NAVIGATION SATELLITE SYSTEM

• US 3,852,750 A
• Filed: 10/16/1972
• Issued: 12/03/1974
• Est. Priority Date: 10/16/1972
• Status: Expired due to Term

• Current Assignee: Perry Ian Klein
• Original Assignee: Perry Ian Klein
• Inventors: Klein, Perry Ian
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/298,138
• Time in Patent Office: 778 Days
• Field of Search: 343/15R,1ST
• US Class Current: 342/396
• CPC Class Codes: G01S 1/308 particularly adapted to Omega systems
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308

Abstract

A long range navigation system and method for determining the position of mobile vehicles using synchronous satellites. Three or more synchronous satellites alternately relay a radio frequency carrier amplitude modulated with a plurality of very low frequency tones. Each mobile vehicle is equipped with a communications receiver, including an AM detector and position location equipment. The AM - detected output of the communications receiver is connected to the position location equipment, which determines the position of the vehicle from the relative phases of the tones.

Claims

1. A method of determining the position of an object comprising:

a. transmitting in succession from each of at least three synchronous satellites an RF carrier, said carrier being modulated with at least one very low frequency (VLF) tone;

b. receiving said successive transmissions at said object;

c. demodulating said successive transmissions;

d. measuring the phase difference between tones of the same frequency transmitted from different ones of said satellites;

e. using two or more of said measured phase differences to determine the location of said object.

2. The method of claim 1 wherein said RF carrier originates from a central station and is transmitted in succession from said ground station to each of said satellites.

3. The method of claim 2 wherein said RF carrier is amplitude modulated and said ground station includes means for time delaying the modulation of said RF carrier whereby said tone is transmitted with the same phase from each synchronous satellite.

4. The method of claim 3 wherein said RF carrier is modulated with the sum of the VLF tones of 10.2 kHz, 11.33 kHz and 13.6 kHz.

5. A navigation satellite system for providing mobile objects with information that will enable a determination of their geographic position comprising:

a. at least three synchronous satellites, each including means for transmitting a radio frequency carrier, modulated with a plurality of very low frequency (VLF) tones;

b. radio frequency receiving means located at eaCh of said objects and including means for demodulating each of said radio frequency carriers to derive said plurality of VLF tones;

c. VLF receiving means connected to said radio frequency receiving means including means for measuring the phase difference between identical ones of said tones transmitted from different ones of said satellites.

6. A navigation satellite system as claimed in claim 5 wherein said VLF tones comprise the frequencies of 10.2 kHz, 11.33 kHz and 13.6 kHz.

7. A navigation satellite system as claimed in claim 6 further comprising:

a. a central station including means for transmitting a modulated radio frequency carrier at a first frequency to each satellite in sequence; and

, wherein said satellite includes means for receiving the central station carrier and for connecting said received carrier to a transmitter for transmission to the mobile object at a carrier frequency different from said first carrier frequency.

8. A navigation satellite system as claimed in claim 7 wherein said central station comprises:

a. first, second, and third very low frequency oscillators;

b. first, second, and third time delay means each corresponding to a different one of said three synchronous satellites and each receiving signals from said first, second and third very low frequency oscillators;

c. multiplexing means for sequentially sampling said first, second, and third time delay means;

d. modulator means connected to said multiplexing means for producing a radio frequency carrier amplitude modulated with the output of said multiplexing means; and

e. directional antenna means for transmitting the amplified output of said modulator means to each of said three synchronous satellites in succession.

9. A navigation satellite system as claimed in claim 8 wherein said central station further comprises:

a. synchronizing means for providng control signals to said multiplexing means and said antenna means whereby said multiplexing means connects the respective output of each of said first, second, and third time delay means to said modulator means at the same time the antenna means is transmitting to the synchronous satellite associated with that time delay means.

10. A navigation satellite system as claimed in claim 9 wherein said antenna means comprises a steerable directional antenna and antenna control means for alternately steering the antenna beam in the direction of each of said synchronous satellites in response to control signals from said synchronizing means.

11. A navigational satellite system as claimed in claim 8 wherein said first, second, and third time delay means are variable to permit compensation for relative drift in the distances between said first, second, and third synchronous satellites from said ground station.