Patents by Inventor Thomas Holtzman Williams

Thomas Holtzman Williams 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: 7415367
    Abstract: A system and method to range a distance to a source of CPD (Common Path Distortion) on a two-way cable system, comprising a local CPD source and a cross-correlator. The local CPD source generates a local distortion signal from a downstream signal, wherein the downstream signal includes multiple carriers of TV channels. The source of CPD in the cable system mixes the carriers of the TV channels to create an upstream actual distortion signal. The cross-correlator performs a cross-correlation between the local distortion signal and the upstream actual distortion signal to create a cross-correlation plot, and the distance to the source of CPD is determined from the round-trip time.
    Type: Grant
    Filed: May 20, 2004
    Date of Patent: August 19, 2008
    Assignee: Arcom Digital, LLC
    Inventor: Thomas Holtzman Williams
  • Publication number: 20070286308
    Abstract: This invention describes a system and a method to generate a modulated signal of an arbitrary angle and magnitude using two equal constant-amplitude carrier waves, each with adjustable-phase angles. The modulated signal is vector sum is created by combining the first carrier wave with the second carrier wave, where the phase angles of the first and second carrier waves determines both the magnitude and the phase of the desired modulated signal The necessary phase angle adjustment of the first and the second carrier waves can be achieved by rapidly reprogramming numerically controlled oscillators (NCOs), which are also known as direct digital synthesis (DDS) signal generators. This technique eliminates the inefficiency of conventional linear amplifiers and allows a single transmitter to efficiently generate signals with multiple modulation types. This technique also eliminates conventional modulators, which convert baseband signals into radio frequency signals.
    Type: Application
    Filed: June 12, 2006
    Publication date: December 13, 2007
    Inventor: Thomas Holtzman Williams
  • Publication number: 20040245995
    Abstract: Common path distortion (CPD) is an impairment that afflicts two-way cable systems. Point contact diodes caused by metallic corrosion in the plant mix downstream signals. Some of the mixing products fall into an upstream frequency band where they interfere with upstream signals. A good way to locate the sources of CPD is to use a system that ranges the distance to source of CPD. One prior art system uses custom-built software and hardware, injects test signals into the downstream signal path, and looks for resulting mixing products on the upstream signal path. Unfortunately, some cable systems do not have any available vacant bandwidth for testing. Digital downstream signals, which are already being carried on the plant, can be used for testing by mixing them at the test location to create a local distortion signal. The local distortion signal may be processed with an actual distortion signal using cross-correlation to range a distance to a source of CPD.
    Type: Application
    Filed: May 20, 2004
    Publication date: December 9, 2004
    Inventor: Thomas Holtzman Williams
  • Publication number: 20040091055
    Abstract: A digital modulation technique that utilizes a spreading matrix to linearly transform an input symbol sequence into a transmit symbol sequence using a two-dimensional transmission matrix. The transmit symbol sequence is filtered, modulated, and transmitted over a channel. At the receiver, a received symbol sequence is captured, demodulated, equalized if needed, and again transformed with a recovery matrix that is an inverse of the spreading matrix that was used at the transmitter. By using an inverse matrix instead of a more conventional transposed matrix, it is possible to construct a matrix from non-orthogonal basis functions. This allows much greater flexibility in determining the properties of a transmitted symbol sequence. If a non-square transmission matrix is used, the number of symbols in the transmit symbol sequence may exceed the number of symbols in the input symbol sequence, creating redundant symbols.
    Type: Application
    Filed: October 30, 2003
    Publication date: May 13, 2004
    Inventor: Thomas Holtzman Williams