US 5,510,798 A · Multiple-accuracy GPS system

Abstract

A GPS system for both generating and receiving multiple differential corrections from a single broadcast transmission may involve FM subcarrier modulations at any carrier frequency or subcarrier offset to provide multiple differential correction signals having varying accuracy. Signals may be encrypted and enabled through a controllable address signal to be provided on a subscription basis. Subcarrier transmissions are provided for in overlapping manner for redundancy and with either separate or interleaved differential signals so as to be able to both broadcast differential corrections and informational signals using existing equipment and FM stations at any available offset with both uplink and downlink capabilities. Similarly at least one FM receiver component is included within a traditional GPS receiver to simultaneously receive, scan, locate, and compare differential signals for more accurate determination of location in a reliable and optimum manner and at differing locations.

Claims28

Dependent claims

A method of accurately determining position using Navstar Global Position System (GPS) signals comprising the steps of:

a. receiving said GPS signals at a known location;
b. calculating a GPS signal-indicated location from said signals;
c. comparing said GPS signal-indicated location with said known location;
d. creating a first composite differential correction set indicative of a first correction with respect to said GPS signals in response to said step of comparing;
e. creating at least a second composite differential correction set in response to said step of comparing wherein said second composite differential correction set is independent from said first composite differential correction set, wherein said second differential correction set is indicative of a second correction with respect to said GPS signals, and wherein said second correction is different from said first correction;
f. disseminating said independent differential correction sets by transmission through electromagnetic broadcast;
g. receiving at least one of said differential correction sets at an unknown location;
h. receiving said GPS signals at said unknown location;
and
i. utilizing said differential correction set and said GPS signals to determine the location of said unknown location.

7 more elements

A system for accurately determining position using Navstar Global Position System (GPS) signals comprising:

a. a first receiver situated at a known location and responsive to said GPS signals;
b. a first processor responsive to said first receiver;
c. a comparison means responsive to said first processor which creates a comparative representation based upon said GPS signals and data representative of said known location;
d. a signal generator responsive to said comparative representation which creates a first composite differential correction set indicative of a first correction;
e. a signal generator responsive to said comparative representation which creates at least a second composite differential correction set, wherein said second composite differential correction set is independent from said first composite differential correction set, wherein said second differential correction set is indicative of a second correction, and wherein said second correction is different from said first correction;
f. an electromagnetic broadcast transmitter responsive to said first independent differential correction set;
g. an electromagnetic broadcast transmitter responsive to said at least second independent differential correction set;
h. a second receiver responsive to said GPS signals;
i. a differential correction receiver responsive to at least one of said electromagnetic broadcasts;
and
j. a second processor responsive to both said differential correction receiver and said second receiver and capable of determining the location of said second receiver.

8 more elements

Dependencies are inferred from the claim text.

Multiple-accuracy GPS system

Life of this patent

Multiple-accuracy GPS system

Life of this patent

Abstract

Claims28