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: 6418172
    Abstract: A Nearest Neighbors Look-Ahead Maximum Likelihood Estimation Sequence (LA-MLSE) algorithm for decoding data in a digital communications system forms the following three vectors to decode data: (1) a vector of the encoder input bit signals A=A{k, k+1, k+2}, (2) a vector of the noise-free encoder channel output signals Y=Y{A(k), A(k+1), A(k+2)}; and (3) a vector of the received signals R=R(A(k), A(k+1), A(k+2)). If the distance between the received signal R and at least one of the channel output vectors which are of the form Y{1, A(k+1), A(k+2)} is shorter than the distance between the received signal R and the Nearest Neighbor of the signal Y{1, A(k+1), A(k+2)}, then A(k) is decoded as 1.
    Type: Grant
    Filed: April 21, 1999
    Date of Patent: July 9, 2002
    Assignee: National Semiconductor Corporation
    Inventors: Sreen A. Raghavan, Hari Thirumoorthy
  • Patent number: 6415003
    Abstract: In a data communications system, a digitally implemented correction for baseline wander and the receipt of killer packets resulting from coupling transformers in the transmission channel is presented. The baseline wander correction is accomplished in a feedback loop that does not depend on models of the coupling transformers between the transmitter and the transport media and the receiver and the transport media. Additionally, a digital response to killer packets is presented that does not require the use of higher resolution analog-to-digital converters and does not require the use of a lower resolution in the analog-to-digital converter of the receiver. Instead, the reference voltage of the analog-to-digital converter is adjusted for short cables, where killer packets are a problem.
    Type: Grant
    Filed: September 11, 1998
    Date of Patent: July 2, 2002
    Assignee: National Semiconductor Corporation
    Inventor: Sreen A. Raghavan
  • Patent number: 6115418
    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: February 9, 1998
    Date of Patent: September 5, 2000
    Assignee: National Semiconductor Corporation
    Inventor: Sreen A. Raghavan
  • Patent number: 6038269
    Abstract: A new detection system that improves the detection signal-to-noise (SNR) ratio of a digital communication system suffering from intersymbol interference is described. The detection system utilizes the sample power contained in the intersymbol interference created by the dispersive nature of the communication channel. Significant SNR advantages over more commonly used decision-feedback equalizers (DFE) and linear equalizers are realized.
    Type: Grant
    Filed: November 20, 1997
    Date of Patent: March 14, 2000
    Assignee: National Semiconductor Corporation
    Inventor: Sreen A. Raghavan