Motorola Corporation

John D Wetters

Raul Salvi

M William Branan, Jr

John Wayne Simmons

Wayne M Phang

Virgilio A Fernandez

Steve Carsello

Art Ahrens

A selective call receiver (100) for receiving and transmitting paging signals has a transceiver (104) having an integer divide synthesizer (105) for achieving a fast lock time. The transceiver (104) has a reference oscillator (202) that generates a reference signal in a direct injection path and a modulator (206) coupled in the direct injection path modulates the reference signal to generate a modulated reference signal. A phase locked offset loop (220) coupled to the direct injection path generates a low frequency signal derived from the reference signal, a multiplier (210) coupled to the modulator (206) multiplies the modulated reference signal, and a mixer (214) coupled to the multiplier (210) receives the modulated reference signal in the direct injection path and an output signal from the phase locked offset loop (220) to generate a first local oscillator output signal and a modulated transmit carrier.

Selective call receivers with integer divide synthesizers for achieving

A method of calibrating a radio receiver (100) which has a desired IF center frequency (fo) includes generating and applying to the receiver's demodulator (126) a plurality of reference signals. The demodulated reference signals are used to generate, for the demodulator, a transfer function that is predictive of amplitude versus frequency characteristics of signals to be demodulated by the demodulator (126). The transfer function (202) is used to determine a frequency offset between a received signal's intermediate frequency and the desired frequency fo. The determined frequency offset is used to adjust the IF frequency of the received signal towards the desired frequency fo. The adjustment process preferably continues until the frequency offset is below a desired threshold. A receiver using the disclosed method is also described.

Radio receiver and method of calibrating same

A transceiver synthesizer includes components that enable it to be tuned non-invasively by software. The transceiver synthesizer includes a non-volatile memory (30) that can be non-invasively programmed with a digital value for each of a number of tuning variables. The digital values are converted by digital to analog converters (37, 38, 39) into tuning voltages. The tuning voltages are applied to voltage variable devices (60, 80, 95) that respond to changes in the applied tuning voltage to vary an operating characteristic thereof. The operating characteristics of the voltage variable devices (60, 80, 95) are non-invasively adjustable to tune the transceiver synthesizer for high and low port modulation deviation, reference oscillator make tolerance, automatic frequency control, reference oscillator temperature compensation etc.

System and method for providing a non-invasively tunable transceiver

A digital squelch system (100) includes a timing signal generator (102) for generating a reference window. An edge detector (106) detects edges in the input signal during this reference window. An accumulator (110) accumulates the number of coherencies. An overflow detector (112) coupled to the accumulator (110) detects overflow conditions therein. A latch coupled to the overflow detector (112) squelches and unsquelches the radio (200) when the overflow or underflow conditions have been detected, respectively.

Digital squelch circuit

A radio device (10) receives optical control signals from a remote control apparatus (22). In one embodiment, both the radio device and remote control apparatus include optical transmitters (58) and receivers (60) so that control and information signals may provided to and received from the radio's operator. In another embodiment, the radio () provides a light signal to the remote control apparatus () that either permits or prohibits (80) the light signal's return to the radio. In this way, the presence or absence of the return light signal comprises optical control signals to control the radio's operation.

Optically controlled radio

A light source (124) is used to transmit a light signal down an optical communication channel (12). In a light-reflective embodiment of the present invention, a portion of the transmitted light signal is reflected back (20) into the optical communication channel (12) to an optical receiver (126). By measuring the intensity of the reflected light, one or more operational parameters of the radio can be controlled (106). In a light-transmissive embodiment of the present invention a portion of the transmitted light signal is allowed to pass to the end of the communication channel. By measuring the intensity of the light reaching the end of the optical communicaton channel, one or more operational parameters of the radio can be controlled.

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Coral Springs, FL, United States of America

John D Wetters