Patents by Inventor Sreen A. Raghavan

Sreen A. Raghavan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8447000
    Abstract: A receiver that easily receives signals from transmission channels having long cable lengths is presented. The receiver includes an analog pre-filter that removes distortions and intersymbol interference from a predetermined transmission channel. The analog pre-filter is coupled with a digital receiver that provides digital equalization. The combination of analog equalization with digital equalization allows for simplified digital equalization while retaining the versatility of digital signal processing.
    Type: Grant
    Filed: January 12, 2009
    Date of Patent: May 21, 2013
    Assignee: National Semiconductor Corporation
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Publication number: 20120183025
    Abstract: A receiver that easily receives signals from transmission channels having long cable lengths is presented. The receiver includes an analog pre-filter that removes distortions and intersymbol interference from a predetermined transmission channel. The analog pre-filter is coupled with a digital receiver that provides digital equalization. The combination of analog equalization with digital equalization allows for simplified digital equalization while retaining the versatility of digital signal processing.
    Type: Application
    Filed: January 12, 2009
    Publication date: July 19, 2012
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Patent number: 8005135
    Abstract: An analog equalizer (613 and 614) adaptively equalizes an input analog signal affected with intersymbol interference (“ISI”), or an intermediate analog signal generated therefrom, to produce a filtered partially equalized analog signal with reduced ISI. An analog-to-digital converter (210) converts the filtered analog signal, or an intermediate analog signal generated therefrom, into an initial digital signal. A digital equalizer (212) adaptively equalizes the initial digital signal, or an intermediate digital signal generated therefrom, to produce an equalized digital signal as a stream of equalized digital values with further reduced ISI. An output decoder (605) decodes the equalized digital values, or intermediate digital values generated therefrom, into a stream of symbols.
    Type: Grant
    Filed: December 21, 2009
    Date of Patent: August 23, 2011
    Assignee: National Semiconductor Corporation
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Patent number: 7756228
    Abstract: Analog echo-cancelling circuitry (611 and 627) operates on an input analog signal that includes an echo of an output signal, or on an analog signal generated from the input signal, to produce an analog signal with reduced echo. An analog-to-digital converter (210) converts the echo-reduced analog signal, or an analog signal generated therefrom, into a digital signal. Digital echo-cancelling circuitry (615 and 621) operates on the digital signal, or on a digital signal generated therefrom, to produce a digital signal with further reduced echo. An output decoder (605) decodes the echo-reduced digital signal, or a digital signal generated therefrom, into a stream of symbols. The echo-filtering characteristics of both echo-cancelling circuitries are typically adaptively adjusted during generation of the symbol stream. The analog echo-filtering characteristics may be adapted in response to information provided by operating on the echo-reduced digital signal or on a digital signal generated therefrom.
    Type: Grant
    Filed: October 2, 2006
    Date of Patent: July 13, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Patent number: 7664172
    Abstract: A receiver system contains an analog pre-filter (207 or 619), an analog-to-digital converter (210), a digital equalizer (212), and a decoder (605) arranged sequentially for processing an input analog signal (yk). The pre-filter produces a filtered analog signal (Zs) with reduced intersymbol interference. The converter provides analog-to-digital signal conversion. Digital equalization circuitry in the equalizer operates according to a transfer frmnction c - 1 ? z + c 0 + ? M i = 1 ? c i ? z - i to produce an equalized digital signal (a'k) as a stream of equalized digital values. Coefficients c?1 and c0 are fixed. Each other coefficient ci is adaptively chosen. The decoder converts the equalized digital values, or intermediate values generated therefrom, into a stream of symbols.
    Type: Grant
    Filed: August 15, 2006
    Date of Patent: February 16, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Patent number: 7646807
    Abstract: An analog equalizer (613 and 614) adaptively equalizes an input analog signal affected with intersymbol interference (“ISI”), or an intermediate analog signal generated therefrom, to produce a filtered partially equalized analog signal with reduced ISI. An analog-to-digital converter (210) converts the filtered analog signal, or an intermediate analog signal generated therefrom, into an initial digital signal. A digital equalizer (212) adaptively equalizes the initial digital signal, or an intermediate digital signal generated therefrom, to produce an equalized digital signal as a stream of equalized digital values with further reduced ISI. An output decoder (605) decodes the equalized digital values, or intermediate digital values generated therefrom, into a stream of symbols.
    Type: Grant
    Filed: July 19, 2006
    Date of Patent: January 12, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Patent number: 7613234
    Abstract: A transceiver according to the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter and includes an interference filter for correcting for interference from transmitters other than the complementary transmitter. The interference filter, for example, can correct for near-end cross-talk and echo interference filtering and/or far-end crosstalk interference filtering is presented. A transceiver can include a transmitter portion and a receiver portion with one or more receivers coupled to receives signals in the plurality of frequency separated transmission channels. A baseband transmitter can be combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands).
    Type: Grant
    Filed: April 4, 2008
    Date of Patent: November 3, 2009
    Assignee: Entropic Communications, Inc.
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Patent number: 7590168
    Abstract: A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels. A transmitter system and a receiver system are described for the communication system.
    Type: Grant
    Filed: September 26, 2001
    Date of Patent: September 15, 2009
    Assignee: Entropic Communications, Inc.
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway
  • Publication number: 20080285634
    Abstract: A transceiver according to the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter and includes an interference filter for correcting for interference from transmitters other than the complementary transmitter. The interference filter, for example, can correct for near-end cross-talk and echo interference filtering and/or far-end crosstalk interference filtering is presented. A transceiver can include a transmitter portion and a receiver portion with one or more receivers coupled to receives signals in the plurality of frequency separated transmission channels. A baseband transmitter can be combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands).
    Type: Application
    Filed: April 4, 2008
    Publication date: November 20, 2008
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Patent number: 7403752
    Abstract: A transceiver system according to the present invention transmits data utilizing the baseband and one or more frequency separated transmission bands. A baseband transmitter is combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. A baseband receiver is combined with one or more receivers that receive data from the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands). A transceiver circuit or chip according to the present invention includes a transmitter and a receiver and communicates with a corresponding transceiver chip. In some embodiments, one baseband PAM transmitter is combined with one frequency separated QAM transmitter.
    Type: Grant
    Filed: December 4, 2002
    Date of Patent: July 22, 2008
    Assignee: Vativ Technologies, Inc.
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Patent number: 7388904
    Abstract: A transceiver according to the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter and includes an interference filter for correcting for interference from transmitters other than the complementary transmitter. The interference filter, for example, can correct for near-end cross-talk and echo interference filtering and/or far-end crosstalk interference filtering is presented. A transceiver can include a transmitter portion and a receiver portion with one or more receivers coupled to receives signals in the plurality of frequency separated transmission channels. A baseband transmitter can be combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands).
    Type: Grant
    Filed: June 3, 2003
    Date of Patent: June 17, 2008
    Assignee: Vativ Technologies, Inc.
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Patent number: 7254198
    Abstract: A receiver system suitable for a local area network contains an analog pre-filter (207 or 619), an analog-to-digital converter (210), a digital equalizer (212), and a decoder (605). A symbol-information-carrying input analog signal (yk), or a first intermediate analog signal generated from the input analog signal, is filtered by filtering circuitry in the pre-filter to produce a filtered analog signal (Zs) with reduced intersymbol interference. The filtering circuitry operates according to a transfer function such as (b1s+1)/(a2s2+a1s+1) or (1?Vc)+VcPF(s) where Vc is adaptively varied. The analog-to-digital converter provides analog-to-digital signal conversion. The equalizer provides digital signal equalization to produce an equalized digital signal (a?k) as a stream of equalized digital values. The decoder converts the equalized digital values, or intermediate digital values generated from the equalized digital values, into a stream of symbols.
    Type: Grant
    Filed: April 28, 2000
    Date of Patent: August 7, 2007
    Assignee: National Semiconductor Corporation
    Inventors: Tulsi Manickam, Peter J. Sallaway, Sreen A. Raghavan, Abhijit M. Phanse, James B. Wieser
  • Patent number: 7248890
    Abstract: A transceiver according to some embodiments of the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter of another transceiver and adjusts the power output of certain channels in a transmitter of the receiver. Upon start-up, the power output levels of signals in individual channels in the transmitter can be preset. A power balance can determine new power output levels of the transmitter from parameters in the receiver while receiving data transmitted by a similarly situated complementary transmitter in a second transceiver coupled to the transceiver. In some embodiments, a complementary receiver of the other transceiver determines the power outputs of the transmitter and the power levels are transmitted to the transmitter by the other transceiver.
    Type: Grant
    Filed: February 6, 2004
    Date of Patent: July 24, 2007
    Assignee: Vativ Technologies, Inc.
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Patent number: 7236757
    Abstract: A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. Additionally, a cross-channel interference filter in a receiver section corrects for cross-channel interference in the communication system. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels. A transmitter system and a receiver system are described for the communication system.
    Type: Grant
    Filed: February 6, 2002
    Date of Patent: June 26, 2007
    Assignee: Vativ Technologies, Inc.
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Publication number: 20040247022
    Abstract: A transceiver according to the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter and includes an interference filter for correcting for interference from transmitters other than the complementary transmitter. The interference filter, for example, can correct for near-end cross-talk and echo interference filtering and/or far-end crosstalk interference filtering is presented. A transceiver can include a transmitter portion and a receiver portion with one or more receivers coupled to receives signals in the plurality of frequency separated transmission channels. A baseband transmitter can be combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands).
    Type: Application
    Filed: June 3, 2003
    Publication date: December 9, 2004
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Publication number: 20030112896
    Abstract: A transceiver system according to the present invention transmits data utilizing the baseband and one or more frequency separated transmission bands. A baseband transmitter is combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. A baseband receiver is combined with one or more receivers that receive data from the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands). A transceiver circuit or chip according to the present invention includes a transmitter and a receiver and communicates with a corresponding transceiver chip. In some embodiments, one baseband PAM transmitter is combined with one frequency separated QAM transmitter.
    Type: Application
    Filed: June 10, 2002
    Publication date: June 19, 2003
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Publication number: 20030087634
    Abstract: A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. Additionally, a cross-channel interference filter in a receiver section corrects for cross-channel interference in the communication system. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels. A transmitter system and a receiver system are described for the communication system.
    Type: Application
    Filed: February 6, 2002
    Publication date: May 8, 2003
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway, Gerard E. Taylor
  • Publication number: 20030081693
    Abstract: A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels. A transmitter system and a receiver system are described for the communication system.
    Type: Application
    Filed: September 26, 2001
    Publication date: May 1, 2003
    Inventors: Sreen A. Raghavan, Thulasinath G. Manickam, Peter J. Sallaway
  • Patent number: 6438163
    Abstract: A receiver that calculates the length of the transmission channel cable based on the receiver parameters is presented. The cable length is calculated based on the gain of an automatic gain control circuit or is based on the multiplier coefficients of an equalizer of the receiver. A comparison between a cable length calculated using the gain from the automatic gain control circuit and a cable length calculated using the multiplier coefficients of the equalizer indicates the quality of the cable.
    Type: Grant
    Filed: September 25, 1998
    Date of Patent: August 20, 2002
    Assignee: National Semiconductor Corporation
    Inventors: Sreen A. Raghavan, Doug J Easton
  • Patent number: 6421381
    Abstract: A 100Base-TX detection system is presented which takes advantage of the form of the frequency response of the channel to provide a simplified filter for producing an output signal with reduced distortion. Utilizing the nature of the frequency response function of category-5 twisted pair cabling, a finite impulse response linear equalizer or an infinite impulse response decision feedback equalizer having as few as two multipliers is implemented.
    Type: Grant
    Filed: July 20, 2000
    Date of Patent: July 16, 2002
    Assignee: National Semiconductor Corporation
    Inventor: Sreen A. Raghavan