CODED NAVIGATION SYSTEM

• US 3,818,478 A
• Filed: 08/14/1972
• Issued: 06/18/1974
• Est. Priority Date: 08/14/1972
• Status: Expired due to Term

• Current Assignee: Herbert L. Groginsky
• Original Assignee: Herbert L. Groginsky
• Inventors: Groginsky, Herbert L.
• Primary Examiner(s): Farley, Richard A.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/280,320
• Time in Patent Office: 673 Days
• Field of Search: 343/18M,16R 235/150.26
• US Class Current: 342/398
• CPC Class Codes: G01S 1/02 using radio waves G01S19/00 takes precedence

Abstract

In a navigation system in which a beam of radiation is utilized for communicating information to a vehicle, such as an aircraft approaching a landing strip, there is provided a pseudo-noise generated binary code having sequentially generated bits ordered in a sequence of nonrepeating subsequences with each of these bits uniquely representing a value of a coordinate describing the position of the beam of radiation. For example, with an azimuthally scanned beam of radiation, each bit in the code represents an increment in the azimuth angle while the digits of one of the subsequences is sufficient to uniquely determine the azimuth angle. An encoder and a decoder, each similarly structured with a shift register and feedback logic, are disclosed.

Claims

1. A system comprising in combination:

means for modulating a beam of radiant energy with information relative to the position of said beam, said modulating means including means for encoding said information with a sequence of binary signals, said sequence comprising a plurality of nonrepetitive subsequences of binary signals, each of said binary signals being associated with a position of said beam;

means spaced apart from said beam modulating means for demodulating said nonrepetitive subsequences of binary signals;

means coupled to said demodulating means for predicting the next binary signal of said sequence; and

means coupled to said predicting means for counting the number of said predictions for extracting said information to determine said position.

2. The system according to claim 1 wherein said modulating means further comprises means synchronized with said beam position for transmitting a timing signal towards said demodulating means.

3. A navigation system comprising in combination:

means for modulating a beam of radiant energy with information relative to the position of said beam, said modulating means including means for encoding said information with a sequence of binary signals, said sequence comprising a plurality of non-repetitive subsequences of binary signals, each of said binary signals being associated with a position of said beam;

means, responsive to said radiant energy and carried by a vehicle illuminated with said radiant energy for extracting said information to determine the position of said beam, said modulating means further comprising means synchronized with said beam position for transmitting a timing signal towards said vehicle, said timing signal and said binary signals being modulated on a carrier of said radiant energy, and wherein said extracting means comprises;

means for demodulating said timing signal and said binary signals from said carrier; and

means responsive to said binary signals for predicting the next binary signal of said sequence in synchronism with said timing signal.

4. The system according to claim 3 wherein said encoding means comprises:

a shift register;

a logic means connected to selected parallel outputs of said shift register, said logic means providing a binary one signal when an odd number of binary one signals appear on said parallel outputs, said logic means providing a binary zero signal when an even number of binary one signals appear on said selected parallel outputs;

means for initializing the binary signals of said shift register; and

means for inserting the outputs of said logic means into said shift register.

5. The system according to claim 4 wherein said extracting means comprises means coupled to said predicting means for counting the number of said predictiOns;

and means responsive to said counting means for inhibiting the passage of further ones of said binary signals to said predicting means when a preset number of said predictions has proved correct.

6. The system according to claim 5 wherein said predicting means comprises:

a data register having means for shifting binary signals in a first direction;

a logic means being connected to selected parallel outputs of said register, said logic means providing a logic one signal when an odd number of said selected register outputs have a value of one, said logic means providing a logic zero signal when an even number of said selected register outputs have a value of logic one; and

a coincidence detector coupled to said logic means and to said demodulating means for providing a signal to said prediction counting means whenever a signal provided by said logic means equals the next signal from said demodulating means, said signal provided by said coincidence detector indicating the correctness of each of said predictions.

7. A system according to claim 6 wherein said extracting means further comprises:

a source of threshold signal;

a detector of the amplitude of received radiant energy; and

means for comparing said amplitude of received radiant energy with said threshold signal, said comparing means providing a signal during an interval of time in which said vehicle is illuminated by said radiant energy.

8. The system according to claim 7 wherein said predicting means is enabled by said time interval signal of said comparator.

9. The system according to claim 5 wherein said extracting means comprises means, coupled to said demodulating means and to said counting means, for decoding a sequence of said binary signals, said decoding means comprising:

a data register having means for shifting binary signals in a first direction and in a second direction, said register being initially loaded with a sequence of said binary signals by shifting said binary signals in said first direction;

a logic means being connected to selected parallel outputs of said register, said logic means providing a logic one signal when an odd number of said selected register outputs have a logic value of one, said logic means providing a logic zero signal when an even number of said selected register outputs have a logic value of one, the output signals of said logic means being coupled to an input of said register;

a source of clock signals for shifting said output signals of said logic means in said register in said second direction;

means coupled to said outputs of said register for detecting the presence of a predetermined set of output signals, said detecting means being coupled to said source of clock signals for impeding said clock signals when said predetermined set of outputs is present at said data register; and

means for counting the clock signals of said source of clock signals during said shifting of data in said register in said second direction, the count of said clock counting means representing the position of said beam.