Interior GPS navigation

• US 5,959,575 A
• Filed: 11/04/1997
• Issued: 09/28/1999
• Est. Priority Date: 11/04/1997
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Abbott, Anthony Steven
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/964,083
• Time in Patent Office: 693 Days
• Field of Search: 342/257, 342/357.06, 701/213
• US Class Current: 342/357.31
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/15 Aircraft landing systems

Abstract

A method for indoor navigation is disclosed. The method comprises the following steps: (a) disposing a plurality of ground transceivers in proximity of an indoor area to be navigated through; (b) transmitting from each of the ground transceivers a pseudo-satellite signal which includes positional coordinates of the ground transceiver and an assigned PRN code sequence modulated on an L-band carrier signal having a frequency approximately equal to an L1 frequency of global positioning system (GPS) satellite signals, the assigned PRN code sequence being different from PRN code sequences that are included in GPS satellite signals; (c) receiving the pseudo-satellite signals with a receiver circuit of a mobile GPS receiver, the receiver circuit including a code generator circuit for producing internal PRN code sequences; (d) comparing the internal PRN code sequences with PRN code sequences included in the pseudo-satellite signals to derive decoded pseudo-satellite signals, using a decoder circuit of the mobile GPS receiver; (e) processing the decoded pseudo-satellite signals using a processing circuit of the mobile GPS receiver; and (f) deriving positional coordinates of the mobile GPS receiver from the processed decoded pseudo-satellite signals.

Claims

1. A method for indoor navigation, the method comprising the steps of:

(a) generating pseudo-satellite signals from a plurality of pseudo-satellite ground transceivers, said method of generating said pseudo-satellite signals comprising the steps of;

(1) generating a signal having a unique code for each around transceiver;

(2) combining said signal with navigation data of the transceiver to generate a resulting signal; and

(3) modulating said resulting signal within a carrier band to generate the pseudo-random satellite signals;

(b) transmitting from each of the ground transceivers said pseudo-satellite signals;

(c) receiving the pseudo-satellite signals with a receiver circuit of a mobile GPS receiver, the receiver circuit including a memory circuit for storing the unique code of the ground transceivers;

(d) comparing the stored codes with the pseudo-satellite signals to derive decoded pseudo-satellite signals, using a decoder circuit of the mobile GPS receiver;

(e) processing the decoded pseudo-satellite signals using a processing circuit of the mobile GPS receiver; and

(f) deriving positional coordinates of the mobile GPS receiver from the processed decoded pseudo-satellite signals.

2. The method as recited in claim 1 further comprising the steps of:

(a) receiving GPS satellite signals having each a PRN code sequence included therein, at each of the plurality of ground transceivers, with a receiver circuit of the ground transceiver, the receiver circuit including a code generator circuit for producing internal PRN code sequences;

(b) comparing the internal PRN code sequences with PRN code sequences included in the GPS satellite signals to derive decoded GPS satellite signals, utilizing a decoder circuit of the ground transceiver;

(c) processing the decoded GPS satellite signals with a processing circuit of the ground transceiver; and

(d) deriving positional coordinates of the ground transceiver from the processed decoded GPS satellite signals.

3. The method as recited in claim 2 further comprising the steps of:

(a) positioning at least one of the ground transceivers at a fixed known location to serve as a reference ground transceiver;

(b) computing differential GPS position correction information by calculating differences between positional coordinates of the reference ground transceiver as determined from information in the GPS satellite signals and positional coordinates of the reference ground transceiver as determined by the fixed known location;

(c) transmitting the differential GPS position correction information from the reference ground transceiver to other ground transceivers in the plurality of ground transceivers; and

(d) correcting positional coordinates of each of the ground transceivers as derived from the decoded GPS satellite signals, using the differential GPS position correction information.

4. The method as recited in claim 1 wherein each pseudo-satellite signal comprises a navigation message portion including positional coordinates of a ground transceiver and time at which the pseudo-satellite signal is transmitted by the ground transceiver.

5. A ground-based navigation system for receiving global positioning system (GPS) satellite signals and broadcasting pseudo-satellite signals, the system comprising a plurality of ground transceivers, each of the ground transceivers comprising:

a receiver circuit for receiving GPS satellite signals;

a decoding circuit for decoding the GPS satellite signal;

a processing circuit for processing the decoded GPS satellite signals and deriving therefrom positional coordinates of the ground transceiver;

a pseudo-satellite signal generating circuit comprising;

(a) a signal generation circuit utilizing a unique code for each ground transceiver;

(b) a gate circuit for combining said signal with said decoded GPS satellite signal to generate a resulting signal; and

(c) a modulation circuit for combining said resulting signal with a carrier signal to generate the pseudo-satellite signal; and

a transmitter circuit for transmitting a pseudo-satellite signal.

6. The system as recited in claim 5 further comprising a mobile GPS receiver utilizing GPS satellite signals for outdoor navigation and utilizing pseudo-satellite signals for indoor navigation, the mobile GPS receiver including:

a receiver circuit for receiving the GPS satellite signals and the pseudo-satellite signals, the receiver circuit including a code generator circuit operative to generate internal PRN code sequences and a decoder circuit for comparing the internal PRN code sequences with PRN code sequences included in the received GPS satellite signals and with PRN code sequences included in the pseudo-satellite signals, the decoder circuit being operative to derive decoded GPS satellite signals and decoded pseudo-satellite signals; and

a processing circuit for processing the decoded GPS satellite signals and deriving therefrom positional coordinates of the mobile GPS receiver for outdoor navigation, and for processing the decoded pseudo-satellite signals and deriving therefrom positional coordinates of the mobile GPS receiver for indoor navigation.

7. The system as recited in claim 5 wherein the plurality of ground transceivers comprises at least one reference ground transceiver positioned at a fixed known location, said reference ground transceiver including a reference location circuit for computing differential GPS position correction information by calculating differences between positional coordinates of the reference ground transceiver as derived from the decoded GPS satellite signals and positional coordinates of the reference ground transceiver as determined by the fixed known location, said reference ground transceiver transmitting a differential GPS position correction information signal to other ground transceivers in the plurality of ground transceivers, and wherein each of the ground transceivers comprises a position correction circuit operative to correct positional coordinates of the ground transceiver as derived from the decoded GPS satellite signals.

8. The system as recited in claim 5 wherein each pseudo-satellite signal comprises a navigation message portion including positional coordinates of a ground transceiver and the time at which the pseudo-satellite signal is transmitted by the ground transceiver.

9. The system as recited in claim 6 wherein the mobile GPS receiver further comprises a transmitter circuit for transmitting positional coordinates of the mobile GPS receiver in response to receipt of a querying signal.

10. A method for precision landing for an aircraft utilizing global positioning system (GPS) satellite signals, the GPS satellite signals having each a pseudo-random noise (PRN) code sequence included therein, the method comprising the steps of:

(a) generating pseudo-satellite signals from a plurality of pseudo-satellite ground transceivers, said method of generating said pseudo-satellite signals comprising the steps of;

(1) generating a unique code for each ground transceiver;

(2) combining said signal with navigation data of the transceiver to generate a resulting signal; and

(3) modulating said resulting signal within a carrier band to generate the pseudo-random satellite signals;

(b) transmitting from each of the ground transceivers said pseudo-satellite signals;

(c) receiving the GPS satellite signals and the pseudo-satellite signals with a receiver circuit of a GPS receiver positioned on the aircraft, the receiver circuit including a memory circuit for storing the unique code of the ground transceivers;

(d) comparing the stored codes with the received GPS satellite signals to derive decoded GPS satellite signals, and to derive decoded pseudo-satellite signals, using a decoder circuit of the mobile GPS receiver;

(e) processing the decoded GPS satellite signals and deriving therefrom positional coordinates of the receiver for aircraft navigation while being far from the landing location; and

(f) processing the decoded pseudo-satellite signals and deriving therefrom positional coordinates of the receiver for aircraft navigation while being near the landing location.

11. The method as recited in claim 10 further comprising the steps of:

(a) receiving the GPS satellite signals at each of the plurality of ground transceivers, with a GPS receiver circuit of the ground transceiver, the GPS receiver circuit including a code generator circuit for producing internal PRN code sequences;

(b) comparing the internal PRN code sequences with PRN code sequences included in the GPS satellite signals to derive decoded GPS satellite signals, utilizing a decoder circuit of the ground transceiver;

(c) processing the decoded GPS satellite signals using a processing circuit of the ground transceiver; and

(d) deriving positional coordinates of the ground transceiver from the processed decoded GPS satellite signals.

12. The method as recited in claim 11 further comprising the steps of:

(a) positioning at least one of the ground transceivers at a fixed known location to serve as a reference ground transceiver;

(b) computing differential GPS position correction information by calculating differences between positional coordinates of the reference ground transceiver as derived from the decoded GPS satellite signals and positional coordinates of the reference ground transceiver as determined by the fixed known location;

(c) transmitting the differential GPS position correction information from the reference ground transceiver to other ground transceivers in the plurality of ground transceivers; and

(d) correcting positional coordinates of each of the ground transceivers as derived from the decoded GPS satellite signals, using the differential GPS position correction information.

13. The method as recited in claim 10 wherein each pseudo-satellite signal comprises a navigation message portion including positional coordinates of the ground transceiver and time at which the pseudo-satellite signal is transmitted by the ground transceiver.

14. A system for precision landing for an aircraft utilizing global positioning system (GPS) satellite signals, the system comprising:

(a) a plurality of ground transceivers disposed in proximity of a landing location, each of the ground transceivers comprising;

a GPS receiver circuit for receiving GPS satellite signals;

a decoding circuit for decoding the GPS satellite signal;

a processing circuit for processing the decoded GPS satellite signals and deriving therefrom positional coordinates of the ground transceiver;

a pseudo-satellite signal generating circuit comprising;

(a) a signal generation circuit utilizing a unique code for each ground transceiver;

(b) a gate circuit for combining said signal with said decoded GPS satellite signal to generate a resulting signal; and

(c) a modulation circuit for combining said resulting signal with a carrier signal to generate the pseudo-satellite signal; and

a transmitter circuit for transmitting a pseudo-satellite signal;

a transmitter circuit for transmitting a pseudo-satellite signal; and

(b) a GPS receiver positioned on the aircraft, the GPS receiver comprising;

a receiver circuit for receiving the GPS satellite signals and the pseudo-satellite signals, the receiver circuit including a code generator circuit operative to generate internal PRN code sequences and a decoder circuit for comparing the internal PRN code sequences with PRN code sequences included in the received GPS satellite signals and with PRN code sequences included in the received pseudo-satellite signals, the decoder circuit being operative to derive decoded GPS satellite signals and decoded pseudo-satellite signals; and

a processing circuit for processing the decoded GPS satellite signals and deriving therefrom positional coordinates of the GPS receiver for aircraft navigation while being far from the landing location, and for processing the decoded pseudo-satellite signals and deriving therefrom positional coordinates of the GPS receiver for aircraft navigation while being near the landing location.

15. The system as recited in claim 14 wherein the ground transceivers comprises at least one reference ground transceiver positioned at a fixed known location, said reference ground transceiver including a reference location circuit for computing differential GPS position correction information by calculating differences between positional coordinates of the reference ground transceiver as derived from the decoded GPS satellite signals and positional coordinates of the reference ground transceiver as determined by the fixed known location, said reference ground transceiver transmitting the differential GPS position correction information to other ground transceivers in the plurality of ground transceivers, and wherein each of the ground transceivers comprises a position correction circuit operative to correct positional coordinates of the ground transceiver as derived from the decoded GPS satellite signals, using the differential GPS position correction information.

16. The system as recited in claim 14 wherein each pseudo-satellite signal comprises a navigation message portion including positional coordinates of a ground transceiver and time at which the pseudo-satellite signal is transmitted by the ground transceiver.

17. A global positioning system (GPS) receiver for navigation in either an orbital satellite GPS environment or a pseudo-satellite local area navigation system environment comprising:

a receiver circuit for accepting carrier band signals from GPS satellite and local area navigation pseudo-satellites;

a comparator circuit for comparing received carrier band signals with stored code sequences to identify the source of the carrier band signal;

a decoder circuit for demodulating said received carrier band signal to generate navigational information; and

a processing circuit for calculating the location of the receiver from said navigational information and the source of the carrier band signals.