Kikuo S Ichiroku

52669521, Nov 30, 1993

Mar 30, 1992

7/860528

Wade J. Stone - Topanga CA
Howard S. Nussbaum - Los Angeles CA
Kikuo Ichiroku - Santa Monica CA
Benjamin Felder - Saugus CA
William P. Posey - Playa Del Rey CA

Hughes Aircraft Company - Los Angeles CA

H03M 112
H03M 304

341156

A linear predictive ADC employs a fully feed forward design to extend its dynamic range, allow greater speed of operation, achieve stable operation and eliminate a requirement for sample-and-hold circuits. A first quantizer (Qc) converts an input analog signal to a digital format, while a signal predictor (32) predicts a subsequent value of the input signal. After conversion back to analog format, the predicted signal is compared with the actual subsequent value of the input signal to produce an error signal that is converted to a digital format by a second quantizer (Qf). The digital predicted signal is fed forward and combined with the digital error signal to produce a high precision digital output. The analog error signal is preferably amplified prior to digitation to take advantage of the full bit capacity of the second quanitzer (Qf), and then digitally de-amplified back to its original scale. Digital gain and offset adjustment mechanisms (44, 50) are preferably provided to compensate for amplification/de-amplification mismatches and system offsets.

52512185, Oct 5, 1993

Jul 31, 1991

7/739593

Wade J. Stone - Topanga CA
Kikuo Ichiroku - Santa Monica CA
Edwin A. Kelley - Los Angeles CA
Don C. Devendorf - Carlsbad CA

Hughes Aircraft Company - Los Angeles CA

H04J 100

370120

A digital radio frequency (RF) or intermediate frequency (IF) receiver for frequency division multiplexed (FDM) signals contained in a predetermined FDM band including an RF amplifier, an RF bandpass anti-alias filter, and an analog-to-digital (A/D) converter. The sample frequency F. sub. s of the A/D converter is lower than the lowest frequency in the predetermined FDM band and is selected to meet certain specified conditions based on the passband and stop band edges of the anti-alias filter so that the output of the A/D converter contains a non-distorted aliased frequency down converted digital version of the predetermined FDM band which is located between 0 Hz and one-half the sampling frequency. A digital complex mixer responsive to the digital output of the A/D converter translates the spectrum of the sampled digital received signal to center the desired FDM channel at zero frequency (DC). Digital low pass filtering isolates the desired channel centered at DC, and a digital complex mixer can be used to translate the isolated selected channel to a predetermined IF frequency.

50581074, Oct 15, 1991

Jan 5, 1989

7/293894

Wade J. Stone - Los Angeles CA
Kikuo Ichiroku - Santa Monica CA
Edwin A. Kelley - Los Angeles CA
Don C. Devendorf - Los Angeles CA

Hughes Aircraft Company - Los Angeles CA

H04J 100

370 691

A digital intermediate frequency (IF) receiver for frequency division multiplexed (FDM) signals including analog circuitry for receiving FDM signals and an analog-to-digital (A/D) converter for converting the received signals to a sampled digital received signal. A digital complex mixer responsive to the digital output of the A/D converter translates the spectrum of the sampled digital received signal to center the desired FDM channel at zero frequency (DC). Digital low pass filtering isolates the desired channel centered at DC, and a digital complex mixer can be used to translate the isolated selected channel to a predetermined IF frequency. The in-phase portion of the digital IF centered selected channel or the DC centered complex envelope selected channel can then be provided to appropriate demodulation or decoder networks.