David R Ford

US Patent:

51704927, Dec 8, 1992

Filed:

Dec 13, 1991

Appl. No.:

7/808941

Inventors:

Paul J. Moller - Streamwood IL
Douglas W. Main - Palatine IL
David K. Ford - Mesa AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 140
H04B 700

US Classification:

455 76

Abstract:

A unique cellular telephone (100) digitally frequency locks to the received base station transmitter signal. The cellular telephone (100) includes a radio transceiver (106), a reference oscillator (104), and microcomputer (102) with memory therein for controlling the operation thereof. The radio transceiver (106) includes a phase-locked loop (PLL) synthesizer 120, a receiver mixer (122) followed by one or more gain stages (124), a phase detector (126), and a divider (128). The PLL synthesizer (120) generates a signal locked to the reference oscillator (104) that is mixed with the incoming base station transmitter signal in the receive mixer (122) to generate an intermediate frequency signal. The output of the reference oscillator (104) also feeds the divider (128), which divides the reference oscillator signal by an amount so as to generate the divided signal having a frequency substantially the same as the frequency of the intermediate frequency signal from the mixer (122). The output of the divider (128) and the amplified intermediate frequency signal from the amplifier (124) are both fed into the phase detector (126), which generates a binary error signal (110).

US Patent:

50602640, Oct 22, 1991

Filed:

Jan 5, 1990

Appl. No.:

7/461570

Inventors:

Grazyna E. Muellner - Bartlett IL
Rafaele Pini - Norridge IL
Dennis Cashen - Lake Zurich IL
Patrick J. Marry - Cary IL
David K. Ford - Mesa AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04L 900

US Classification:

380 46

Abstract:

A controller for a radiotelephone having the capability of operation in both a secure mode for call authorization and a nonsecure mode for user interface is disclosed. The nonsecure mode and secure mode of operation are both resident in a single microcontroller which runs the nonsecure operations until a requirement for the secure operation is requested during call placement. The nonsecure mode is disabled during the period of time the secure mode is operational and is reenabled upon completion of the secure mode operation. The secure mode cannot be accessed externally to the microcontroller.