Mark C Sullivan

US Patent:

6560536, May 6, 2003

Filed:

Apr 11, 2001

Appl. No.:

09/829993

Inventors:

Mark C. Sullivan - Annandale VA
James B. Kilfeather - Purcellville VA

Assignee:

Eagle-Eye, Inc. - Dulles VA

International Classification:

H04B 7185

US Classification:

701214, 701213, 342357, 34235701, 34235703, 34235706, 34235709, 34235712, 455 121, 455422, 455440, 375 96

Abstract:

A geographic tracking system with minimal power and size required at the mobile terminal collects observation data at the mobile terminal, forwards the data to a processor, which calculates the position. The mobile terminal needs only to gather a few milliseconds of observation data, and to relay this observation data to the processor. The range from the satellite (or other airborne transponder) to the terminal is determined using the known positions of an interrogating transmitter and a satellite, and a known terminal delay between the received signal and the transmission of the return signal, and the round trip time. An arc of locations is determined by computing an intersection of a sphere centered at the satellite having a radius given by the calculated range with a model of the Earths surface. Alternatively, candidate locations that are consistent with the carrier signal received from GPS satellites can be used. In either case, the candidate points are considered and refined using code phase measurements from a set of GPS satellites.

US Patent:

6725158, Apr 20, 2004

Filed:

Jul 10, 2002

Appl. No.:

10/191288

Inventors:

Mark C. Sullivan - Annandale VA
James B. Kilfeather - Purcellville VA

Assignee:

SkyBitz, Inc. - Dulles VA

International Classification:

G01S 502

US Classification:

701213, 34235701, 34235706, 34235709, 455 121, 455427

Abstract:

A geographic tracking system with minimal power and size required at the mobile terminal collects observation data at the mobile terminal, forwards the data to a processor, which calculates the position. The mobile terminal needs only to gather a few milliseconds of observation data, and to relay this observation data to the processor. The range from the satellite (or other airborne transponder) to the terminal is determined using the known positions of an interrogating transmitter and a satellite, and a known terminal delay between the received signal and the transmission of the return signal, and the round trip time. An arc of locations is determined by computing an intersection of a sphere centered at the satellite having a radius given by the calculated range with a model of the Earths surface. The candidate points are considered and refined using code phase measurements from a set of GPS satellites. The candidate point having the lowest residuals or expected to measured code phases is chosen as the location of the mobile terminal.

US Patent:

7010066, Mar 7, 2006

Filed:

Aug 9, 2001

Appl. No.:

09/924542

Inventors:

Mark C. Sullivan - Annandale VA, US

Assignee:

SkyBitz, Inc. - Sterling VA

International Classification:

H03D 1/00

US Classification:

375343

Abstract:

A GPS receiver acquires carrier frequency and Gold code phase using short segments of a received GPS signal. In one embodiment, a 1-ms segment of the GPS signal is transformed to the frequency domain. This is multiplied by a frequency representation of the Gold code. The resulting product is converted to the time domain, and a peak is detected. The location of the peak corresponds to the code phase. If no peak is located, the carrier frequency is changed. Full- and half-bin steps in carrier frequency are considered. Processing gain is achieved by using longer segments of the input signal, for example 4 or 16 ms and integrating 1-ms segments. Considerations are provided for compensating for the effects of a transition, should it occur in the short segment of the GPS signal being processed. Integrations can be performed using non-coherent and coherent techniques.

US Patent:

7020190, Mar 28, 2006

Filed:

Aug 9, 2001

Appl. No.:

09/925011

Inventors:

Mark C. Sullivan - Annandale VA, US

Assignee:

SkyBitz, Inc. - Sterling VA

International Classification:

H04B 1/38

US Classification:

375222, 708160, 708622

Abstract:

A frequency translator uses a CORDIC phase rotator coupled to a phase accumulator to translate an input signal in frequency. The CORDIC phase rotator performs required phase angle rotations of input vectors using only shift and add operations. Thus, the frequency translator can be readily implemented in hardware. Higher precision arithmetic is used in the CORDIC phase rotator operations than the input vectors contain. To avoid truncation error at the output of the CORDIC phase rotator, stochastic rounding is employed. A dither signal is added to avoid errors due to nonlinear operation of D/A converters, where D/A conversion of the frequency translated signal is required.

US Patent:

7027486, Apr 11, 2006

Filed:

Sep 10, 2001

Appl. No.:

09/948629

Inventors:

Mark C. Sullivan - Annandale VA, US

Assignee:

SkyBitz, Inc. - Sterling VA

International Classification:

H04B 1/707

US Classification:

375147

Abstract:

A GPS receiver acquires carrier frequency and Gold code phase using short segments of a received GPS signal. In one embodiment, a 1-ms segment of the GPS signal is transformed to the frequency domain. This is multiplied by a frequency representation of the Gold code. The resulting product is converted to the time domain, and a peak is detected. The location of the peak corresponds to the code phase. If no peak is located, the carrier frequency is changed. Full- and half-bin steps in carrier frequency are considered. Processing gain is achieved by using longer segments of the input signal, for example 4 or 16 ms and integrating 1-ms segments. Considerations are provided for compensating for the effects of a transition, should it occur in the short segment of the GPS signal being processed. Integrations can be performed using non-coherent and coherent techniques. Adjustments are made for non-integral millisecond segment lengths.

US Patent:

7266142, Sep 4, 2007

Filed:

Feb 2, 2006

Appl. No.:

11/345670

Inventors:

Mark C. Sullivan - Annandale VA, US

Assignee:

SkyBitz, Inc. - Sterling VA

International Classification:

H04B 1/707

US Classification:

375147, 375316

Abstract:

A GPS receiver acquires carrier frequency and Gold code phase using short segments of a received GPS signal. In one embodiment, a 1-ms segment of the GPS signal is transformed to the frequency domain. This is multiplied by a frequency representation of the Gold code. The resulting product is converted to the time domain, and a peak is detected. The location of the peak corresponds to the code phase. If no peak is located, the carrier frequency is changed. Full- and half-bin steps in carrier frequency are considered. Processing gain is achieved by using longer segments of the input signal, for example 4 or 16 ms and integrating 1-ms segments. Considerations are provided for compensating for the effects of a transition, should it occur in the short segment of the GPS signal being processed. Integrations can be performed using non-coherent and coherent techniques. Adjustments are made for non-integral millisecond segment lengths.

US Patent:

7327783, Feb 5, 2008

Filed:

Feb 2, 2006

Appl. No.:

11/345671

Inventors:

Mark C. Sullivan - Annandale VA, US

Assignee:

SkyBitz, Inc. - Sterling VA

International Classification:

H04B 1/38

US Classification:

375222, 708160, 708622

Abstract:

A frequency translator uses a CORDIC phase rotator coupled to a phase accumulator to translate an input signal in frequency. The CORDIC phase rotator performs required phase angle rotations of input vectors using only shift and add operations. Thus, the frequency translator can be readily implemented in hardware. Higher precision arithmetic is used in the CORDIC phase rotator operations than the input vectors contain. To avoid truncation error at the output of the CORDIC phase rotator, stochastic rounding is employed. A dither signal is added to avoid errors due to nonlinear operation of D/A converters, where D/A conversion of the frequency translated signal is required.

US Patent:

7365527, Apr 29, 2008

Filed:

Apr 22, 2003

Appl. No.:

10/419880

Inventors:

Mark Sullivan - Annandale VA, US
Darryl S. Bierly - Aldie VA, US

Assignee:

Argon Engineering - Fairfax VA

International Classification:

G01R 23/00
G01R 23/16
G01R 13/14
G01R 23/165

US Classification:

324 7619, 324 7621, 324 7624, 324 7631

Abstract:

A range of a frequency measuring device having limited range is extended by pre-processing an input signal. The input signal is divided into a plurality of channels. In each channel, the input signal is divided into sub-bands. A frequency of the input signal is determined using a frequency measuring device having limited range. The frequencies are stored in a frequency set. The frequency set is used to determine a frequency associated with the input signal according a set of pre-determined reconstruction rules.