Frank David Liu, 4174 Claypit Hill Rd, Wayland, MA 01778

7254186, Aug 7, 2007

Jul 22, 2003

10/624312

Frank Liu - Princeton NJ, US

M/A-Com, Inc. - Lowell MA

H03K 9/00

375316

The invention is directed to a system for processing an electromagnetic wave by receiving rectangular coordinate information for the electromagnetic wave; and directly converting the rectangular coordinate information into a magnitude signal, a sin(Φ), and a cos(Φ) signal using a CORDIC algorithm, where Φ represents a phase of the electromagnetic wave. The direct converting my be accomplished using shift and add/subtract operations in a processor and a look-up table, or by using at least two cascaded processors employing the CORDIC algorithm.

7340007, Mar 4, 2008

Sep 16, 2003

10/663136

Frank Liu - Princeton NJ, US

M/A-COM, Inc. - Lowell MA

H04L 27/00

375297

The invention is directed to a system for determining a transfer function for emphasizing an electromagnetic signal prior to being processed by determining a discrete transfer function for a processing system, such as a wideband phase modulator; determining a target transfer function such that the target transfer function multiplied by the inverse of the discrete transfer function produces a discrete pre-emphasis transfer function; and transforming any unstable poles and/or zeros in the pre-emphasis transfer function to stable poles and/or zeros. The discrete transfer function may be determined, for example, by using an S-function, input and output signals, the inverse-invariant method, and/or the Steiglitz-McBride algorithm. The transformation of the unstable poles and/or zeros may be accomplished using an all pass filter. The target transfer function may be a low pass FIR filter having a gain of about unity across substantially all of the frequency range of said FIR filter.

7356091, Apr 8, 2008

Dec 9, 2003

10/731354

Frank Liu - Princeton NJ, US

M/A-COM, Inc. - Lowell MA

H04L 27/04

375295, 455 91

The invention relates to a system for processing an electromagnetic input signal in which processing circuitry may be used to produce a bounded phase signal, such as by calculating an n-bit 2's compliment number in the range of [−1, 1] from phase sample information for an input wave; and producing an unwrapped phase difference signal from the bound phase signal, such as by taking a 2's compliment subtraction using another wrapped phase signal from previous phase sample information. A corrected phase signal may also be used by taking a 2's complement addition using the bounded phase signal, wherein the unwrapped phase difference signal is produced using the corrected phase signal.

4321624, Mar 23, 1982

Oct 30, 1978

5/955516

Walter G. Gibson - Princeton NJ
Frank C. Liu - Piscataway NJ

RCA Corporation - New York NY

H04N 550

3581951

An automatic fine tuning (AFT) circuit is provided which generates an AFT control signal in response to a video intermedate frequency (I. F. ) signal. The I. F. signal is supplied to the input of a current source amplifier, which provides current signals of like phase relationship to a discriminator network. The discriminator network is comprised of two tuned circuits, one of which is resonant at a frequency below the desired frequency of the I. F. picture carrier, and the other resonant at a frequency above the desired frequency. The tuned circuits develop voltage variations which vary differentially in magnitude in response to the frequency deviation of the I. F. picture carrier from its desired frequency. The differentially related voltages are detected by two peak detector networks for use as AFT control signals. The current source amplifier and peak detector networks may be conveniently fabricated on a single I. C. chip.

4263611, Apr 21, 1981

Aug 29, 1979

6/070903

Walter G. Gibson - Princeton NJ
Frank C. Liu - Kendall Park NJ
Max W. Muterspaugh - Indianapolis IN

RCA Corporation - New York NY

H04N 950
H04N 550

358 23

A selectivity network is provided for a synchronous detector, a reference signal circuit, and an AFT circuit. The selectivity network comprises a first tuned circuit coupled across two terminals of the reference signal circuit and tuned to the desired frequency of the I. F. picture carrier. A second tuned circuit is lightly coupled to the first tuned circuit and is coupled across two inputs of the AFT circuit to provide a frequency dependent phase-sifted reference signal to the AFT circuit. The first tuned circuit includes a trap circuit tuned to provide attenuation about a frequency intermediate the frequency of a sound carrier and that picture signal sideband frequency which, upon detection, results in a video signal corresponding to the intercarrier sound second subharmonic frequency. The trap in the reference signal tuned circuit minimizes quadrature distortion in the reference channel and the resultant harmonic distortion in the video signals, which causes sound buzz. The frequency notched reference signal is applied to the AFT tuned circuit, which causes a balancing of the pull-in range of the AFT circuit about the desired picture carrier frequency, thereby immunizing the AFT circuit against noise-pulling.