Steven A Tretter, 84601 Hawkesbury Ter, Silver Spring, MD 20904

7133809, Nov 7, 2006

Apr 4, 2000

09/542222

Aleksandar Purkovic - Potomac MD, US
Steven A. Tretter - Silver Spring MD, US

Nortel Networks Ltd

G06F 17/10

703 2, 703 13, 703 14, 703 21, 375231, 375232

A system, device, and method for time-domain equalizer training uses a two-pass auto-regressive moving average model. A communication channel is first modeled using ppoles and qzeros to form a first shortened channel impulse response having a first approximation H(z)=B(z)/1+A(z), wherein q, is greater than a predetermined cyclic prefix length. A time-mirrored image of the first shortened channel impulse response is then formed, and the resulting time-mirrored image of the first shortened channel impulse response is modeled using ppoles and qzeros to form a second shortened channel impulse response having a second approximation H(z)=B(z)/1+A(z), wherein qis less than or equal to the predetermined cyclic prefix length. The time-domain equalizer coefficients are determined by combining A(z) and A(1/z) with an appropriate amount of delay.

8601355, Dec 3, 2013

May 27, 2009

12/472719

Aleksandar Purkovic - Potomac MD, US
Brian Francis Johnson - Kensington MD, US
Slobodan Jovanovic - Bethesda MD, US
Steven Alan Tretter - Silver Spring MD, US

Texas Instruments Incorporated - Dallas TX

H03M 13/03

714796

A decoding circuit, is provided, comprising: a turbo decoder configured to receive a input systematic bit soft information values and input parity bit information values, and to generate output systematic bit soft information values and hard decoded bits according to a turbo decoding operation; and a parity bit soft information generation circuit configured to receive the input systematic bit soft information values, the input parity bit soft information values, and the output systematic bit soft information values; to determine initial forward metrics, initial backward metrics, and branch metrics as a function of the input parity bit soft information values and the output systematic bit soft information values; to determine output parity bit soft information values based on the branch metrics, the initial forward metrics, and the initial backward metrics; and to provide the output parity bit soft information values as a signal output.

2001003, Oct 25, 2001

Apr 20, 2001

09/838318

Christian Rieser - Middletown MD, US
Jerome Gansman - Silver Spring MD, US
Gilmer Blankenship - Washington DC, US
Steven Tretter - Silver Spring MD, US
Adrianos Papamarcou - Washington DC, US

University of Maryland, College Park.

H04M011/00

455/404000, 455/456000, 455/067100

A method and system are provided for sending location dependent and personal identification information to a public safety answering point. Base stations for receiving a transmission packet signal having a transmitter identification number are located throughout an area where personal security coverage is desired. Whenever a personal security transmitter is activated, it is received by one or more base stations. Each base station has a signal receiving unit for receiving a transmission packet signal and a signal processing unit for processing a transmission packet signal and generating a base station packet. Base station packets contain both a transmitter identification number and location information about the activated transmitter. After a base station packet is generated, it is sent to a command center for processing. If a valid base station packet is received at a command center, information contained in the base station packet is used to determine the closest base station to the activated transmitter and to retrieve personal identification information about the person to whom the transmitter was issued. This location and personal identification information is then displayed at the command center or public safety answering point.

5091953, Feb 25, 1992

Feb 13, 1990

7/479466

Steven A. Tretter - Silver Spring MD

University of Maryland at College Park - College Park MD

G10K 1116

351 71

Repetitive phenomena cancelling controller arrangement for cancelling unwanted repetitive phenomena comprising known fundamental frequencies. The known frequencies are determined and an electrical known frequency signal corresponding to the known fundamental frequencies of the unwanted repetition phenomena is generated. A plurality of sensors are employed in which each sensor senses residual phenomena and generates an electrical residual phenomena signal representative of the residual phenomena. A plurality of actuators are provided for cancelling phenomena signals at a plurality of locations, and a controller is utilized for automatically controlling each of the actuators as a predetermined function of the known fundamental frequencies of the unwanted repetitive phenomena and of the residual phenomena signals from the plurality of sensors. In this arrangement the plurality of actuators operate to selectively cancel discrete harmonics of the known fundamental frequencies while accommodating interactions between the various sensors and actuators.

4873701, Oct 10, 1989

Sep 16, 1987

7/097448

Steven A. Tretter - Silver Spring MD

Penril Corporation - Rockville MD

H04B 1406

375 27

A modem and method for modulation-demodulation of a received analog signal. The modem receives sixteen bits at four bits per baud. The 8 D Block Encoder encodes nine of the sixteen bits into 12 Z-bits which are used to specify a sequence of four 2 D constellation points. These 2 D constellation points correspond to a sequence of four 2 D subsets of a 8 D subtype selected. The differential encoder differentially encodes two of the sixteen bits to make the code transparent to a 90 degree rotation. The rate 3/4 convolutional encoder generates a check bit and a bit converter converts the check bit, the differential encoded bits and the remaining five bits into 8 Z-bits. The result is an 8 D trellis with a 20-point 2 D constellation.

5388124, Feb 7, 1995

Jun 12, 1992

7/897477

Rajiv Laroia - Silver Spring MD
Nariman Farvardin - Rockville MD
Steven A. Tretter - Silver Spring MD

University of Maryland - College Park MD

H04L 2534
H04L 512

375 17

A precoding scheme for noise whitening on ISI channels is presented where the scheme permits any type of shaping and is compatible with trellis coding. Its implementation complexity is significantly less than that of trellis precoding. The resulting reduction in shaping gain is small and becomes negligible as the rate per 2D of the constellation increases. This technique uses a structured vector quantization (SVQ) technique for optimal shaping of the constellation. Optimal (N-sphere) SVQ shaping results in higher shaping gains than those of Voronoi constellations based on known N-dimensional lattices. For a given CER. sub. 2 (or PAR. sub. 2) SVQ shaping results in optimal shaping. This is useful for implementation over QAM modems as significant shaping gains can be achieved even for a small constellation expansion. The SVQ-shaped constellations have a very reasonable implementation complexity. They allow for the possibility of opportunistic secondary channels, and there constituent 2D constellations are invariant to. pi.

4054838, Oct 18, 1977

Apr 19, 1976

5/678431

Steven Alan Tretter - Silver Spring MD

Rixon, Inc. - Silver Spring MD

H04L 512

325323

A system is provided for correcting phase jitter and frequency offsets in QAM modems. The system comprises (i) a narrow bandwidth, decision directed, phase-locked loop for tracking the average phase and frequency offsets followed by (ii) a phase jitter corrector located outside of the loop. The phase error signal for the jitter corrector is produced by passing the phase error signal of the phase-locked loop through a low pass filter designed to pass the expected jitter frequencies. Inphase and quadrature signals from the loop are delayed to compensate for the delay of the low pass filter, and the delayed signals, together with the filter output, are applied to a phase shifter which provides phase jitter correction using a rotational transformation.