Receiver and method for receiving a composite signal

• US 8,942,264 B2
• Filed: 12/18/2012
• Issued: 01/27/2015
• Est. Priority Date: 10/26/2012
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Keegan, Richard G.
• Primary Examiner(s): Ngo, Ricky
• Assistant Examiner(s): SAMUEL, DEWANDA A
• Application Number:
  US13/718,837
• Publication Number:
  US 20140119360A1
• Time in Patent Office: 770 Days
• Field of Search: 370/204, 370/205, 370/313, 370/546
• US Class Current: 370/546
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: H04L 2027/0026 Correction of carrier offset
• CPC Class Codes: H04L 2027/0057 quadrature phase
• CPC Class Codes: H04L 2027/0087 Out-of-band signals, (e.g. pilots)
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657

Abstract

A multiplexer is capable of multiplexing at least two signals selected from the first signal, the second signal and the null code signal. In a first mode, the multiplexer multiplexes the first signal and the null code signal consistent with a predetermined time sequence for expression of the null code in first precursor signal In a second mode, the multiplexer multiplexes the first signal and the second signal to provide a second precursor signal. A correlator can correlate the digital received composite signal to the locally generated reference signal to decode at least a first portion of the received composite signal or the entire received composite signal, depending upon the mode (e.g., operation in the first or second mode).

Claims

1. A receiver for receiving a binary offset carrier signal, the receiver comprising:

a receiver front-end for down-converting a received composite signal;

an analog-to-digital converter for converting the received composite signal to a digital received composite signal;

a first signal generator for generating a first signal;

a second signal generator for generating a second signal;

a data storage device for providing a null code;

a multiplexer for multiplexing a first combination in a first mode or a second combination of input signals in a second mode to form a precursor signal, the first combination comprising the first signal and the null code consistent with a predetermined time sequence for expression of the null code in the precursor signal, the second combination comprising the combination of the first signal and the second signal;

a ranging code generator for generating a ranging code;

a mixer accepting the ranging code and the precursor signal and outputting a locally generated reference signal;

a code correlator for correlating the digital received composite signal to the locally generated reference signal to decode at least a first portion of the received composite signal in the first mode;

a tracking loop signal processor for processing the locally generated reference signal with respect to the digital received composite signal to maximize correlation of the received composite signal to the locally generated reference signal; and

a controller for controlling the multiplexor to operate in the first mode or in the second mode consistent with a level of service, geographic region, or time period authorized for the receiver or an end user of the receiver.

2. The receiver according to claim 1 wherein in the first mode, the code correlator is adapted to correlate the digital received composite signal to the locally generated reference signal to decode at least a first portion of the received composite signal, while leaving a second portion of the received composite signal undecoded.

3. The receiver according to claim 1 wherein in a second mode, the code correlator can correlate the digital received composite signal to the locally generated reference signal to decode completely the entire received composite signal.

4. The receiver according to claim 1 wherein, in the first mode, the received composite signal comprises a multiplexed binary offset carrier (MBOC) or a time multiplexed binary offset carrier (TMBOC) signal and wherein the predetermined time sequence is based on the time slots that a particular binary offset carrier signal component of the MBOC signal is expressed in the MBOC signal.

5. The receiver according to claim 1 wherein, in the first mode, the received composite signal comprises a multiplexed binary offset carrier (MBOC) or a time multiplexed binary offset carrier (TMBOC) signal and wherein the predetermined time sequence is based on the time slots that a MBOC (6,1) signal is expressed in the MBOC signal.

6. The receiver according to claim 1 further comprising:

in the first mode, a controller for controlling the selection of time slots provided to multiplexer input terminals of the multiplexer based on reference to the predetermined time sequence to produce, at the multiplexer output terminal, the precursor signal of a modified BOC (1,1) modified such that a minority fraction of the precursor of the BOC (1,1) has null codes.

7. The receiver according to claim 1 wherein the data storage device comprises one or more of the following:

a latch, a register, a flip-flop, electronic memory, or nonvolatile electronic memory.

8. The receiver according to claim 1 wherein the null code comprises a voltage at or approaching zero volts and wherein the first signal has a maximum positive amplitude and a maximum negative amplitude such that the maximum positive amplitude is associated with a first logic level and the maximum negative amplitude is associated with a second logic level that is the opposite of the first logic level.

9. The receiver according to claim 1 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) signal composed of a binary offset carrier (BOC) (1,1) signal component, and a BOC (6,1) signal component, and wherein the first signal comprises a primary signal precursor of a BOC (1,1) signal and wherein the second signal comprises a secondary signal precursor of a BOC (6,1) signal.

10. The receiver according to claim 1 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) signal composed of a binary offset carrier (BOC) (1,1) signal component, and a BOC (6,1) signal component, and wherein, in the first mode, the locally generated reference signal comprises a modified BOC (1,1) modified such that a minority fraction of the precursor of the BOC (1,1) has null codes.

11. The receiver according to claim 1 wherein the first signal generator comprises a first square wave generator for generating a first signal at a first frequency and wherein the second signal generator comprises a second square wave generator for generating a second signal at a second frequency that is greater than the first frequency.

12. The receiver according to claim 1 wherein the first signal generator comprises a sinusoidal wave generator for generating a SinBOC (1,1) signal precursor and wherein the second signal generator comprises a sinusoidal wave generator for generating a SinBOC(6,1) signal precursor.

13. The receiver according to claim 1 wherein the code correlator correlates the digital composite signal to the locally generated signal to demodulate the received composite signal.

14. The receiver according to claim 1 wherein the code correlator correlates the digital composite signal to the locally generated signal to identify edge transitions for tracking the carrier phase of the of the received composite signal.

15. The receiver according to claim 1 wherein, in the second mode or the first mode, the code correlator correlates the digital composite signal to the locally generated signal to demodulate a pilot code of the received composite signal.

16. The receiver according to claim 1 wherein, in the second mode or the first mode, the code correlator correlates the digital composite signal to the locally generated signal to demodulate any navigation data encoded in the received composite signal.

17. The receiver according to claim 1 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) signal, where a first portion of the received composite signal comprises a first binary offset carrier (BOC) (n,m) signal component, where a second portion of the received composite signal comprises a second binary offset carrier (BOC) (o,p) signal component, where n, m, o and p are integer values, and where, in a first mode the locally generated reference signal is associated with a modified BOC (n,m) signal component that is temporally dominant in a majority of the time slots of the MBOC signal, the modified BOC signal component having null codes inserted in certain time slots associated with the second BOC signal component.

18. The receiver according to claim 1 further comprising:

a data port coupled to the mode controller for programming the controller to restrict or limit the receiver to operation in the first mode for a time period.

19. A method for receiving a binary offset carrier signal, the method comprising:

down-converting a received composite signal;

converting the received composite signal to a digital received composite signal;

generating a first signal and a second signal;

providing a null code;

in a first mode comprising a first precursor signal, multiplexing the first signal and the null code consistent with a predetermined time sequence for expression of the null code in the first precursor signal;

in a second mode comprising a second percursor signal, where the second mode is mutually exclusive to the first mode, multiplexing the first signal and the second signal to produce the second precursor signal;

generating a ranging code;

accepting the ranging code and the precursor signal and outputting a locally generated reference signal, the precursor signal comprising the first precursor signal or the second precursor signal;

correlating the digital received composite signal to the locally generated reference signal to decode at least a first portion of the received composite signal; and

processing the locally generated reference signal with respect to the digital received composite signal to maximize correlation of the received composite signal to the locally generated reference signal.

20. The method according to claim 19 wherein the correlating comprises, in the first mode, correlating the digital received composite signal to the locally generated reference signal to decode at least a first portion of the received composite signal, while leaving a second portion of the received composite signal undecoded.

21. The method according to claim 19 wherein the correlating comprises, in the second mode, correlating the digital received composite signal to the locally generated reference signal to decode completely the received composite signal including the at least first portion.

22. The method according to claim 19 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) or a time multiplexed binary offset carrier (TMBOC) signal and wherein the predetermined time sequence is based on the time slots that a particular binary offset carrier signal component of the MBOC signal is expressed in the MBOC signal.

23. The method according to claim 19 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) or a time multiplexed binary offset carrier (TMBOC) signal and wherein the predetermined time sequence is based on the time slots that a BOC (6,1) signal is expressed in the MBOC signal.

24. The method according to claim 19 further comprising:

in the first mode, controlling the selection of time slots provided to multiplexer input terminals of a multiplexer based on reference to the predetermined time sequence to produce, at the multiplexer output terminal, the first precursor signal of a modified BOC (1,1) modified such that a minority fraction of the first precursor of the BOC (1,1) has null codes.

25. The method according to claim 19 wherein the providing of a null code comprises providing a null code by a data storage device.

26. The method according to claim 19 wherein the null code comprises a voltage at or approaching zero volts and wherein the first signal has a maximum positive amplitude and a maximum negative amplitude such that the maximum positive amplitude is associated with a first logic level and the maximum negative amplitude is associated with a second logic level that is the opposite of the first logic level.

27. The method according to claim 19 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) signal composed of a binary offset carrier (BOC) (1,1) signal component and a BOC (6,1) signal component, and wherein the first signal comprises a signal precursor or predecessor for formation of a BOC (1,1) signal.

28. The method according to claim 19 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) signal composed of a binary offset carrier (BOC) (1,1) signal component, and a BOC (6,1) signal component, and wherein the locally generated reference signal comprises a modified BOC (1,1) modified such that a minority fraction of a precursor or predecessor for formation of the BOC (1,1) has null codes.

29. The method according to claim 19 wherein the generating of the first signal comprises generating a first signal by a first square wave generator for generating a first signal at a first frequency.

30. The method according to claim 19 wherein the first signal comprises a sinusoidal waveform such as a SinBOC (1,1) signal precursor or predecessor for formation of the of the SinBOC(1,1) signal.

31. The method according to claim 19 wherein the correlating comprises correlating the digital composite signal to the locally generated signal to demodulate a pilot code or navigation data encoded in the received composite signal.

32. The method according to claim 19 wherein the correlating comprises correlating the digital composite signal to the locally generated signal to identify edge transitions for tracking the carrier phase of the of the received composite signal.

33. The method according to claim 19 wherein the received composite signal comprises a multiplexed binary offset carrier (MBOC) signal, where a first portion of the received composite signal comprises a first binary offset carrier (BOC) (n,m) signal component, where a second portion of the received composite signal comprises a second binary offset carrier (BOC) (o,p) signal component, where n, m, o and p are integer values, and where the locally generated reference signal is associated with a modified BOC (n,m) signal component that is temporally dominant in a majority of the time slots of the MBOC signal, the modified BOC signal component having null codes inserted in certain time slots associated with the second BOC signal component.

34. The method according to claim 19 further comprising:

programming the controller to restrict or limit the receiver to operation in the first mode for a time period.