Correcting Or Reducing Quantizing Errors Patents (Class 375/243)
  • Patent number: 6069914
    Abstract: A watermark is embedded into video/image/multimedia data using spread spectrum methodology. The watermark is extracted from watermarked data without the use of an original or unwatermarked version of the data by using MPEG/JPEG coefficients. The image to be watermarked is divided into subimages. Each subimage is embedded with a watermark. When extracting the watermark, the result from each subimage is combined to determine the originally embedded watermark.
    Type: Grant
    Filed: September 19, 1996
    Date of Patent: May 30, 2000
    Assignee: NEC Research Institute, Inc.
    Inventor: Ingemar J. Cox
  • Patent number: 6069921
    Abstract: A system and method for reducing quantizing noise is presented. In some Internet access and other dial-up services, modems or other sources connect into analog switching systems, and then are A/D-converted to reach remote switching offices. There, the digitized signal is converted back to analog, only to be re-digitized for T1 transmission. In the invention, the sample points used to re-digitize the signal are synchronized with those used to originally sample the signal, nearly eliminating second quantization noise.
    Type: Grant
    Filed: October 3, 1997
    Date of Patent: May 30, 2000
    Assignee: AT&T Corporation
    Inventor: Alan Edward Kaplan
  • Patent number: 6064698
    Abstract: A code string having a changed compression ratio is regenerated at a high speed. A quantizing accuracy and a normalizing coefficient to be changed are calculated by a quantizing-accuracy and normalizing-coefficient determining circuit without needing to dequantize the generated code. Then, the previously generated code is requantized by a quantized-spectrum calculating circuit in accordance with the calculated quantizing accuracy and the normalizing coefficient.
    Type: Grant
    Filed: November 18, 1997
    Date of Patent: May 16, 2000
    Assignee: Sony Corporation
    Inventor: Takashi Koike
  • Patent number: 6016327
    Abstract: An electronic memory system and method for use in a system for reducing quantizing noise is presented. In some Internet access and other dial-up services, modems or other sources connect into analog switching systems, and then are A/D-converted to reach remote switching offices. There, the digitized signal is converted back to analog, only to be re-digitized for T1 transmission. In the invention, the sample points used to re-digitize the signal are encoded using a dedicated electronic memory structure which permits efficient determination of valid data points.
    Type: Grant
    Filed: October 3, 1997
    Date of Patent: January 18, 2000
    Assignee: AT&T Corporation
    Inventor: Alan Edward Kaplan
  • Patent number: 6014175
    Abstract: For preparation of sampled values represented as two's complements, a two's complement clipping of the least significant bits(LSB) occurs. In place of the removed bits (LSB), the synchronization information (s(k)) is added with an average value depending on the quantization step. No dominant spectral lines for frequencies f greater than zero are permitted to occur in the useful spectrum for this synchronization information. Errors which are caused by removal of the least significant bits and by addition of the synchronization information are largely compensated by these features.
    Type: Grant
    Filed: August 8, 1997
    Date of Patent: January 11, 2000
    Assignee: Robert Bosch GmbH
    Inventors: Thomas Hallman, Heinz Goeckler, Klaus Hildebrand
  • Patent number: 5963596
    Abstract: A data processing system (10) is disclosed which comprises a microprocessor host (12) coupled to a decoding system (14). A host interface block (18) receives a bit stream and passes bit stream on to a system decoder block (20). The system decoder block (20) extracts the appropriate data from the bit stream and loads an input buffer (24) or an optional external buffer (26). An audio decoder block (28) retrieves the data from the input buffer (24) and generates scale factor indices, bit per code word values and subband samples which are stored in an arithmetic unit buffer (30). A hardware filter arithmetic unit block (32) retrieves the information from the arithmetic unit buffer (30) and dequantizes, transforms and filters the data to generate PCM output data which is loaded into a PCM buffer (34). The data within the PCM buffer (34) is output by a PCM output block (36) to a digital-to-analog converter (16).
    Type: Grant
    Filed: May 16, 1997
    Date of Patent: October 5, 1999
    Assignee: Texas Instruments Incorporated
    Inventors: Gerard Benbassat, Frank L. Laczko, Sr., Stephen H. Li, Karen L. Walker, Shiu Wai Kam
  • Patent number: 5960037
    Abstract: The apparatus for encoding a plurality of digital information signals, having at least a first input unit for receiving a first digital information signal and a second input unit for receiving a second digital information signal. A signal combination unit combines the first and second digital information signal to generate a first combination signal. First and second data compression units compress the first and second digital information signal so as to obtain first and second data reduced digital information signals. First, second, and third masked threshold determining units determine first, second and third masked thresholds respectively from the first, second digital information signals and the combination signal respectively. A selection unit selects one masked threshold from the first and third masked threshold so as to obtain a first selected masked threshold. Preferably, the first selected masked threshold is the smallest of the first and third masked thresholds.
    Type: Grant
    Filed: April 9, 1997
    Date of Patent: September 28, 1999
    Assignee: U.S. Phillips Corporation
    Inventor: Warner R.T. Ten Kate
  • Patent number: 5944842
    Abstract: A novel apparatus and method are provided for data communication over noisy media. The apparatus includes one or both of a transmitter circuit located at a transmitting location and a receiver circuit located at a receiving location. The data is encoded to provide error correction capabilities. The encoded signal is further modified by performing one or more linear mathematical operations in order to further randomize the data signal. The transmitter circuit thus generates a wideband spread spectrum signal based on the data which is to be transmitted, which spreads the signal and improves its immunity to noise. The coding used to spread the data signal may or may not be a function of the data itself. The present invention provides enhanced noise immunity without any resulting degradation in the operation and efficiency of the error correction coding.
    Type: Grant
    Filed: June 17, 1997
    Date of Patent: August 31, 1999
    Assignee: Adaptive Networks, Inc.
    Inventors: Michael B. Propp, David L. Propp
  • Patent number: 5909467
    Abstract: In a signal processing method to compress digital audio data by a block floating process, digital signal encoding/decoding apparatuses prevent deterioration of sound quality of the digital audio signal and improve the compression ratio of the digital audio signal when the digital audio signal is converted on a frequency axis per predetermined time frame, and data on the frequency axis is then divided into a plurality of blocks to be recorded, otherwise, bits are allocated per block to compress the digital audio signal for minimizing transmitted parameters. Also, encoding/decoding methods are provided to enable highly efficient encoding/decoding without recording or transmitting word length, allowing one to obtain a high-quality audio signal by allocating bits conventionally held by the word length to hold quantization data of a spectrum signal.
    Type: Grant
    Filed: June 10, 1997
    Date of Patent: June 1, 1999
    Assignee: Goldstar Co., Ltd.
    Inventor: Won Kun Tae
  • Patent number: 5841388
    Abstract: An A/D converter apparatus comprising a negative feedback loop having a main signal line supplied with an input signal of a predetermined frequency and a feedback signal line passing through a feedback signal, a A/D converter connected to the main signal line for frequency-converting the input signal to a signal having a frequency different from that of the input signal to output a converted signal, a D/A converter connected to the feedback signal line for frequency-converting the feedback signal to a signal having a frequency substantially equal to that of the input signal, and a subtracter for subtracting the feedback signal from the D/A converter from the input signal to supply a subtraction result signal to the A/D converter.
    Type: Grant
    Filed: September 13, 1995
    Date of Patent: November 24, 1998
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Akira Yasuda, Tetsuro Itakura, Takafumi Yamaji
  • Patent number: 5822367
    Abstract: A digital mobile data communication system includes a protocol converter in an exchange which simultaneously activates an FEC protocol receiver in a radio communication zone for modem communications at a rate of 2.4 Kbps and an ARQ protocol receiver in the radio communication zone for modem communications at a rate of 9.6 Kbps, and selects whichever one of the FEC protocol receiver or ARQ protocol receiver that has established receiving synchronization and the corresponding protocol transmitter.
    Type: Grant
    Filed: August 22, 1996
    Date of Patent: October 13, 1998
    Assignee: NEC Corporation
    Inventors: Katuhide Koshino, Masayuki Sakata
  • Patent number: 5802108
    Abstract: A waveform correction apparatus is disclosed. The waveform correction apparatus includes a signal generator for generating a signal; a maximal value recorder for recording a maximal value of the signal waveform; a minimal value recorder for recording a minimal value of the signal waveform; a difference value generator for generating a difference value of the maximal value and the minimal value; and a comparative controller for comparing the difference value with a reference value. The comparative controller outputs a corrected waveform when the difference value is larger than the reference value, otherwise it outputs the original waveform generated by the waveform generator. The corrected waveform is formed by shifting up or down the original waveform by a constant value.
    Type: Grant
    Filed: January 26, 1996
    Date of Patent: September 1, 1998
    Assignee: United Microelectronics Corporation
    Inventor: Chih-Kuang Kao
  • Patent number: 5784491
    Abstract: An image is vector-quantized into coded data, which is stored in a storage device. The coded data is read out of the storage device and is decoded. The decoded data may cause an overflow due to a vector quantization error. If every piece of coded data is checked for an overflow when it is decoding, a large number of processes must be carried which extends the decoding time. To solve this problem, each piece of coded data is once decoded in the vector quantization stage, to determine whether or not the coded data causes an overflow. If it is determined that it causes an overflow, the coded data is provided with exception judging information indicating that an exceptional overflow process must be carried out when decoding the coded data. As a result, the exceptional overflow process is carried out only when required in a decoding stage, to shorten a decoding time.
    Type: Grant
    Filed: February 21, 1995
    Date of Patent: July 21, 1998
    Assignee: Fujitsu Limited
    Inventor: Yuzuru Koga
  • Patent number: 5757938
    Abstract: An apparatus and method for processing an input digital signal in which an input digital audio signal at an input terminal 11 is supplied via a one-block delay unit 17 to a difference unit 20, an output of which is processed by a noise-shaping circuit 21 and restored by a near-instantaneous compressor 26, a near-instantaneous expander 27 and an accumulator 28 so as to be fed back to the difference unit 20 to find a difference between a signal of a directly preceding sample and a signal of the current sample. The noise shaping circuit 21 modifies the spectrum of the quantization noise by taking aural characteristics, such as equal-loudness characteristics or masking characteristics, into account for diminishing the level of the quantization noise as perceived by the ear. The noise level as perceived may be reduced in a manner desirable for the sound quality without changing the existing format.
    Type: Grant
    Filed: May 8, 1995
    Date of Patent: May 26, 1998
    Assignee: Sony Corporation
    Inventors: Kenzo Akagiri, Makoto Akune
  • Patent number: 5757677
    Abstract: Method and apparatus for compensating for the differences in time varying signals S(t;R;S) received and processed by two signal receivers (R.sub.2 and R.sub.3), located at the same site, from two signal sources (S.sub.2 and S.sub.3) that are spaced apart from the receivers. A receiver (R.sub.1) is chosen as a baseline, and two double difference signals DD(t;R.sub.1 ;R.sub.2 ;S.sub.2 ;S.sub.3)=S(t;R.sub.1 ;S.sub.2)-S(t;R.sub.1 ;S.sub.3)-S(t;R.sub.2 ;S.sub.2)+S(t;R.sub.2 ;S.sub.3) and DD(t;R.sub.1 ;R.sub.3 ;S.sub.2 ;S.sub.3)=S(t;R.sub.1 ;S.sub.2)-S(t;R.sub.1 ;S.sub.3)-S(t;R.sub.3 ;S.sub.2)+S(t;R.sub.3 ;S.sub.3) are formed. Time averages of these two double difference signals are formed, using a time interval of length T lying in a preferred range, and are subtracted from the corresponding double difference signals to form first and second compensated signals.
    Type: Grant
    Filed: May 31, 1996
    Date of Patent: May 26, 1998
    Assignee: Trimble Navigation Limited
    Inventor: Gary R. Lennen
  • Patent number: 5754592
    Abstract: An oversampling technique that improves signal-to-quantization noise ratio without requiring substantial amounts of processing power is disclosed. The oversampling technique determines the oversample values by successively scaling the previous value using a scaling factor. The effect of the invention is the randomize the quantization error for each of the oversample values so that the quantization error becomes uncorrelated from one oversample value to the next. When such decorrelation occurs, the quantization noise is spread over the enlarged frequency band associated with the oversampling. The invention is applicable to any transmission scheme which utilizes oversampling and digital-to-analog conversion.
    Type: Grant
    Filed: July 2, 1996
    Date of Patent: May 19, 1998
    Assignee: Amati Communications Corporation
    Inventors: Mark B. Flowers, John A. C. Bingham, Michael D. Agah
  • Patent number: 5742643
    Abstract: In digital communications over a limited-bandwidth channel such as a radio-broadcast channel, multiple phase-amplitude shift keyed (MPASK) modulation is preferred using close packed hexagonal code. In quantizing such signals, a representation of an equalized received signal is transformed such that, to each symbol of the constellation, there corresponds a respective point on a square grid. A symbol of the constellation is determined as a quantized representative of the received signal by its selection as the one or the other of two symbols of the constellation having transformed representations at vertices of the square or rectangle in which the transformed signal lies. Such quantizing can be performed at a rate which is independent of the size of the constellation, and can be combined with similarly advantageous decoding in a receiver.
    Type: Grant
    Filed: November 22, 1994
    Date of Patent: April 21, 1998
    Assignee: Mikros Systems Corporation
    Inventors: Philip J. Reeves, Harald A. Wougk
  • Patent number: 5729556
    Abstract: A data processing system (10) is disclosed which comprises a microprocessor host (12) coupled to a decoding system (14). A host interface block (18) receives a bit stream and passes bit stream on to a system decoder block (20). The system decoder block (20) extracts the appropriate data from the bit stream and loads an input buffer (24) or an optional external buffer (26). An audio decoder block (28) retrieves the data from the input buffer (24) and generates scale factor indices, bit per code word values and subband samples which are stored in an arithmetic unit buffer (30). A hardware filter arithmetic unit block (32) retrieves the information from the arithmetic unit buffer (30) and dequantizes, transforms and filters the data to generate PCM output data which is loaded into a PCM buffer (34). The data within the PCM buffer (34) is output by a PCM output block (36) to a digital-to-analog converter (16).
    Type: Grant
    Filed: April 26, 1993
    Date of Patent: March 17, 1998
    Assignee: Texas Instruments
    Inventors: Gerard Benbassat, Frank L. Laczko, Sr., Stephen H. Li, Karen L. Walker, Shiu Wai Kam
  • Patent number: 5712874
    Abstract: In a noise shaper comprising first and second cascaded integrators, a quantizer receiving an output signal of the second integrator, and a feedback path for feeding back an output of the quantizer to each of the first and second integrators, the first integrator includes an adder having a first input receiving art input signal applied to the first integrator, a delay circuit receiving an output of the adder to output a one-sample-delayed signal, and a multiplying circuit having an input connected to an output of the delay circuit for multiplying the one-sample-delayed signal outputted from the delay circuit, by a positive coefficient "0.999". An output of the multiplying circuit is connected to a second input of the adder. An output of the delay circuit constitutes the output of the first integrator.
    Type: Grant
    Filed: December 7, 1994
    Date of Patent: January 27, 1998
    Assignee: NEC Corpoation
    Inventor: Toshiyuki Okamoto
  • Patent number: 5710790
    Abstract: A modem that matches itself to a central office codec to which it is connected and incorporates encoding of the data. An echo canceller following the central office codec subtracts an estimate of the echo introduced in the central offices. More particularly, digital data applied to the modem is multi-level encoded and mapped onto a subset of the levels recognized by the central office codec. In an illustrative embodiment, the multi-level encoding encodes the two least significant bits in the binary representation of the levels delivered by the modem. The least significant bit is encoded with a code that is more robust than the code of the next-to-least significant bit, in recognition of the fact that errors in the least significant bit are much more likely. The corresponding echo canceller in the network first estimates the echo and subtracts it from the signal applied to the digital network by the central office. Thereafter, a decoder decodes the received signal in stages.
    Type: Grant
    Filed: February 1, 1995
    Date of Patent: January 20, 1998
    Assignee: Lucent Technologies Inc.
    Inventors: Hanan Herzberg, Burton Reuben Saltzberg
  • Patent number: 5699382
    Abstract: The invention is used to shape noise in time domain and frequency domain coding schemes. The method advantageously uses a noise weighting filter based on a filterbank with variable gains. A method is presented for decoding an encoded signal based on received side information and on a masking matrix derived from the masking properties of speech. In particular, the encoded signal is separated into subband signal components, each of which is multiplied by a corresponding gain value based on the masking matrix. These multiplied subband signal components are then combined to produce a decoded signal.
    Type: Grant
    Filed: November 12, 1996
    Date of Patent: December 16, 1997
    Assignee: Lucent Technologies Inc.
    Inventors: Yair Shoham, Casimir Wierzynski
  • Patent number: 5694426
    Abstract: A new signal quantization scheme is proposed which reduces fluctuation of the output signal by a signal quantizer (10) providing a quantized output signal and multiplying (18) said input signal X by a factor (1-w.sub.1) and finding a difference signal .DELTA..sub.in (11) between both the input signal and the previous input signal and multiplying (16) that by a weighting factor w.sub.2 from a control (13). The previous quantizer output signal Q.sub.prev is summed (17) with the weighted difference signal .DELTA..sub.in w.sub.2 and the sum is weighted by a weighting factor w.sub.1 at a multiplier (19) to yield w.sub.1 (Q.sub.prev +w.sub.2 .DELTA..sub.in). This signal is then summed at an adder (21) and applied to the quantizer (10) so that the quantizer is forced to match the fluctuation in the input signal as well as the signal itself.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: December 2, 1997
    Assignee: Texas Instruments Incorporated
    Inventors: Alan V. McCree, Vishu R. Viswanathan
  • Patent number: 5691714
    Abstract: In a process for the serial transmission of measurement values which are continuously supplied by a sensor and which occur at the transmitter end in digital form, to a receiver, the measurement values are ascertained at such short time intervals that their deviation from the respectively precedingly ascertained measurement value can he represented generally by only two bits of which the one reproduces the sign and the other the value of the deviation. Of the measurement values which occur within a predeterminable period of time, only a respective one is completely transmitted as an absolute value while of the others only the respective incremental alteration values which are related to the one measurement value are transmitted. At the receiver end `virtual` measurement values corresponding to the measurement values occurring at the transmitter end are synthesised by the transmitted incremental values being added, correctly in respect of value and sign, to the completely transmitted absolute value.
    Type: Grant
    Filed: December 11, 1995
    Date of Patent: November 25, 1997
    Inventors: Walter Mehnert, Thomas Theil
  • Patent number: 5677933
    Abstract: In a signal processing method to compress digital audio data by a block floating process, digital signal encoding/decoding apparatuses prevent deterioration of sound quality of the digital audio signal and improve the compression ratio of the digital audio signal when the digital audio signal is converted on a frequency axis per predetermined time frame, and data on the frequency axis is then divided into a plurality of blocks to be recorded, otherwise, bits are allocated per block to compress the digital audio signal for minimizing transmitted parameters. Also, encoding/decoding methods are provided to enable highly efficient encoding/decoding without recording or transmitting word length, allowing one to obtain a high-quality audio signal by allocating bits conventionally held by the word length to hold quantization data of a spectrum signal.
    Type: Grant
    Filed: December 6, 1994
    Date of Patent: October 14, 1997
    Assignee: Goldstar Co., Ltd.
    Inventor: Won Kun Tae
  • Patent number: 5677994
    Abstract: A high-efficiency encoding method and apparatus assuring a higher data compression ratio than with known encoding method and apparatus. The multi-channel signals including bandwidth-limited signals of at least one channel are encoded by the same encoding technique by an encoding unit. The bandwidth-limited signals of at least one channel, resulting from encoding by the encoding unit, are re-encoded by a re-encoding unit for eliminating the redundant information produced by the bandwidth limitation.
    Type: Grant
    Filed: April 11, 1995
    Date of Patent: October 14, 1997
    Assignees: Sony Corporation, Sony Cinema Products Corporation
    Inventors: Shinji Miyamori, Masatoshi Ueno
  • Patent number: 5673289
    Abstract: A method and an apparatus for encoding a digital audio signal are provided. The method comprises the steps of: mapping the digital audio signal into a plurality of sub-bands and outputting the mapped sub-band signals; allocating a number of bits to each sub-band signal according to human psychoacoustic properties, on the basis of the mapped sub-band signals; compensating each sub-band signal by receiving a transmitted previous quantized error, quantizing the compensated sub-band signals according to the corresponding allocated bit number, and transferring the current quantized error to the next quantization; and forming a transmit bit stream in frame units from the quantized data. Therefore, the quantized error generated during encoding of the audio signal is can be minimized.
    Type: Grant
    Filed: December 21, 1994
    Date of Patent: September 30, 1997
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Sang-wook Kim, Yeon-bae Kim, Yang-seock Seo
  • Patent number: 5654760
    Abstract: A video image encoder estimates a quantization noise curve which will result from quantizing a coefficient data block and uses the estimated quantization noise curve and a specified minimum noise value to select the quantization step size actually used to quantize the coefficient data block. The quantization step size is also selected as a function of transmission buffer occupancy so as to limit the amount of encoded data to a predetermined rate.
    Type: Grant
    Filed: March 27, 1995
    Date of Patent: August 5, 1997
    Assignee: Sony Corporation
    Inventor: Tomoyuki Ohtsuki
  • Patent number: 5646961
    Abstract: The invention is used to shape noise in time domain and frequency domain coding schemes. The method advantageously uses a noise weighting filter based on a filterbank with variable gains. A method is presented for computing the gains in the noise weighting filterbank with filter parameters derived from the masking properties of speech. Illustrative embodiments of the method in various coding schemes are illustrated.
    Type: Grant
    Filed: December 30, 1994
    Date of Patent: July 8, 1997
    Assignee: Lucent Technologies Inc.
    Inventors: Yair Shoham, Casimir Wierzynski
  • Patent number: 5642383
    Abstract: An audio data coding method of requantizing digital audio data in accordance with the hearing sense characteristic of the human being, comprises: the steps of calculating a quantization error; calculating a level correction value from the calculated quantization error and a level of an input signal; and carrying out level correction of the digital audio data in accordance with the level correction value. In addition, there is provided an audio data coding apparatus for implementing the above-mentioned audio data coding method.
    Type: Grant
    Filed: July 19, 1996
    Date of Patent: June 24, 1997
    Assignee: Sony Corporation
    Inventor: Hiroshi Suzuki
  • Patent number: 5610943
    Abstract: The present invention provides a two-system A/D converter, which provides a digital output signal with a higher conversion precision than is achieved by a single-system A/D converter. Conversely, by using a two-system D/A converter with a lower conversion precision, the present invention provides an analog output signal with a higher conversion precision than is achieved by a single-system D/A converter. Further, a digital signal clock changing unit produces data by performing high sampling of the first digital data trains, and the second digital data is synchronized with a second clock through an interpolation processing based on the timing difference between the first and second clocks. A high-precision A/D and D/A converter apparatus is thus realized by using two pulse code modulation coder/decoders (PCM.CODECs) and one digital signal processor (DSP).
    Type: Grant
    Filed: May 8, 1995
    Date of Patent: March 11, 1997
    Assignee: Fujitsu Limited
    Inventors: Mitsuo Kakuishi, Tsuyoshi Ueshima
  • Patent number: 5602874
    Abstract: In a quantization noise reduction circuit (200), a feedback signal (W)is added to an input signal (X) to the quantization circuit to reduce quantization noise. The feedback signal is generated as a filtered difference between a sample of a N bit signal (X') and a time coincident sample of a M bit quantized signal, where M<N. The feedback signal is subtracted from the input signal (X) prior to quantization thereby introducing out of band noise into the input signal for reducing in band noise in the quantized signal (Y).
    Type: Grant
    Filed: February 14, 1995
    Date of Patent: February 11, 1997
    Assignee: Motorola, Inc.
    Inventors: Yuda Y. Luz, James F. Long
  • Patent number: 5568514
    Abstract: A new signal quantization scheme is proposed which reduces fluctuation of the output signal by a signal quantizer (10) providing a quantized output signal and multiplying (18) said input signal X by a factor (1-w.sub.1)and finding a difference signal .DELTA..sub.in (11) between both the input signal and the previous input signal and multiplying (16) that by a weighting factor w.sub.2 from a control (13). The previous quantizer output signal Q.sub.prev is summed (17) with the weighted difference signal .DELTA..sub.in w.sub.2 and the sum is weighted by a weighting factor w.sub.1 at a multiplier (19) to yield w.sub.1 (Q.sub.prev +w.sub.2 .DELTA..sub.in). This signal is then summed at an adder (21) and applied to the quantizer (10) so that the quantizer is forced to match the fluctuation in the input signal as well as the signal itself.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: October 22, 1996
    Assignee: Texas Instruments Incorporated
    Inventors: Alan V. McCree, Vishu R. Viswanathan
  • Patent number: 5563913
    Abstract: An apparatus and method for processing an input digital signal in which an input digital audio signal at an input terminal 11 is supplied via a one-block delay unit 17 to a difference unit 20, an output of which is processed by noise-shaping circuit 21 and restored by a near-instantaneous compressor 26, a near-instantaneous expander 27 and an accumulator 28 so as to be fed back to the difference unit 20 to find a difference between a signal of a directly preceding sample and a signal of the current sample. The noise shaping circuit 21 modifies the spectrum of the quantization noise by taking aural characteristics, such as equal-loudness characteristics or masking characteristics, into account for diminishing the level of the quantization noise as perceived by the ear. The noise level as perceived may be reduced in a manner desirable for the sound quality without changing the existing format.
    Type: Grant
    Filed: October 28, 1993
    Date of Patent: October 8, 1996
    Assignee: Sony Corporation
    Inventors: Kenzo Akagiri, Makoto Akune
  • Patent number: 5555273
    Abstract: Quantizing section 1 input audio signal data with a quantizing step width. First predicting section 14 predicts a quantization step width to be supplied to the quantizing section on the basis of the input audio signal and a number of bits of quantized data. Second predicting section 15 predicts the quantization step width on the basis of the input audio signal and a number of bits of quantized data. Coding section 2 performs Huffman coding on the quantized data. Calculating section 3 calculates the number of bits per unit time of the coded sequence signal. Selecting section 16 selects either one of the first and second predicting sections 14 and 15 on the basis of the input audio signal and the number of bits of quantized data. The first predicting section 14 further predicts another wider quantizing step width by a predetermined step width when the number of bits calculated is exceeded a predetermined value B.
    Type: Grant
    Filed: December 21, 1994
    Date of Patent: September 10, 1996
    Assignee: NEC Corporation
    Inventor: Toshiyuki Ishino
  • Patent number: 5537440
    Abstract: The present invention provides a transcoder for transcoding of digitally encoded bit streams produced by predictive encoders. The transcoder of this invention is less complex than previously known transcoders in terms of both computational and storage requirements. This efficiency is achieved by combining decoding and re-encoding steps into one step. This one-step transcoding is accomplished by modifying the originally quantized vectors and then requantizing and noiseless encoding these vectors into a bit stream in accordance with a predetermined objective.
    Type: Grant
    Filed: January 7, 1994
    Date of Patent: July 16, 1996
    Assignee: Motorola, Inc.
    Inventors: M. Vedat Eyuboglu, Mei Yong
  • Patent number: 5526291
    Abstract: A method for compensating for the differences in time varying signals S(t;R;S) received and processed by two signal receiver/processors (R.sub.2 and R.sub.3), located at the same site, from two signal sources (S.sub.2 and S.sub.3) that are spaced apart from the receiver/processors. A receiver/processor (R.sub.1) is chosen as a baseline, and double difference signals DD(t;R.sub.1 ;R.sub.2 ;S.sub.2 ;S.sub.3)=S(t;R.sub.1 ;S.sub.2)-S(t;R.sub.1 ;S.sub.3)-S(t;R.sub.2 ;S.sub.2)+S(t;R.sub.2 ;S.sub.3) and DD(t;R.sub.1 ;R.sub.3 ;S.sub.2 ;S.sub.3)=S(t;R.sub.1 ;S.sub.2)-S(t;R.sub.1 ;S.sub.3)-S(t;R.sub.3 ;S.sub.2)+S(t;R.sub.3 ;S.sub.3) are formed. The respective time averages DD(R.sub.1 ;R.sub.2 ;S.sub.2 ;S.sub.3).sub.avg and DD(R.sub.1 ;R.sub.3 ;S.sub.2 ;S.sub.3).sub.avg of these two double difference signals are formed, using a time interval of length T lying in a preferred range given by 120 sec.ltoreq.T.ltoreq.1800 sec. First difference signals, DDC(t;R.sub.1 ;R.sub.2 ;S.sub.2 ;S.sub.3)=DD(t;R.sub.1 ;R.sub.2 ;S.sub.
    Type: Grant
    Filed: September 8, 1994
    Date of Patent: June 11, 1996
    Assignee: Trimble Navigation Limited
    Inventor: Gary R. Lennen
  • Patent number: 5515395
    Abstract: In quantizing a digital signal in respective frequency bands by quantization units and transmitting (transmitting or recording) such quantized digital signal, second quantization accuracy information indicating a difference between first quantization accuracy information serving as a reference and actual quantization accuracy information from a quantization accuracy determination unit is coded at a quantization accuracy information coding unit to transmit the coded quantization accuracy information to thereby realize efficient coding while maintaining a degree of freedom in the manner of giving quantization accuracy. Accordingly, more efficient coding can be attained while leaving the degree of freedom in the manner of giving quantization accuracy by a lesser number of bits.
    Type: Grant
    Filed: December 27, 1993
    Date of Patent: May 7, 1996
    Assignee: Sony Corporation
    Inventor: Kyoya Tsutsui
  • Patent number: 5511094
    Abstract: A signal processor for a sub-band coding system includes a selector receiving various data, i.e., sample data, allocation information, synchronization and system information during encoding, changing the various data into appropriate forms for efficient encoding the various data and generating same, a memory temporarily storing various data received from the selector, an operator for selectively scaling and quantizing sample data and dequantizing and descaling encoded data, classifier providing outputting the operated data, allocation information input to the operating means, and system information as encoded data in accordance with the frame format of a general sub-band coding system, or receiving and classifying the encoded data into system information, allocation information and operated data, and a control signal generator for generating control signals for controlling the encoding and decoding of the selector, memory, operator and classifier circuits.
    Type: Grant
    Filed: April 8, 1994
    Date of Patent: April 23, 1996
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Suk-jeong Lee, Hyung-nam Byeon
  • Patent number: 5487087
    Abstract: A new signal quantization scheme is proposed which reduces fluctuation of the output signal by a signal quantizer (10) providing a quantized output signal and multiplying(18) said input signal X by a factor (1-w.sub.1)and finding a difference signal .DELTA..sub.n (11) between both the input signal and the previous input signal and multiplying (16) that by a weighting factor w.sub.2 from a control (13). The previous quantizer output signal Q.sub.prev is summed (17) with the weighted difference signal .DELTA..sub.in w.sub.2 and the sum is weighted by a weighting factor w.sub.1 at a multiplier (19) to yield w.sub.1 (Q.sub.prev +w.sub.2 .DELTA..sub.in). This signal is then summed at an adder (21) and applied to the quantizer (10) so that the quantizer is forced to match the fluctuation in the input signal as well as the signal itself. When applied to speech encoding algorithms such as the North American digital cellular telephone standard VSELP, the new quantizer results in more natural sounding background noise.
    Type: Grant
    Filed: May 17, 1994
    Date of Patent: January 23, 1996
    Assignee: Texas Instruments Incorporated
    Inventors: Alan V. McCree, Vishu R. Viswanathan
  • Patent number: 5487086
    Abstract: Before transmitting signals to a receiver, the signals are subjected to adaptive prediction to generate a residual signal for transmission, and the residual signal is then transformed into frequency domain coefficients, the coefficients are grouped together to form vectors, and the vectors are then quantized.
    Type: Grant
    Filed: September 13, 1991
    Date of Patent: January 23, 1996
    Assignee: Comsat Corporation
    Inventor: B. R. Udaya Bhaskar
  • Patent number: 5479446
    Abstract: A channel estimation device receives at one end of the channel a training sequence corresponding to a learning sequence produced at the other end of the channel. The estimation device generates a replica of the learning sequence and establishes the correlation of the learning and training sequences in order to produce a set of correlation coefficients. The estimation device includes a corrector device for eliminating the coefficients having the lowest moduli. The criteria used for eliminating the lowest moduli coefficients is that the sum of the squares of the moduli of the eliminated coefficients is less than a fraction of the sum of the squares of the moduli of all the correlation coefficients.
    Type: Grant
    Filed: September 29, 1993
    Date of Patent: December 26, 1995
    Assignee: Alcatel N.V.
    Inventor: Christophe Mourot
  • Patent number: 5469474
    Abstract: As a selected subband signal, selected is one of frequency band signals of an input signal that has a maximal signal to mask ratio. The selected subband signal is assigned, as a primary provisional bit number, with a maximal quantization bit number allocatable thereto. A primary mask to noise ratio of the selected subband signal is calculated. Other subband signals are assigned with temporary bit numbers incremented one by one from zero with secondary mask to noise ratios of the other subband signal meanwhile calculated each time when the temporary bit numbers are incremented by one. The temporary bit numbers are allocated to the other subband signals as secondary provisional bit numbers when the secondary mask to noise ratios individually exceed the primary mask to noise ratio. Some of the secondary provisional bit numbers may be equal to zero. A sum of the primary and the secondary provisional bit numbers is compared with a total of quantization bit numbers allocatable to the frequency band signals.
    Type: Grant
    Filed: June 24, 1993
    Date of Patent: November 21, 1995
    Assignee: NEC Corporation
    Inventor: Osamu Kitabatake
  • Patent number: 5461641
    Abstract: A Decimation filter for converting a train of sigma-delta pulses S(i) in synchronism with a sigma-delta clock (fs) into a train of Pulse Coded Modulation (PCM) samples in accordance with the formula ##EQU1## where Cn is the sequence of the coefficients of the decimation filter which corresponds to a determined decimation factor, and the PCM samples being processed by a Digital Signal Processor (DSP). The decimation filter includes a device for storing a digital value representative of the DC component introduced during the sigma-delta coding process, with the digital value being computing by the DSP processor during an initialization phase. The decimation filter further includes a device operating after the latter initialization phase for subtracting the stored digital value from each of the PCM samples so that the resulting sequence of PCM samples appears free of any DC component introduced during the sigma-delta coding.
    Type: Grant
    Filed: November 23, 1992
    Date of Patent: October 24, 1995
    Assignee: International Business Machines Corporation
    Inventors: Jean-Claude Abbiate, Alain Blanc, Patrick Jeanniot, Gerard Richter
  • Patent number: 5440593
    Abstract: The present invention relates to a method of aligning and blending input digital samples, comprised of delaying the input samples by a clock pulse, to provide delayed data samples, subtracting a smaller fractional part from a larger fractional part of either an input sample number and a requested sample number to provide a sample difference number first factor, subtracting the sample difference number from 1 to provide a second factor, multiplying either of the input samples or the delayed samples by the first factor to provide a first result, multiplying the other of the input samples or the delayed samples by the second factor to provide a second result, and adding the results to provide output samples.
    Type: Grant
    Filed: September 30, 1993
    Date of Patent: August 8, 1995
    Assignee: ATI Technologies Inc.
    Inventor: Pasquale Leone