Complete radio navigation receiver, particularly of the GPS type

• US 6,175,725 B1
• Filed: 10/02/1998
• Issued: 01/16/2001
• Est. Priority Date: 10/02/1997
• Status: Expired due to Fees

• Current Assignee: Dassault Electronique
• Original Assignee: Dassault Electronique
• Inventors: Auber, Jean-Claude
• Primary Examiner(s): Tsang, Fan
• Assistant Examiner(s): Ferguson, Keith
• Application Number:
  US09/165,407
• Time in Patent Office: 837 Days
• Field of Search: 342/357.06, 342/357.01, 342/357.04, 342/357.05, 455/456, 455/422, 455/457, 455/67.1, 455/67.6, 455/12.1, 455/130, 455/427, 340/988, 375/130, 375/347, 375/142
• US Class Current: 455/130
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 2201/70715 with application-specific features
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker

Abstract

A receiver of modulated carrier-wave signals equipped with a pseudo-random code time marker, particularly for radio navigation, comprises coincidence modules each of which comprises chronometric memory media which receives a wanted signal, provides storage as data of the time offset of the code offset estimates and the frequency and phase carrier-wave status, and on that basis provides, with a local clock, a local carrier-wave image and that least one local code repeat for the relevant signal and code and carrier-wave slaving control functions providing correlation of the wanted signal and the local code repeat on the basis of a frequency and phase offset signal between the carrier-wave of the wanted signal and the carrier-wave image. It further comprises Fourier transformation media for reception of the offset signal and management/decision-making media which provide invalidation of time offset data where the Fourier transformation indicates the presence of energy outside of the vicinity of a central coincidence line.

Claims

1. A device for reception of radio-electrical signals comprising a modulated carrier-wave, and equipped with a repetitive time marker, of the pseudo-random code type, with particular reference to radio-navigation, where the device comprises high-frequency reception, which produces a wanted signal with several coincidence modules, each of which is allocated to a time offset in relation to a selected respective radioelectrical signal, and means for analysis of the time offset data supplied by these coincidence modules, and wherein each coincidence module comprises:

chronometric memory media suitable for storage in the form of time offset data of a code offset estimate and a frequency carrier-wave status and phase estimate, and the corresponding deduction, with a local clock, of a local carrier-wave image and at least one local repeat of the code for the relevant radioelectrical signal, and

code and carrier-wave slaving functions operating by correlation between the wanted signal and the local code repeat, and also by means of a frequency and phase offset signal between the carrier-wave present in the wanted signal and the said carrier-wave image for purposes of bringing about coincidence between the local code repeat and the received code,

wherein said device comprises Fourier transformation media receiving the carrier-wave frequency and phase offset signal and decision-making media which are capable of invalidating, at least partially, the time offset data where the Fourier transformation indicates the presence of energy outside of the vicinity of a central line corresponding to coincidence, which provides an indication of the presence of multiple paths.

2. The device of claim 1 wherein the decision-making media are managed for purposes of validation of carrier-wave frequency and phase estimates, where the energy level obtained within a safety band adjacent to the central line, where that line is excluded, remains less than a reference level.

3. The device of claim 2, wherein the decision-making media are managed for purposes of validation of the code offset estimate where the level of energy obtained within the bands lateral to the safety band remains less than a reference level.

4. The device of claim 2 wherein the decision-making media are managed for purposes of invalidation at least of the carrier-wave phase estimate, where the level of energy obtained in the said safety margin, to the exclusion of the central line, exceeds the reference level.

5. The device of claim 4, wherein the decision-making media are managed for purposes, furthermore, of invalidating the carrier-wave frequency estimate and the code offset estimate, where the energy level obtained in the safety band exceeds a second reference level which is greater than the first.

6. The device of claim 4 wherein the decision-making media are managed for purposes of validation of the carrier-wave frequency estimate where the energy level obtained in the safety band does not exceed the second referenced levels, subject to the condition of satisfactory operation of the carrier-wave slaving loop.

7. The device of claim 2, wherein the decision-making media are managed for purposes of validation of the code offset estimate, where overshoots over the said threshold within safety margin fulfil the predetermined conditions relating to at least one of the following properties:

continuity, centring and non-overshoot of the second threshold.

8. The device of claim 1, wherein the media constituting the chronometric memory comprise a carrier-wave oscillator for definition of the carrier-wave local image, a code oscillator and a generator with at least one local code repeat.

9. The device of claim 1, wherein the code and carrier-wave slave control functions comprise:

a discrete correlation channel, comprising de-modulation according to the said carrier-wave image, and supplying a coincidence signal between the time position of the code in the wanted signal and its code encryption estimate,

at least one differential correlation channel, comprising de-modulation in accordance with the said carrier-wave image, and supplying an offset signal between the time position of the code in the wanted signal and its code encryption estimate,

the coincidence signal providing the offset variable for a phase-lock carrier-wave loop which provides pilot control of the generator of the carrier-wave local image, and

the code deviation signal providing the offset variable for a delay-locked code loop whose output is combined with that of the phase-lock carrier-wave loop for purposes of pilot control of the code repeats generator.

10. The device of claim 9, wherein decision-making media are managed to set up a further indication of the presence of multiple paths by recourse to the offset signal originating from at least one differential correlation channel.

11. The device of claim 10 wherein the coincidence module comprises at least one second differential correlation channel, and that decision-making media are managed in order to set up a further indication of the presence of multiple paths by recourse to the offset signal originating from this second differential correlation channel.

12. The device of claim 11 wherein the second differential correlation channel possesses the same centre as the first.

13. The device of claim 11 wherein the second correlation channel has a different spacing from that of the first.

14. The device of claim 13 wherein the first differential correlation channel has a spacing of less than one code step and the second differential correlation channel possesses a spacing greater than that of the first.

15. The device of claim 14 wherein the spacing of the first differential correlation channel is of the order of one tenth of a code step whilst the spacing of the second differential correlation channel is of the order of one code step.

16. The device of claim 11 wherein the spacings between the first and the second differential correlation channels are programmable.

17. The device of claim 11 wherein decision-making media are managed for purposes of establishing the other indication of the presence of multiple path on the basis of comparison between the offset signal originating from the second differential correlation channel and the offset signal originating from the first differential correlation channel.

18. The device of claim 17 wherein decision-making media are managed for purposes of establishing the other indication of the presence of multiple paths on the basis of the fact that difference between the offset signal originating from the second differential correlation channel and the offset signal originating from the first differential correlation channel exceeds another selected threshold.

19. The device of claim 17 wherein the said other indication of the presence of multiple paths established on the basis of difference takes account of the centring of frequency tracking as indicated by frequency analysis.

20. The device of claim 10 wherein decision-making media are managed for purposes of establishing the said other indication or indications of the presence of multiple paths where the offset signal originating from the differential correlation channel under consideration exceeds a selected threshold.