Long T Huynh

6680987, Jan 20, 2004

Aug 8, 2000

09/634018

Bassel F. Beidas - Alexandria VA
Long Huynh - San Diego CA

Hughes Electronics Corporation - El Segundo CA

H04D 100

375343, 375142, 375143

A method for estimating and compensating for a fading communications channel includes the steps of generating matched filter data from a received data burst, interpolating between reference symbols to generate a fading channel estimate from the matched filter data, applying a phase correction to the matched filter data from the fading channel estimate to recover free data from the matched filter data, and performing decision feedback on the free data to improve the fading channel estimate.

7016444, Mar 21, 2006

Mar 26, 2002

10/106940

Michael Parr - Del Mar CA, US
Sharath Ananth - San Diego CA, US
Long Huynh - San Diego CA, US
Drew Barnett - La Jolla CA, US
Fred Harris - Lemon Grove CA, US

Hughes Network Systems, LLC - Germantown MD

H04L 7/00

375354

Filtering loop and method for maintaining synchronization between a receiver and a transmitter reduces overhead and enables more robust operation. The method includes the step of receiving an error signal corresponding to a synchronization parameter. A first order filter is applied to the error signal such that a residual signal results. The method further provides for compensating the residual signal for drift such that the compensated residual signal estimates a rate of change in the residual signal. By compensating the residual signal for drift, difficulties associated with time lag and signal degradation are obviated.

20030002471, Jan 2, 2003

Nov 26, 2001

09/994519

James Crawford - San Diego CA, US
Long Huynh - San Diego CA, US

H04J001/00

370/343000, 370/480000

A scheme for estimating the carrier-to-noise-plus-interference ratio (CNIR) for Orthogonal Frequency-Division Multiplexing (OFDM) waveforms makes use of a physical waveform frame structure including a diversity selection portion. The diversity selection portion may be located at the end of a burst as a postamble and includes one or more OFDM symbols each having a frequency bin structure including both non-zero and zero OFDM frequency bin content. A first set of measurements are taken from an antenna branch on the non-zero OFDM frequency bins, and a second set of measurements are taken from the antenna branch on the zero OFDM frequency bins. An estimate for CNIR for at least one of the non-zero OFDM frequency bins and at least one of the zero OFDM frequency bins of the antenna branch is then computed using the first and second set of measurements.

55132219, Apr 30, 1996

Aug 25, 1994

8/279965

Michael Parr - San Diego CA
Long Huynh - San Diego CA

Hughes Aircraft Company - Los Angeles CA

H03H 730
H03H 740
H03K 5159
H04L 2706

375344

A device and method of adjusting an equalizer in a digital communications receiver in response to relative velocity between the communications receiver and a communications transmitter. A radio frequency receiver receives a radio frequency signal from the communications transmitter through a communications channel, and an analog to digital converter digitizes a first portion of the radio frequency signal during a first time period, and generates a first data signal made up of digital samples. The analog to digital converter also digitizes a second portion of the radio frequency signal during a second time period and generates a second data signal, also made up of samples. A channel estimator estimates characteristics of the communications channel in response to a portion of the first data signal, and generates a first channel estimate in response thereto. Finally, a processor determines an estimated velocity of the communications receiver relative to the communications transmitter, weights the first channel estimate in response to the estimated velocity, and generates a revised channel estimate in response to the weighting of the first channel estimate and the second data signal.

55749895, Nov 12, 1996

Oct 13, 1994

8/322963

John Watson - Carlsbad CA
Youngky Kim - Potomac MD
Long Huynh - San Diego CA
Michael Parr - San Diego CA

Hughes Electronics - Los Angeles CA

H04B 706

455101

A cellular base station (10) in a digital cellular system employs transmitting circuitry in which voice signals (15) are processed at a low frequency level (12) into two separate paths. A first of the low frequency signals is variably delayed (20), and the first and the other low frequency signals are upconverted to radio frequency level (16,22) for transmission over independent time-spaced transmission paths (26,28) to cellular receivers. A receiver downconverts and demodulates the radio frequency diversity signals, and then combines the demodulated diversity signals to generate an equalized combination diversity signal for receiver output processing.

57063141, Jan 6, 1998

May 11, 1995

8/439329

Mark Davis - Carlsbad CA
Long Huynh - San Diego CA

Hughes Electronics - Los Angeles CA

H04L 2706

375340

A system and method for jointly determining initial tap coefficients for a maximum likelihood sequence estimating equalizer and a timing error of an incoming signal, in one embodiment, receives the incoming signal into a receiver, and locates a known portion within a time frame of the incoming signal. The known portion is compared with a stored representation of the known portion, and with a stored representation of a derivative of the known portion. The initial tap coefficients and timing error of the incoming signal are jointly determined based on the comparing of the known portion with the stored representations, and a subsequent known portion is located within a subsequent time frame of the incoming signal based on the timing error. The initial tap coefficients are passed to a maximum likelihood sequence estimating equalizer.

56595760, Aug 19, 1997

Jul 25, 1994

8/279724

David N. Critchlow - San Diego CA
Michael Parr - San Diego CA
Long Huynh - San Diego CA

Hughes Electronics - Los Angeles CA

H04B 138
H04L 516

375219

A device and method for receiving a radio signal transmitted over a channel, selecting and deselecting an equalizer, and balancing processing in response to such selection. A radio frequency signal is received from a transmission channel into a receive path, and delay spread in the radio frequency signal is estimated using an analysis circuit. The analysis circuit also determines a threshold delay spread. In the event the estimated delay spread exceeds the threshold delay spread, an equalizer is selected, otherwise the equalizer is deselected. Similarly, in the event the estimated delay spread does not exceed the threshold delay spread, a high complexity processor is selected, otherwise a low complexity processor is selected. If the low complexity processor is selected, an output signal is generated using the low complexity processor, and if the high complexity processor is selected, the output signal is generated using the high complexity processor.

60289015, Feb 22, 2000

May 19, 1994

8/246851

Long Huynh - San Diego CA
Michael Parr - San Diego CA

Hughes Electronics Corporation - El Segundo CA

H04B 110
H03H 730

375350

A device and method of selecting and deselecting an equalizer in a digital communications receiver. The method includes receiving a receiver signal, estimating an estimated delay spread in the receiver signal, and determining a threshold delay spread. In the event the estimated delay spread exceeds the threshold delay spread, the method includes selecting the equalizer. In the event the estimated delay spread does not exceed the threshold delay spread, the method includes deselecting the equalizer. The method also includes generating a receiver output signal in response to an equalizer signal in the event the equalizer is selected, and generating the receiver output signal in response to the receiver signal in the event the delay spread does not exceed the threshold. The device includes a radio receiver that receives the receiver signal and an analysis circuit coupled to the radio receiver. The analysis circuit estimates the estimated delay spread in the radio signal, and determines the threshold delay spread.