Jeffrey Chi Chu

US Patent:

6549755, Apr 15, 2003

Filed:

Apr 1, 2002

Appl. No.:

10/114373

Inventors:

Jeffrey C. Chu - Los Altos CA
Michael L. Downey - Fremont CA
Robert W. Estus - Woodside CA

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H04B 7185

US Classification:

455 134, 455 69, 455430, 455522, 375345

Abstract:

A method and apparatus for monitoring and controlling the operating point of a satellite transponder amplifier. In one aspect of the invention, a time domain signal received at a ground station is digitally sampled. Then, a histogram of the received signal is computed. To form the histogram, the digital samples are categorized according to which of a plurality of amplitude ranges each sample falls within. When plotted as a graph, the number of occurrences within each amplitude range forms the histogram. Under low compression levels, the histogram generally appears as an approximately bell-shaped curve. However, under higher compression levels, the bell-shaped curve becomes distorted. By correlating the acquired histogram to a template histogram, an amount of compression can be determined. This amount of compression indicates the operating point of the transponder amplifiers. If desired, the transmission power levels used by the satellite can be adjusted to ensure that the amplifiers operate at desired levels of compression.

US Patent:

7120392, Oct 10, 2006

Filed:

Oct 9, 2003

Appl. No.:

10/684147

Inventors:

Jeffrey C. Chu - Los Altos CA, US
Michael L. Downey - Fremont CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H04B 1/00
H04B 7/00

US Classification:

455 69, 455522, 455515, 455 6711

Abstract:

A method for providing power control to a uplink signal, comprising an uplink station transmitting an uplink signal to a satellite. The satellite also transmits a loopback signal representing the received uplink signal back to the uplink station. The satellite also transmits a beacon signal to the uplink station. The uplink station adjusts the power of the uplink signal based on measurements of the beacon signal and the uplink signal.

US Patent:

7466767, Dec 16, 2008

Filed:

Sep 13, 2004

Appl. No.:

10/940287

Inventors:

Jeffrey C. Chu - Los Altos CA, US
Michael L. Downey - Fremont CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H03D 1/24

US Classification:

375321

Abstract:

The invention is a signal processing system and method having increased bandwidth. An embodiment of the invention is a method of processing an analog input signal. The analog input signal is split into a first set of signals. The first set of signals are filtered. The first set of signals are digitized to form a second set of signals. The second set of signals are filtered to form a third set of signals. The third set of signals are combined to form a combined signal by adding the signals in the third set signals together to form a digital version of the analog input signal.

US Patent:

7639761, Dec 29, 2009

Filed:

Feb 26, 2003

Appl. No.:

10/375221

Inventors:

Jeffrey C. Chu - Los Altos CA, US
Michael L. Downey - Fremont CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H03D 1/04
H03H 7/30

US Classification:

375346, 375230

Abstract:

A method and system for measuring noise and or interference in a communications signal without taking the signal out of service. In the present invention the communications signal is converted from an RF signal into an IF signal. The IF signal is then digitized and stored. The stored signal is processed to determine the interference signal. The interference signal is calculated from an error vector produced by a blind equalizer demodulator. The interference signal is extracted and presented to a user.

US Patent:

7663547, Feb 16, 2010

Filed:

Apr 13, 2007

Appl. No.:

11/735158

Inventors:

Dominic K. C. Ho - Columbia MO, US
Jeffrey C. Chu - Los Altos CA, US
Michael L. Downey - Livermore CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

G01S 1/24
G01S 3/02

US Classification:

342387, 342442, 342453

Abstract:

Embodiments provide systems and methods for determining the geolocation of an emitter on earth based on weighted least-squares estimation based on two TDOA and two FDOA measurements, none of which need to be acquired at the same time. The four TDOA and FDOA measurements and the errors in each of the measurements are determined. Weights for the errors in the TDOA and FDOA measurements are determined, and the weights are applied in a weighted errors function. The weights account for the errors in the measurements and the errors in the satellite positions and velocities, and are dependent on the localization geometry. The weighted errors function is minimized to determine the location estimate of the unknown emitter.

US Patent:

7667640, Feb 23, 2010

Filed:

Apr 13, 2007

Appl. No.:

11/735146

Inventors:

Dominic K. C. Ho - Columbia MO, US
Jeffrey C. Chu - Los Altos CA, US
Michael L. Downey - Livermore CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H04B 7/185

US Classification:

34235701, 342387, 34235705

Abstract:

Embodiments provide systems and methods for determining the geolocation of an emitter on earth. A solution is obtained from two TDOA measurements that need not be acquired at the same time. A solution is obtained from a TDOA measurement and an FDOA measurement that need not be acquired at the same time and need not be coming from the same satellite pair. A location of an emitter can be determined from minimizing a cost function of the weighted combination of the six solutions derived from the two TDOA measurements and the two FDOA measurements, where the weight of each solution in the combination is determined based on the intersection angle of the two curves that define the possible locations of the emitter based on the TDOA and/or FDOA measurements.

US Patent:

8004459, Aug 23, 2011

Filed:

Nov 13, 2009

Appl. No.:

12/618684

Inventors:

Dominic K. C. Ho - Columbia MO, US
Jeffrey C. Chu - Los Altos CA, US
Michael L. Downey - Livermore CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H04B 7/185
G01S 1/24
G01S 1/22

US Classification:

342353, 342387, 342393

Abstract:

Embodiments provide systems and methods for determining the geolocation of an emitter on earth. A solution is obtained from two TDOA measurements that need not be acquired at the same time. A solution is obtained from a TDOA measurement and an FDOA measurement that need not be acquired at the same time and need not be coming from the same satellite pair. A location of an emitter can be determined from minimizing a cost function of the weighted combination of the six solutions derived from the two TDOA measurements and the two FDOA measurements, where the weight of each solution in the combination is determined based on the intersection angle of the two curves that define the possible locations of the emitter based on the TDOA and/or FDOA measurements.

US Patent:

8433015, Apr 30, 2013

Filed:

Apr 2, 2010

Appl. No.:

12/753644

Inventors:

Michael L. Downey - Livermore CA, US
Jeffrey C. Chu - Los Altos CA, US

Assignee:

Glowlink Communications Technology, Inc. - Los Altos CA

International Classification:

H03D 1/04

US Classification:

375346, 375285

Abstract:

A system for and method of removing one or more unwanted inband signals from a received communications signal is described. The inband signal or signals may comprise noise, interference signals, or any other unwanted signals that impact the quality of the underlying communications. A receiver receives a communication signal, the received communication signal including the desired communication signal and one or more inband signals. A signal processor processes the received signal to form an estimate of the desired communication signal and an estimate of the inband signals. The estimate of the inband signals is thereby removed from the received signal. The estimate of the desired communication signal and the estimate of the inband signals are formed without prior knowledge of characteristics of the inband signals and without obtaining a copy of any of the inband signals from any source other than the received signal.