Radio navigation system and apparatus

• US 3,928,852 A
• Filed: 10/25/1973
• Issued: 12/23/1975
• Est. Priority Date: 10/25/1973
• Status: Expired due to Term

• Current Assignee: Sp-Marine Incorporated
• Original Assignee: Barker A. Clifford
• Inventors: Barker, A. Clifford
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Montone, G. E.
• Application Number:
  US05/409,363
• Time in Patent Office: 789 Days
• Field of Search: 343/15R,15H,15LS,13R,112R,112TC
• US Class Current: 342/396
• CPC Class Codes: G01S 1/30 the synchronised signals being continuous waves or intermittent trains of continuous waves, the intermittency not being for the purpose of determining direction or position line and the transit times being compared by measuring the phase difference

Abstract

A high-resolution compatible coastal confluence radio navigation system includes two local stations cooperable with a distant station of an Omega network or the like. The local stations, which are spaced by a distance substantially less than the usual long distance between Omega stations, transmit audio tone signals modulated on a high frequency carrier and directly or indirectly phase-locked to a signal received from the distant station. The phase relationships of the audio tones and a signal from the distant station are employed in a novel mobile receiver for deriving position information. Novel local station apparatus is also disclosed.

Claims

1. A high-resolution local radio navigation system employing a remote VLF transmitting station, said system comprising first and second local stations which are spaced from each other by a distance which is substantially less than the distance between said remote station and either one of said local stations so as to provide a short base line between said local stations and a substantially longer base line between said first local station and said remote station, said first and second local stations including means for transmitting, at higher frequency than VLF frequencies, first and second local signals, respectively, which are each phase-locked to a VLF signal transmitted by said remote station, said first local signal being cooperable with said VLF signal to produce a first family of equi-phase lines corresponding to said first local station and said remote station and further being cooperable with said second local signal to produce a second family of equiphase lines corresponding to said first and second local stations, and a mobile receiver having means for comparing the phase of said first local signal with the phases of said second local signal and said VLF signal to provide an indication of the position of the receiver in relation to said families of equi-phase lines.

2. A radio navigation system as set forth in claim 1, wherein one of said local stations includes means responsive to said VLF signal for generating the associated one of said local signals.

3. A radio navigation system as set forth in claim 2, wherein said means for generating said one signal comprises frequency-changing means for generating said one local signal with a frequency different from the frequency of said VLF signal.

4. A radio navigation system as set forth in claim 3, wherein said frequency-changing means comprises a frequency divider for generating said first local signal in the form of an audio tone.

5. A radio navigation system as set forth in claim 2, wherein said means for transmitting said one local signal includes means for modulating a carrier wave with said one local signal.

6. A radio navigation system as set forth in claim 2, wherein said one local station is keyed ON periodically during predetermined time slots and is keyed OFF at all other times.

7. A radio navigation system as set forth in claim 2, wherein the other local station includes means responsive to said one local signal for generating the other local signal.

8. A radio navigation system as set forth in claim 7, wherein said means for transmitting said other local signal includes means for modulating a carrier wave with said other local signal.

9. A radio navigation system as set forth in claim 7, wherein said other local station is keyed ON periodically during predetermined time slots and is keyed OFF at all other times.

10. A radio navigation system as set forth in claim 7, wherein said means responsive to said one local signal comprises frequency-changing means for generating said other local signal with a frequency different from the frequency of said one local signal.

11. A radio navigation system as set forth in claim 1, wherein said other local signal is an audio tone.

12. A radio navigation system as set forth in claim 1, wherein said first and second local stations are spaced along a common shoreline.

13. A radio navigation system as set forth in claim 1, employing one of the transmitting stations of the Omega radio navigation network as said remote station, and wherein said VLF signal comprises an Omega signal transmitted by said one transmitting station.

14. A radio navigation system as set forth in claim 1, wherein said first and second local stations are positioned so as to make said short base line substantially perpendicular to said longer base line.

15. A radio navigation system as set forth in claim 1, wherein said means for transmitting said first and second local signals at higher frequency than VLF frequencies comprises means for modulating a carrier wave with said local signals.

16. A radio navigation system as set forth in claim 1, further comprising a third local station spaced apart from said first and second local stations, said third local station including means for transmitting, at higher frequency than VLF frequencies, a third local signal which is phase-locked to said VLF signal, said third local signal being cooperable with one of said first and second local signals to produce a third family of equi-phase lines corresponding to said third local station and said one local station, whereby a mobile receiver having means for comparing the phases of said local signals can provide an indication of the position of the receiver with reference said second and third families of equi-phase lines.

17. A radio navigation system as set forth in claim 16, wherein said means for transmitting said first, second and third local signals at higher frequency than VLF frequencies comprises means for modulating a carrier wave with said local signals.

18. A mobile receiver for use in a local radio navigation system employing a remote VLF transmitting station and first and second local stations, said local stations being spaced from each other by a distance substantially less than the distance between said remote station and either one of said local stations so as to provide a short base line between said local stations and a substantially longer base line between said first local station and said remote station, and transmitting, at higher frequency than VLF frequencies, first and second local signals, respectively, which are each phase-locked to a VLF signal transmitted by said remote station, said first local signal being cooperable with said VLF signal to produce a first family of equi-phase lines corresponding to said first local station and said remote station and further being cooperable with saiD second local signal to produce a second family of equiphase lines corresponding to said first and second local stations, said receiver comprising:

means for receiving said VLF signal;

means for receiving said first and second local signals; and

means for comparing the phase of said first local signal with the phase of said VLF signal to provide an indication of the position of the receiver relative to said first family of lines and for comparing the phase of said first local signal with the phase of said second local signal to provide an indication of the position of the receiver relative to said second family of lines.

19. A radio navigation receiver as set forth in claim 18 for use in a radionavigation system employing one of the transmitting stations of the Omega radio navigation network as said remote station, wherein said means for receiving said VLF signal comprises means for receiving an Omega signal transmitted by said one transmitting station.

20. A radio navigation receiver as set forth in claim 18, wherein the frequency of said local signals is different from that of the VLF signal, and further comprising means for changing the frequency of said local signals to the frequency of said VLF signal.

21. A radio navigation receiver as set forth in claim 18, wherein said local signals are transmitted as modulations of a carrier wave, and wherein said means for receiving said local signals includes means responsive to said modulated carrier wave for detecting said local signals.

22. A high-resolution local radionavigation system employing one Omega transmitting station of an Omega network, said system comprising first and second local stations which are spaced from each other by distance which is substantially less than the distance between the stations of the Omega network, said first and second local stations including means for transmitting, at higher frequency than Omega frequencies, first and second local signals, respectively, which are phase-locked to an Omega signal transmitted by said one Omega station, said first local signal being cooperable with said second local signal to produce a family of equi-phase lines corresponding to said first and second local stations, and a mobile receiver having means for comparing the phase of said first local signal with the phase of said second local signal to provide an indication of the line of position of the receiver in relation to said family of equi-phase lines.

23. A mobile receiver for use in a local radionavigation system employing one Omega transmitting station of an Omega network and first and second local stations, said local stations being spaced from each other by a distance substantially less than the distance between the stations of the Omega network and transmitting, at higher frequency than Omega frequencies, first and second local signals, respectively, which are each phase-locked to an Omega signal transmitted by said one Omega station, said first local signal being cooperable with said second local signal to produce a family of equi-phase lines corresponding to said first and second local stations, said receiver comprising:

means for receiving said first and second local signals; and

means for comparing the phase of said first local signal with the phase of said second local signal to provide an indication of the line of position of the receiver relative to said family of lines.

24. A local station for a high-precision local radionavigation system for use with one station of an Omega network, said local station comprising means for receiving an Omega signal transmitted only by said one Omega station;

means for generating a continuous further signal that is phase-locked to said received Omega signal;

frequency divider means responsive only to said further signal for dividing the frequency of said further signal and for generating an audio tone, the phase of which varies as a sub-multiple of the phasE of the Omega signal; and

means for transmitting a carrier wave modulated with said audio tone.

25. A local station as set forth in claim 24, further comprising means automatically stabilizing the phase of said transmitting means.