公开(公告)号：AT122517T

公开(公告)日：1995-05-15

申请号：AT89901689

申请日：1988-12-16

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D

IPC: H04L27/36 ,  H03C3/40 ,  H03D7/16 ,  H04L27/12 ,  H04L27/20 ,  H04L27/34

公开(公告)号：CA1323402C

公开(公告)日：1993-10-19

申请号：CA610541

申请日：1989-09-07

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D

IPC: H04L27/01 ,  H04B3/10 ,  H04L27/06 ,  H04L27/22 ,  H04L27/38 ,  H03D1/02

Abstract: A method of demodulating a quadrature modulated signal includes first receiving the signal. The rf signal is then quadrature demodulated to produce in-phase and quadrature signals. One of these signals is filtered to produce a correction signal which is used for phase and amplitude correction. Both of the demodulated signals are again quadrature demodulated to produce the output signals. The second demodulation can be accomplished utilizing a correlation decoder. The applied correlation pulse includes a subcarrier component.

公开(公告)号：AT178172T

公开(公告)日：1999-04-15

申请号：AT92914890

申请日：1992-06-29

Applicant: MOTOROLA INC

Inventor： SIWIAK KAZIMIERZ ,  LEITCH CLIFFORD D ,  SCHWENDEMAN ROBERT J

IPC: H04B1/16 ,  H04B1/26 ,  H04B5/04 ,  H04W8/24 ,  H04W52/02 ,  H04W88/02 ,  H04B7/00 ,  H04Q7/14

公开(公告)号：CA2063403C

公开(公告)日：1994-05-03

申请号：CA2063403

申请日：1990-08-13

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D

IPC: H04B1/04 ,  H03G3/20 ,  H04L27/01 ,  H04L27/20

Abstract: 2063403 9103108 PCTABS00003 A gain/phase compensation method and apparatus for a linear amplifier feedback loop in a transmitter (100). The transmitter (100) includes an input (102 or 110), a linear amplifier (143), and a modulator (142), to provide a modulated carrier-frequency output signal. The transmitter also comprises a feedback detector (154), coupled to receive the output signal and also coupled to the input. The feedback detector (120) produces a detected baseband feedback signal and applies the feedback signal to the input. The transmitter (100) of the present invention further comprises stabilizing means (118 and 130), coupled to the input (102 or 110) and to the linear amplifier (143), for reducing the open-loop gain of the linear amplifier (143) to a value lower than one for all frequencies where the feedback loop causes the phase of the baseband input signal to shift by more than 180 degrees.

公开(公告)号：CA2139516A1

公开(公告)日：1994-01-06

申请号：CA2139516

申请日：1992-06-29

Applicant: MOTOROLA INC

Inventor： SIWIAK KAZIMIERZ ,  LEITCH CLIFFORD D ,  SCHWENDEMAN ROBERT J

IPC: H04B1/16 ,  H04B5/04 ,  H04W8/24 ,  H04W52/02 ,  H04W88/02

Abstract: A dual mode communication receiver a receiver for receiving information transmitted in a first and second modulation format on a common channel, a first demodulator for detecting information transmitted in the first modulation format, and a second demodulator, responsive to the information detected in the first modulation format, for detecting information transmitted in the second modulation format. A power conservation circuit is also provided for selectively supplying power to the first and second demodulators for enabling the detecting of the information transmitted in the first modulation format and the second modulation format, respectively.

公开(公告)号：SK118297A3

公开(公告)日：1998-05-06

申请号：SK118297

申请日：1996-01-11

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D ,  SCHWENDEMAN ROBERT J ,  MACNAK PHILIP P

IPC: H04B7/005 ,  H04L1/00 ,  H04L1/18 ,  H04W76/04 ,  H04W52/18 ,  H04W88/18 ,  H04B7/26 ,  H04K1/02

Abstract: A method and apparatus adaptively selects a communication strategy for communicating a message in a selective call radio communication system including a fixed portion (100) and a portable portion (101). The fixed portion (100) transmits (402) an alert signal to the portable portion (101), and awaits (404) an acknowledgment signal including a signal quality estimate from the portable portion (101). The portable portion (101) receives (602) the alert signal, and computes (604, 606) the signal quality estimate therefrom. The portable portion (101) then sends (608) the acknowledgment signal to the fixed portion (100). In response to the acknowledgment signal, the fixed portion (100) selects (407) a transmission strategy in accordance with the signal quality estimate. For compatibility, the transmission strategy requires a matching reception strategy in the portable portion (101). After sending the acknowledgment signal, the portable portion (101) selects (609) the matching reception strategy in accordance with the signal quality estimate sent in the acknowledgment signal without requiring further communication with the fixed portion (100).

公开(公告)号：AT126638T

公开(公告)日：1995-09-15

申请号：AT89906916

申请日：1989-05-22

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D ,  STEEL FRANCIS ROBERT

IPC: H04L27/14 ,  H04L27/18 ,  H04L27/22 ,  G11C11/26

公开(公告)号：CA1314080C

公开(公告)日：1993-03-02

申请号：CA583330

申请日：1988-11-17

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D

IPC: H04L27/36 ,  H03C3/40 ,  H03D7/16 ,  H04L27/12 ,  H04L27/20 ,  H04L27/34

Abstract: A quadrature amplitude modulation system utilizes two subcarrier signals, each quadrature modulated with information signals which are quadrature modulated onto the RF carrier. This provides a hole in the center of frequency spectrum, permitting carrier and bit sync signals can be provided in the center area of the signal spectrum.

公开(公告)号：FI920827A0

公开(公告)日：1992-02-25

申请号：FI920827

申请日：1992-02-25

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D

IPC: H03G3/20 ,  H04B1/04 ,  H04L27/01 ,  H04L27/20 ,  H04B

Abstract: A gain/phase compensation method and apparatus for a linear amplifier feedback loop in a transmitter (100). The transmitter (100) includes an input (102 or 110), alinear amplifier (143), and a modulator (142), to provide a modulator carrier-frequency output signal. The transmitter also comprises a feedback detector (154), coupled to receive the output signal and also coupled to the input. The feedback detector (120) produces a detected baseband feedback signal and applies the feedback signal to the input. The transmitter (100) of the present invention further comprises stabilizing means (118 and 130), coupled to the input (102 or 110) and to the linear amplifier (143), for reducing the open-loop gain of the linear amplifier (143) to a value lower than one for all frequencies where the feedback loop causes the phase of the baseband input signal to shift by more than 180 degrees.

公开(公告)号：CA1207391A

公开(公告)日：1986-07-08

申请号：CA424537

申请日：1983-03-25

Applicant: MOTOROLA INC

Inventor： LEITCH CLIFFORD D

IPC: H03F1/32 ,  H03F3/191 ,  H04B15/00

Abstract: A signal processing circuit is provided for amplifying low level modulated radio frequency signals up to relatively high levels in an efficient manner which minimizes the amount of undesired splatter components generated. The processing circuit alternately operates in a first linear mode for short periods of time and then in a highly efficient second mode for substantially longer periods of time thus achieving overall highly efficient signal amplification.