US 5,970,400 AGranted

Adjusting the timing and synchronization of a radio's oscillator with a signal from an SATPS satellite

AssigneeMagellan Corporation

InventorRex Dwyer

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Abstract

A communication system is provided for increasing communication range between at least two radio communication devices without increasing the output power of transmitted radio signals from the devices, and without increasing the antenna gain of the received signals. Each radio device includes an oscillator for generating a carrier reference signal, and an SATPS receiver which receives at least one standard timing reference signal from at least one SATPS satellite. The received standard timing reference signal is used to continuously adjust the timing and synchronization of the oscillator to improve the accuracy of the carrier frequency signal. The improved accuracy in the carrier frequency signal may then be used to reduce the bandwidth of the modulated carrier frequency signals generated by the radio device to thereby increase the effective communication range and sensitivity of the device.

Claims24

Dependent claims

A portable, wireless radio communication system comprising:

at least one wireless spread spectrum radio communication device, said device including an oscillator for generating a clock signal and a carrier frequency signal, said carrier frequency signal having a predetermined frequency stability and further having a predetermined carrier minimum bandwidth determined by the extreme frequency excursion of said oscillator;
a channel filter accommodating a predetermined channel bandwidth only slightly larger than said predetermined carrier minimum bandwidth;
a SATPS receiver in communication with the radio device, wherein the SATPS receiver receives at least one standard timing reference signal from at least one SATPS satellite;
and
correction means for using said timing reference signal to continuously adjust and improve the accuracy of said carrier frequency reference signal, said correction means increasing the frequency stability of said carrier frequency signal to a level higher than said predetermined frequency stability while also simultaneously reducing the channel bandwidth of said channel filter to a value smaller than that of said predetermined channel bandwidth and that of said predetermined carrier minimum bandwidth.

2 more elements

A method for improving communication range of a spread spectrum radio communication system, said system including a mobile spread spectrum radio communication device including an oscillator for generating a carrier frequency signal, said carrier frequency signal having a predetermined carrier minimum bandwidth determined by the extreme frequency excursions of said oscillator, and a channel filter accommodating a predetermined channel bandwidth only slightly larger than said predetermined carrier minimum bandwidth, said system further including an SATPS receiver, said method comprising the steps of:

(a) receiving at least one standard timing reference signal from at least one SATPS satellite,
(b) using said received timing reference signal to continually correct and maintain precise timing and synchronization of said oscillator to thereby provide improved accuracy of said carrier frequency signal;
and
(c) utilizing the improved accuracy of the carrier frequency signal to increase the frequency stability of said carrier frequency signal to a level higher than said predetermined frequency stability while also simultaneously reducing the channel bandwidth of said channel filter to a value smaller than that of said predetermined channel bandwidth and that of said predetermined carrier minimum bandwidth.

1 more element

In a portable, wireless radio communication system having a reference oscillator generating a clock signal and a carrier signal, said carrier signal frequency having a predetermined frequency stability and further having a predetermined carrier minimum bandwidth determined by the extreme frequency excursions of said oscillator, and a channel filter accommodating a predetermined channel bandwidth only slightly larger than said predetermined carrier minimum bandwidth, the improvement comprising:

at least one wireless spread spectrum radio communication device having said reference oscillator and said channel filter,
a SATPS receiver in communication with said at least one radio device, wherein the SATPS receiver receives at least one standard timing reference signal from at least one SATPS satellite;
and
a correction circuit responsive to said timing reference signal and coupled to said reference oscillator and said channel filter, said correction circuit increasing the frequency stability of said carrier signal to a level higher than said predetermined frequency stability while also simultaneously reducing the channel bandwidth of said channel filter to a value smaller than that of said predetermined channel bandwidth and that of said predetermined carrier minimum bandwidth.

1 more element

Dependencies are inferred from the claim text.