Systems and methods for communication in a global positioning system (GPS) device

• US 7,839,916 B1
• Filed: 10/08/2004
• Issued: 11/23/2010
• Est. Priority Date: 10/08/2003
• Status: Expired due to Fees

• Current Assignee: L3harris Interstate Electronics Corporation (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Inventors: Nicosia, Joseph M., Luecke, James R.
• Primary Examiner(s): Payne; David C
• Assistant Examiner(s): NGUYEN, LEON VIET Q
• Application Number:
  US10/962,165
• Time in Patent Office: 2,237 Days
• Field of Search: 375/140, 375/142, 375/147, 375/150, 342/357.06, 342/357.1
• US Class Current: 375/147
• CPC Class Codes: G01S 19/12 wherein the cooperating elements are telecommunication base stations
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/31 Acquisition or tracking of other signals for positioning
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04B 1/71632 Signal aspects H04B1/7172 and H04B1/7176 take precedence
• CPC Class Codes: H04B 2201/71636 Transmitted reference

Abstract

An apparatus and methods for communicating between or among global positioning system (GPS) receivers enhanced with wideband transmitters, which can include ultra wideband (UWB) transmitters. In one embodiment, WB pulses are precorrected by a transmitter to align with a clock common to both enhanced GPS receivers for autocorrelation, thereby simplifying WB or UWB receiver circuitry. One embodiment includes a circuit and method for adjusting the timing of a pulse by phase shifting the pulse by adjusting amplitude. The wideband pulses are used to communicate data between enhanced GPS receivers. A relatively long code can also be communicated between enhanced GPS receivers, thereby permitting the same WB signal to be used to determine range between the enhanced GPS receivers. The communicated data can include the absolute position of the enhanced GPS receiver, which when combined relative positioning from ranging data, can advantageously permit cooperatively positioning and/or navigation.

Claims

1. A method of timing the transmission of symbols of a local direct-sequence spread spectrum (DSSS) signal, wherein the local DSSS signal is sent from a first transceiver to a second transceiver, the method comprising:

receiving at least sporadically, one or more satellite navigation signals in the first transceiver such that the first transceiver is synchronized with satellite system time;

receiving, at least sporadically, one or more satellite navigation signals in the second transceiver such that the second transceiver is synchronized with satellite system time; and

under control of a processor of the first transceiver, modulating or pulsing symbols of the local DSSS signal such that the symbols are transmitted by a transmitter and antenna of the first transceiver with actively precorrected timing so that when the symbols of the local DSSS signal are received in the second transceiver that is separate from the first transceiver, the symbols are received with substantially zero offset relative to boundaries of a clock signal based on satellite system time even when a distance between the first transceiver and the second transceiver changes;

generating the clock signal based on satellite system time in the second transceiver;

using one or more boundaries of the clock signal as timing references for sampling windows wherein the sampling windows are aligned with substantially zero offset relative to the boundaries of the clock signal based on satellite system time; and

using the sampling windows to sample the DSSS signal.

2. The method as defined in claim 1, wherein the clock signal is Global Positioning System (GPS) system time, and the DSSS signal is an ultra wideband (UWB) signal.

3. The method as defined in claim 1, wherein the clock signal is Global Positioning System (GPS) system time, and the DSSS signal is an RF carrier wave modulated by wideband (WB) impulses.

4. The method as defined in claim 1, wherein the DSSS signal corresponds to a pseudorandom noise (PN) ranging code, further comprising using the PN ranging code to determine a range to a source of the DSSS signal.

5. The method as defined in claim 1, wherein the DSSS signal corresponds to a pseudorandom noise (PN) ranging code, further comprising modulating the PN ranging code to encode a message.

6. The method as defined in claim 5, wherein the encoded message includes an absolute position of a source for the DSSS signal.

7. A method of timing the transmission of symbols of a local direct-sequence spread spectrum (DSSS) signal, wherein the local DSSS signal is sent from a first transceiver to a second transceiver, the method comprising:

providing the first transceiver, wherein the first transceiver is capable of adjustably offsetting symbols of the local DSSS signal relative to satellite system time when transmitted by the first transceiver;

providing the second transceiver, wherein the second transceiver is separate from the first transceiver;

receiving at least sporadically, one or more satellite navigation signals in the first transceiver such that the first transceiver is synchronized with satellite system time;

receiving, at least sporadically, one or more satellite navigation signals in the second transceiver such that the second transceiver is synchronized with satellite system time; and

under control of a processor of the first transceiver, modulating or pulsing symbols of the local DSSS signal such that the symbols are transmitted by a transmitter and antenna of the first transceiver with actively corrected timing so that when the symbols of the local DSSS signal are received in the second transceiver, the symbols are received with substantially zero offset relative to boundaries of a clock signal based on satellite system time even when the first transceiver and the second transceiver are moving relative to each other.

8. A method of timing a local direct-sequence spread spectrum (DSSS) signal, wherein the local DSSS signal is sent from a first device to a second device, the method comprising:

receiving one or more satellite navigation signals in the first device;

receiving one or more satellite navigation signals in the second device;

sending symbols of the local DSSS signal from the first device to the second device such that the symbols of the local DSSS signal are substantially time-aligned with a predetermined offset from satellite system time, wherein the local DSSS signal includes a pseudorandom noise (PN) ranging code;

acquiring the local DSSS signal in the second device with a correlator circuit;

computing a first offset in the local DSSS signal relative to the satellite system time; and

sending a second local DSSS signal from the second device to the first device, wherein the second local DSSS signal is deliberately offset by the second device from the satellite system time such that a second offset in timing in the second local DSSS signal relative to the satellite navigation signal as received in the first device is less than the first offset.

9. The method as defined in claim 8, further comprising determining a range from the second device from the PN ranging code and using the range to compute a propagation delay.

10. A method in a first node of determining range to a second node, the method comprising:

at least sporadically receiving satellite ranging codes in the first node so that the first node is synchronized to satellite system time;

receiving ultra wideband (UWB) pulses transmitted from the second node, wherein the second node is also synchronized to satellite system time, wherein the UWB pulses encode a pseudorandom noise (PN) ranging code that is synchronized with satellite system time when transmitted by the second node;

determining an offset in the first node based on the PN ranging code originally sent by and received from the second node and satellite system time;

using the offset to determine range from the first node to the second node; and

retrieving an absolute position of the second node encoded on the PN ranging code, and using the range to the second node and the absolute position of the second node to supplement positioning of the first node obtained via Global Positioning System (GPS).

11. A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein each node of the plurality of nodes is synchronized to GPS system time, wherein each node;

transmits UWB pulses encoding a particular pseudorandom noise (PN) ranging code, wherein the PN ranging code is synchronized with GPS system time when transmitted;

determines an offset between a received PN ranging code originating from another node of the plurality of nodes and GPS system time to determine range from the node that sent the PN ranging code;

using the ranges to resolve relative positioning at least with respect to the second node, wherein the second node is aware of an absolute position via GPS;

receiving an indication of the absolute position of the second node; and

combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node.

12. A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein ranging is performed using UWB pulses encoding a pseudorandom noise (PN) ranging code, wherein the range between the first node and the second node is cooperatively determined by communication in both directions to and from the first node and the second node, wherein the second node is aware of an absolute position;

using the ranges to resolve relative positioning at least with respect to the second node;

receiving an indication of the absolute position of the second node;

combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node;

determining relative positioning to one or more additional nodes;

receiving indications of the absolute positions of the one or more additional nodes; and

combining the relative positioning and the absolute positions of the one or more additional nodes to compute one or more additional indirectly-calculated absolute positions.

14. The method as defined in claim 12, wherein the absolute position of the second node is obtained via satellite navigation.

15. The method as defined in claim 12, wherein the absolute position of the second node is derived from an inertial measurement unit (IMU).

16. The method as defined in claim 12, further comprising communicating with the second node to receive the absolute position of the second node.

17. The method as defined in claim 12, further comprising:

modulating a PN ranging code to communicate a message, wherein the message includes an indication of the absolute position; and

determining range using the pseudorandom noise (PN) ranging code.

21. The method as defined in claim 12, wherein none of the plurality of nodes correspond to a space vehicle of a satellite positioning system, wherein the ranges are determined with greater precision than is attainable from a satellite positioning system.

13. A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein the range between the first node and the second node is cooperatively determined by communication in both directions to and from the first node and the second node, wherein the second node is aware of an absolute position;

using the ranges to resolve relative positioning at least with respect to the second node;

receiving an indication of the absolute position of the second node;

combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node;

computing a second absolute position for the first node via satellite navigation; and

combining the second absolute position with the indirectly-calculated absolute position of the first node using an unequal weighting to generate an aggregate absolute position, wherein weights are at least partially based on an estimated clock error.

18. A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein ranging is performed using UWB pulses encoding a pseudorandom noise (PN) ranging code, wherein the range between the first node and the second node is cooperatively determined by communication in both directions to and from the first node and the second node, wherein the second node is aware of an absolute position;

using the ranges to resolve relative positioning at least with respect to the second node;

receiving an indication of the absolute position of the second node;

combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node;

computing a second absolute position for the first node via satellite navigation; and

combining the second absolute position with the indirectly-calculated absolute position of the first node to generate an aggregate absolute position.

19. The method as defined in claim 18, further comprising combining via averaging.

20. The method as defined in 13, wherein ranging is performed using UWB pulses encoding a pseudorandom noise (PN) ranging code.