GNSS reference for subscribed precisions

• US 10,031,233 B2
• Filed: 11/25/2015
• Issued: 07/24/2018
• Est. Priority Date: 11/13/2012
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Inc.
• Inventors: Bird, David G.
• Primary Examiner(s): Liu, Harry K
• Application Number:
  US14/952,801
• Publication Number:
  US 20160154107A1
• Time in Patent Office: 972 Days
• Field of Search: 34235741, 342386, 34235742, 34235746
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/074 providing integrity data, e.g. WAAS

Abstract

This application discloses a GNSS reference apparatus having a vector error generator and a reference data server. The vector error generator generates one or more sequences of keyed intentional errors made confidential with confidential error keys, and then combines the sequences to generate a sequence of reference erroneous positions. The reference data server issues GNSS position-determination reference data based on the reference erroneous positions where the keyed intentional errors for at least one of the confidential sequences are reversible with confidential access to the corresponding confidential error key for determining a GNSS-based position.

Claims

1. A GNSS reference apparatus comprising:

a confidential key generator for generating one or more confidential error keys;

a vector error generator coupled to the confidential key generator and configured to;

generate one or more keyed intentional error vectors based on the one or more confidential error keys, respectively; and

generate a sequence of reference erroneous positions by combining the one or more keyed intentional error vectors and a true reference position, wherein the true reference position is a pre-determined known reference position; and

a reference data server coupled to the vector error generator and configured to;

generate GNSS position-determination reference data based on the sequence of reference erroneous positions; and

transmit the GNSS position-determination reference data to a GNSS rover to enable the GNSS rover to determine a subscribed rover position by reversing at least one of the one or more keyed intentional error vectors using a corresponding one of the one or more confidential error keys.

2. The GNSS reference apparatus of claim 1, further comprising:

a synthetic reference carrier phase processor coupled to the vector error generator and the reference data server, the synthetic reference carrier phase processor configured to receive GNSS signals and to synthesize GNSS reference carrier phases for the sequence of reference erroneous positions from the GNSS signals, and wherein the reference data server is configured to provide the synthesized GNSS reference carrier phases in the GNSS position-determination reference data.

3. The GNSS reference apparatus of claim 1, further comprising:

a subscribed precision catalog to classify the one or more confidential error keys as subscribed confidential error keys or non-subscribed confidential error keys, and the corresponding one or more keyed intentional error vectors as subscribed keyed intentional error vectors or non-subscribed keyed intentional error vectors; and

a confidential key messenger to enable confidential access for the subscribed confidential error keys for the GNSS rover to determine the subscribed rover position with a subscribed precision resulting from the non-subscribed keyed intentional error vectors.

4. The GNSS reference apparatus of claim 3, wherein:

the confidential key messenger includes;

a public key receiver to receive first and second rover public keys for first and second GNSS rovers, respectively, wherein the first rover public key is associated with a first rover private key for a first GNSS rover and the second rover public key is associated with a second rover private key for a second GNSS rover;

a confidential key encrypter to encrypt first and second sets of the subscribed confidential error keys with the first and second rover public keys, respectively; and

a subscription key transmitter to issue the encrypted first and second subscribed confidential error key sets for decryption with the first and second rover private keys for GNSS position-determination only for the first and second GNSS rovers, respectively.

5. The GNSS reference apparatus of claim 1, wherein:

the GNSS position determination reference data is composed so that, if the GNSS rover has confidential access to a first but not a second confidential error key, the GNSS position determination reference data enables the GNSS rover to determine the subscribed rover position with a precision degraded by the second but not the first keyed intentional error vector.

6. The GNSS reference apparatus of claim 1, wherein:

the vector error generator includes a first error encoder and a second vector error encoder to use a first and a second of the confidential error keys to generate a first and a second of the keyed intentional error vectors, respectively; and

a vector summer to combine the first and second keyed intentional error vectors with the true reference position to generate the sequence of reference positions.

7. The GNSS reference apparatus of claim 6, wherein:

the GNSS position determination reference data is composed for confidential access to the first but not the second confidential error key to confine a maximum positional error to be greater than a maximum positional error of the true reference position but less than a maximum positional error corresponding to the sequence of reference erroneous positions.

8. The GNSS reference apparatus of claim 1, wherein:

the vector error generator includes subscription filters associated with the one or more confidential error keys to filter the one or more keyed intentional error vectors, respectively; and

a position spread filter to filter the sum of the one or more keyed intentional errors vectors, a combination of a particular one of the subscription filters and the position spread filter constructed to distribute a particular one of the one or more keyed intentional error vectors into a spread associated with a corresponding particular one of the one or more confidential error keys.

9. The GNSS reference apparatus of claim 8, wherein:

the subscription filter includes a non-linear part to confine the spread within particular error boundaries associated with the particular confidential error key.

10. The GNSS reference apparatus of claim 1, further comprising:

an intentional error parameter generator to provide intentional error parameter sets associated with the one or more confidential error keys, respectively, to define shapes and sizes of the corresponding one or more keyed intentional error vectors.

11. The GNSS reference apparatus of claim 10, wherein:

the shapes are selectable by the intentional error parameter sets as a box, a cylinder, or a sphere.

12. The GNSS reference apparatus of claim 1, further comprising:

an intentional error parameter generator to associate a particular intentional error parameter set with a particular one of the one or more confidential error keys; and

wherein;

the vector error generator includes pseudo-random sequence generators to use the particular one of the one or more confidential error keys to generate confidential pseudorandom sequences, and a vector error scaler to scale the confidential pseudo-random sequences with the particular intentional error parameter set to provide a particular one of the one or more keyed intentional error vectors having an error zone having a shape and a size controlled by the intentional error parameter set.

13. The GNSS reference apparatus of claim 1, wherein:

the vector error generator includes a seed generator to combine a non-confidential frame number with a particular one of the confidential error keys to generate a particular one of the keyed intentional error vectors as a pseudo-random sequence, wherein the pseudo-random sequence is reproducible at a GNSS rover in data frames with the non-confidential frame number and the particular confidential error key.

14. A method for providing GNSS reference data for determining a GNSS-based position, the method comprising:

generating one or more confidential error keys;

generating one or more keyed intentional error vectors based on the one or more confidential error keys, respectively;

generating a sequence of reference erroneous positions by combining the one or more keyed intentional error vectors with a true reference position, wherein the true reference position is a pre-determined known reference position;

generating GNSS position-determination reference data based on the sequence of reference erroneous positions; and

transmitting the GNSS position-determination reference data to a GNSS rover to enable the GNSS rover to determine a subscribed rover position by reversing at least one of the one or more keyed intentional error vectors using a corresponding one of the one or more confidential error keys.

15. The method of claim 14, further comprising:

receiving GNSS signals; and

synthesizing GNSS reference carrier phases for the reference erroneous positions from the GNSS signals, wherein the GNSS position-determination reference data includes the synthesized GNSS reference carrier phases.

16. The method of claim 14, further comprising:

classifying the confidential error keys and the corresponding keyed intentional error vectors as subscribed or non-subscribed; and

providing confidential access for the subscribed confidential error keys for GNSS position determination with a subscribed precision resulting from the non-subscribed keyed intentional error vectors.

17. The method of claim 16, wherein:

providing the confidential access comprises;

receiving first and second rover public keys for first and second GNSS rovers, respectively, wherein the first rover public key is associated with a first rover private key and the second rover public key is associated with a second rover key;

encrypting first and second sets of the subscribed confidential error keys with the first and second rover public keys, respectively; and

issuing the encrypted first and second subscribed confidential error key sets for decryption with the first and second private rover keys for the GNSS position determination only for the first and second GNSS rovers, respectively.

18. The method of claim 14, wherein:

the GNSS position determination reference data is composed so that confidential access to a first but not a second confidential error key enables the GNSS rover to determine the subscribed rover position with a precision degraded by the second but not the first keyed intentional error vector.

19. The method of claim 14, wherein:

generating the sequence of reference positions includes using a first and a second of the confidential error keys for generating a first and a second of the keyed intentional error vectors respectively, and combining the first and second keyed intentional error vectors with the true reference position for generating the sequence of reference erroneous positions.

20. The method of claim 19, wherein:

the GNSS position determination reference data is composed for confidential access to the first but not the second confidential error key to confine a maximum positional error for the subscribed rover position to be greater than a maximum positional error of the true reference position but less than a maximum positional error corresponding to the sequence of reference erroneous positions.

21. The GNSS method of claim 14, further comprising:

filtering the one of more keyed intentional error vectors with subscription filters respectively associated with the confidential error keys; and

filtering the sum of the keyed intentional error vectors to distribute a particular one of the keyed intentional error vector into a spread associated with a corresponding particular one of the confidential error keys.

22. The method of claim 21, wherein:

filtering includes applying a non-linear gain for confining the spread within error boundaries associated with the particular confidential error key.

23. The GNSS method of claim 14, further comprising:

providing intentional error parameter sets associated with the confidential error keys, respectively, for defining shapes and sizes of the corresponding keyed intentional error vectors.

24. The method of claim 23, wherein:

the shapes are selectable by the intentional error parameter sets as a box, a cylinder, or a sphere.

25. The method of claim 14, further comprising:

associating a particular intentional error parameter set with a particular one of the confidential error keys, and wherein;

generating the sequence of reference erroneous positions includes using the particular one of the confidential error keys for generating confidential pseudo-random sequences, and scaling the confidential pseudo-random sequences with the particular intentional error parameter set for providing a particular one of the sequence of keyed intentional error vectors having an error zone having a shape and a size controlled by the intentional error parameter set.

26. The method of claim 14, wherein:

generating the sequence of reference positions includes combining a non-confidential frame number with a particular one of the confidential error keys for generating a particular one of the keyed intentional error vectors as a pseudorandom sequence, wherein the pseudo-random sequence is reproducible at a remote site in data frames with the non-confidential frame number and the particular confidential error key.

27. An apparatus including one or more processors:

one or more memories, and one or more programs stored in the one or more memories and configured to be executed by the one or more processors, the programs comprising;

instructions for generating one or more confidential error keys;

instructions for generating one or more keyed intentional error vectors based on the one or more confidential error keys, respectively;

instructions for generating a sequence of reference erroneous positions by combining the one or more keyed intentional error vectors with a true reference position, wherein the true reference position is a pre-determined known reference position;

instructions for generating GNSS position-determination reference data based on the sequence of reference erroneous positions; and

instructions for transmitting the GNSS position-determination reference data to a GNSS rover to enable the GNSS rover to determine a subscribed rover position by reversing at least one of the one or more keyed intentional error vectors using a corresponding one of the confidential error keys.