David L Roberson

US Patent:

53655508, Nov 15, 1994

Filed:

Jul 18, 1991

Appl. No.:

7/732461

Inventors:

David L. Roberson - Forest VA

Assignee:

Pulse Electronics, Inc. - Rockville MD

International Classification:

H04L 2730

US Classification:

375 1

Abstract:

A direct sequence digital spread spectrum receiver acquires and maintains synchronization in a reliable, yet simple manner, even under severe multipath and interference conditions. A sliding correlator and a voltage controlled crystal oscillator (VCXO) cooperate to acquire initial synchronization, and once synchronization is acquired, the VCXO is linearly frequency modulated (FM) for accurate tracking. The difficult problem of keeping the receiver code clock synchronized to that of the transmitter under severe multipath and interference conditions is solved by virtue of a dual switched bandwidth low pass filter section of the tracking circuit, allowing a wide bandwidth for initial acquisition and tracking but once the clocks are aligned, a narrow loop takes over that follows the transmitter closely. A commercially available intermediate frequency (IF) integrated circuit (IC) is used as an amplitude modulated (AM) detector to achieve the large dynamic range required. The IF IC has an internal received signal strength indicator (RSSI) output which is used to demodulate the amplitude variations generated by the tracking circuit.

US Patent:

43429696, Aug 3, 1982

Filed:

Oct 6, 1980

Appl. No.:

6/194681

Inventors:

Richard T. Myers - Lynchburg VA
David L. Roberson - Lynchburg VA

Assignee:

General Electric Company - Lynchburg VA

International Classification:

H01P 502
H01P 700

US Classification:

333 33

Abstract:

Impedance matching between a helical resonator of a helical resonator filter and a circuit connected thereto is accomplished by the provision of a microstrip transmission line including a microstrip stub printed on a printed circuit board, the microstrip stub being short in comparison to the wavelength at the resonant frequency of the filter whereby the microstrip stub assumes the characteristics of an inductive impedance. A first electrical end of the microstrip stub is connected to a first terminal of the helical resonator and to a first terminal of the circuit, and a second electrical end of the microstrip stub is connected to a second terminal of the helical resonator and to a second terminal of the circuit.

US Patent:

63071517, Oct 23, 2001

Filed:

Jun 2, 1999

Appl. No.:

9/324111

Inventors:

David L. Roberson - Forest VA

Assignee:

Ericsson, Inc. - Research Triangle Park NC

International Classification:

H05K 900

US Classification:

174 35R

Abstract:

A technique for reducing low frequency baseband interference noise is disclosed. The low frequency baseband interference noise typically takes the form of low frequency magnetic interference emanating from a power source providing low frequency switching currents. The power source typically has a supply current terminal and an oppositely disposed return current terminal. The technique is realized by enclosing the power source in an electrically conductive sheath, wherein the electrically conductive sheath has an input terminal disposed proximate the supply current terminal and an output terminal disposed proximate the return current terminal. The output terminal is electrically connected to the return current terminal. Also, the electrically conductive sheath has an opening proximate the supply current terminal for allowing access to the supply current terminal.

US Patent:

55128785, Apr 30, 1996

Filed:

Oct 6, 1994

Appl. No.:

8/319263

Inventors:

Brent Balch - Fort Lauderdale FL
David L. Roberson - Forest VA

Assignee:

Sensormatic Electronics Corporation - Deerfield FL

International Classification:

G08B 1314

US Classification:

340572

Abstract:

An electronic article surveillance (EAS) system includes a transmitting antenna, a driver operable for exciting the transmitting antenna, a receiving antenna and circuitry connected to the receiving antenna for improving the quality of transmissions from the transmitting antenna. The driver excites the transmitting antenna at a preselected system operating frequency and the circuitry connected to the receiving antenna improves the quality of transmissions from the transmitting antenna by lessening harmonics of the operating frequency in the transmissions. The harmonics are attributable to protection diodes connected to the receiving antenna for limiting voltages impressed thereon and otherwise adversely impacting on the receiver tag signal processing circuitry. The harmonic lessening circuitry is connected in parallel with the protection diodes and is operative to lessen protection diode harmonic generation.

US Patent:

52396967, Aug 24, 1993

Filed:

Oct 15, 1991

Appl. No.:

7/778461

Inventors:

Brent F. Balch - Fort Lauderdale FL
David Roberson - Forest VA

Assignee:

Sensormatic Electronics Corporation - Deerfield Beach FL

International Classification:

H04B 104

US Classification:

455127

Abstract:

A transmitter for an electronic article surveillance system having a power amplifier for forming a drive signal for causing a current to flow through an antenna. The magnitude of the current flowing through the antenna is sensed and, based upon the sensed current, the drive signal is continuously controlled.

US Patent:

51893975, Feb 23, 1993

Filed:

Jan 9, 1992

Appl. No.:

7/820313

Inventors:

Harry E. Watkins - Boca Raton FL
David L. Roberson - Forest VA

Assignee:

Sensormatic Electronics Corporation - Deerfield Beach FL

International Classification:

G08B 1324

US Classification:

340572

Abstract:

A method and apparatus for determining the amplitude of a first magnetic field at a first fundamental frequency in a zone in which a second magnetic field is able to be present wherein first and second transmissions of a magnetic field at the fundamental frequency and different phases is carried out at different times, the field in the zone is detected for each transmission and the detected fields are processed to determine the magnitude of the first magnetic field.