Rebroadcasting method and system for navigation signals

• US 7,310,064 B2
• Filed: 04/29/2004
• Issued: 12/18/2007
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Novariant Incorporated (Kubota Corporation)
• Inventors: Cobb, H. Stewart, Lawrence, David G.
• Primary Examiner(s): Issing; Gregory C.
• Application Number:
  US10/837,515
• Publication Number:
  US 20050242994A1
• Time in Patent Office: 1,328 Days
• Field of Search: 342/386, 342/357.06, 342/357.08
• US Class Current: 342/386
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters

Abstract

A “synchrolite” or rebroadcasting device allows GPS or GNSS navigation signals received at one or several locations to be processed at a separate location. The signals received by the synchrolite are added to a pilot tone and then encoded with a superimposed spread-spectrum code before being rebroadcast. The superimposed code allows signals from different synchrolites to be distinguished during the navigation process.

Claims

1. A method for rebroadcasting ranging signals for use in navigation, the method comprising:

(a) receiving one or more ranging signals at an antenna, the ranging signals being code division multiplexed signals;

(b) modulating the code division multiplexed ranging signals as received in step (a) with a spreading code, the modulated code division multiplexed signals being spread by the spreading code; and

(c) transmitting the ranging signals as modulated in step (b).

2. The method of claim 1 further comprising:

(d) determining a range from each of the signals transmitted in (c) by despreading twice in sequence.

3. The method of claim 2 further comprising:

(e) determining a position as a function of time from a group of ranges determined in (d).

4. The method of claim 1 further comprising:

(d) frequency shifting the ranging signals after (a) and prior to (c).

5. The method of claim 1 wherein (a) comprises receiving ranging signals in at least one frequency band.

8. The method of claim 1 further comprising:

(d) combining the ranging signals with a pilot tone prior to (b).

9. The method of claim 8 further comprising:

(e) modulating the pilot tone prior to (d).

10. The method of claim 1 wherein (a) comprises receiving the ranging signals from a satellite selected from the group of:

a GNSS satellite and a satellitebased GNSS augmentation service.

11. The method of claim 1 wherein (a) comprises receiving the ranging signals from a land-based transmitter.

12. The method of claim 1 wherein (c) comprises intermittently transmitting.

15. The method of claim 1 wherein (a) comprises receiving the ranging signals in a first frequency band, wherein (b) comprises modulating the ranging signals with at least two different spreading codes, and wherein (c) comprises separately transmitting the modulated ranging signals for each of the at least two different spreading codes.

16. The method of claim 15 wherein (c) comprises simultaneously transmitting the modulated ranging signals from separate antennas, each of the modulated ranging signals having a substantially same frequency band.

17. The method of claim 4 further comprising:

(d) calibrating the shifting as a function of the ranging signals received in (a).

6. A method for rebroadcasting ranging signals for use in navigation, the method comprising:

(a) receiving therefore ranging signals at an antenna;

(b) modulating the ranging signals as received in step (a) with a spreading code; and

(c) transmitting the ranging signals as modulated in step (b);

wherein (a) comprises receiving ranging signals in at least two frequency bands and wherein (b) comprises modulating the ranging signals of each frequency band with a different spreading code.

7. The method of claim 6 further comprising:

(d) shifting the ranging signals of the at least two frequency bands to a single rebroadcast frequency band;

wherein (c) comprises transmitting at the rebroadcast frequency band, the transmitted signals corresponding to the ranging signals from each of the at least two frequency bands.

13. A method for rebroadcasting ranging signals for use in navigation, the method comprising:

(a) receiving one or more ranging signals at an antenna;

(b) modulating the ranging signals as received in step (a) with a spreading code; and

(c) transmitting the ranging signals as modulated in step (b);

wherein (a) comprises receiving the ranging signals with a plurality of receive antennas, the antenna being one of the plurality of antennas, wherein (b) comprises modulating the ranging signals of each of the plurality of receive antennas with a different spreading code, and wherein (c) comprises combining the plurality of modulated signals from step (b) and transmitting them through a single antenna.

14. The method of claim 13 wherein (a) comprises receiving the ranging signals at a same frequency band at each of the plurality of receive antennas;

further comprising;

(d) shifting the ranging signals to a rebroadcast frequency band;

wherein (c) comprises transmitting at the rebroadcast frequency band the modulated ranging signals for each receive antenna simultaneously.

18. A system for rebroadcasting ranging signals for use in navigation, the system comprising:

a first receive antenna to receive ranging signals operable for navigation, the ranging signals being spread spectrum signals;

a first modulator connected with the first receive antenna, the first modulator operable to modulate the spread spectrum ranging signals from the first receive antenna with a first spreading code, the modulated spread spectrum ranging signals being spread signals spread again by the spreading code; and

a first transmit antenna connected with an output of the modulator.

19. The system of claim 18 further comprising:

a mixer connected with the first modulator, the mixer operable to frequency shift the signals from the first receive antenna.

23. The system of claim 18 further comprising:

a signal combiner connected between the first receive antenna and the modulator, the signal combiner operable to combine the signals with a pilot tone.

20. A system for rebroadcasting ranging signals for use in navigation, the system comprising:

a first receive antenna to receive ranging signals operable for navigation;

a first modulator connected with the first receive antenna, the first modulator operable to modulate the ranging signals from the first receive antenna with a first spreading code; and

a first transmit antenna connected with an output of the modulator;

wherein the first modulator is operable on the signals from the first receive antenna at a first frequency band;

further comprising;

a second modulator operable on other signals at a second frequency band different than the first frequency band, the second modulator operable to modulate the other signals with a different spreading code than for the first modulator;

wherein the first transmit antenna is operable to simultaneously transmit the signals and other signals from the first and second modulators.

21. A system for rebroadcasting ranging signals for use in navigation, the system comprising:

a first receive antenna to receive ranging signals operable for navigation;

a first modulator connected with the first receive antenna, the first modulator operable to modulate the ranging signals from the first receive antenna with a first spreading code; and

a first transmit antenna connected with an output of the modulator;

wherein the first modulator is operable on the signals at a first frequency band;

further comprising;

a second receive antenna; and

a second modulator connected with the second receive antenna, the second modulator operable on signals from the second receive antenna at the first frequency band and operable to modulate the signals from the second receive antenna with a different spreading code than for the first modulator;

wherein the first transmit antenna is operable to simultaneously transmit signals from the first and second modulators.

22. A system for rebroadcasting ranging signals for use in navigation, the system comprising:

a first receive antenna to receive ranging signals operable for navigation;

a first modulator connected with the first receive antenna, the first modulator operable to modulate the ranging signals from the first receive antenna with a first spreading code; and

a first transmit antenna connected with an output of the modulator;

wherein the first modulator is operable on signals at a first frequency band;

further comprising;

a second modulator operable to modulate the signals as a function of a second spreading code different than the first spreading code; and

a second transmit antenna connected with the second modulator, the second transmit antenna operable to transmit the signals modulated by the second modulator and the first transmit antenna operable to transmit the signals modulated by the first modulator.