Michael Shane Spencer

US Patent:

7109789, Sep 19, 2006

Filed:

Jan 21, 2003

Appl. No.:

10/501896

Inventors:

Michael E. Spencer - Escondido CA, US

Assignee:

American Technology Corporation - San Diego CA

International Classification:

H03F 3/38

US Classification:

330 10, 330251

Abstract:

A modulator-amplifier configured for use in parametric sound reproduction systems, including an input configured for receiving at least one input signal, a reference signal generator configured for generating a reference signal, and a comparator stage coupled to the input and the reference signal generator, the comparator stage configured for detecting relationships between a first signal based on the input signal and the reference signal. A switching power stage coupled to the comparator is configured to receive a second signal derived from a combination of an output from the comparators and the input signal, wherein there is a non-linear relationship between the input signal and the timing of state transitions in the switching power stage for the purpose of generating an output that has been shifted in frequency relative to a frequency of the input signal, and which includes at least one sideband.

US Patent:

7162042, Jan 9, 2007

Filed:

Mar 21, 2003

Appl. No.:

10/393893

Inventors:

Michael E. Spencer - Escondido CA, US
Joseph O. Norris - Honolulu HI, US

Assignee:

American Technology Corporation - San Diego CA

International Classification:

H04B 3/00

US Classification:

381 77, 381 79

Abstract:

A parametric loudspeaker system using improved modulators to compensate for the non-linearity of the parametric process in air when driving the air at saturation levels and below saturation levels. The parametric loudspeaker uses a pre-processed single sideband modulator that offers ideal linearity as characterized by square root pre-processed double sideband modulators but with a lower carrier frequency and without the wide bandwidth requirements. By eliminating some or all of the lower sideband the carrier frequency can be reduced without producing sideband frequencies in the audible range. Lower operational frequencies result in greater translation efficiency and greater output capability before reaching the saturation limit of air. A pre-processor minimizes the effects of saturation limits for double sideband, truncated double sideband or single sideband processing to achieve superior output.

US Patent:

7224219, May 29, 2007

Filed:

Sep 18, 2006

Appl. No.:

11/523363

Inventors:

Michael E Spencer - Escondido CA, US

Assignee:

American Technology Corporation - San Diego CA

International Classification:

H03F 3/38

US Classification:

330 10, 330251

Abstract:

A method and device for frequency shifting and amplifying an audio signal for use in a parametric loudspeaker system is disclosed. The method includes the operation of receiving an input audio signal and creating a reference signal. The audio signal is compared with the reference signal to derive a compared product signal. The compared product signal is sent to a switching power stage. Nonlinear preprocessing is performed with respect to the input audio signal, and/or a non-triangle wave is created as the reference signal. The input audio signal is shifted and amplified by modulating the reference signal in the switching power stage.

US Patent:

7729498, Jun 1, 2010

Filed:

Jan 9, 2007

Appl. No.:

11/651944

Inventors:

Michael E. Spencer - Escondido CA, US
Joseph O. Norris - Kapolei HI, US

Assignee:

American Technology Corporation - San Diego CA

International Classification:

H04B 3/00

US Classification:

381 77

Abstract:

A parametric loudspeaker system using improved modulators to compensate for the non-linearity of the parametric process in air when driving the air at saturation levels and below saturation levels. The parametric loudspeaker uses a pre-processed single sideband modulator that offers ideal linearity as characterized by square root pre-processed double sideband modulators but with a lower carrier frequency and without the wide bandwidth requirements. By eliminating some or all of the lower sideband the carrier frequency can be reduced without producing sideband frequencies in the audible range. Lower operational frequencies result in greater translation efficiency and greater output capability before reaching the saturation limit of air. A pre-processor minimizes the effects of saturation limits for double sideband, truncated double sideband or single sideband processing to achieve superior output.

US Patent:

20030091203, May 15, 2003

Filed:

Aug 30, 2002

Appl. No.:

10/232755

Inventors:

James Croft - Poway CA, US
Michael Spencer - Redondo Beach CA, US

Assignee:

American Technology Corporation

International Classification:

H04R003/00

US Classification:

381/111000

Abstract:

A system configured to dynamically adjust the ultrasonic carrier level in a parametric array system in response to changing source signal input levels, and which employs a look-ahead delay strategy to enable optimal modulation of the carrier wave to eliminate constant ultrasonic carrier emission and reduce the ultrasonic carrier emission to what is actually needed to accommodate the db range of the source material, and at the same time, to also minimize noticeable distortion and sound artifacts of a high-power ultrasonic carrier, and/or distortion/artifacts arising from modulation of an ultrasonic carrier to reduce average power output; and thus it realizes advantages of carrier modulation based on source-signal level, while minimizing inherent drawbacks of carrier modulation.