit |
July 3, 2001 |
| A filter includes an FET and a capacitor in a phase shift network wherein the FET operates as a variable resistor. An impedance multiplier is coupled to the FET for increasing the range of resistance of the FET. |
| 6252967 |
Reducing acoustic feedback with digital modulation |
June 26, 2001 |
| Sound is converted into an electrical signal by a microphone and is converted into an inaudible, digitally modulated signal that is combined with the electrical signal from the microphone, amplified, and converted into sound waves by a speaker. Any sound traveling from the speaker back |
| 6191334 |
Perforation repair device and method |
February 20, 2001 |
| A dissolvable repair device, and a method utilizing the same, that is intended to aid in the repair and healing of a perforation in body tissue, such as a nasal septum. The repair device is intended to be placed over the area of the perforation to act as a scaffolding for the regrowth of |
| 6186965 |
Dissolvable septal splint and method of using the same |
February 13, 2001 |
| A septal splint that does not require surgical removal after implantation. The septal splint is designed to be dissolvable over a period of time, thereby eliminating the need to surgically remove the splint. Preferably, the splint dissolves within four weeks after placement. The dissolva |
| 6166573 |
High resolution delay line |
December 26, 2000 |
| A high resolution delay line includes a coarse delay having a minimum period of delay and a fine delay having a total delay, wherein the total delay is equal to or greater than half the minimum period. Each delay can be implemented in analog or digital form and the delay line can be |
| 6111957 |
Apparatus and method for adjusting audio equipment in acoustic environments |
August 29, 2000 |
| The signal in each channel of a stereo is modulated at an inaudible frequency by a replica of the original signal. The modulated signal is broadcast into a room by a loudspeaker and is picked up by a microphone. The microphone is coupled to the stereo, which includes a demodulator for |
