RADIO COMMUNICATION SYSTEM

• US 3,774,209 A
• Filed: 11/18/1970
• Issued: 11/20/1973
• Est. Priority Date: 02/25/1970
• Status: Expired due to Term

• Current Assignee: Clarence A. Lovell, James Evans Fleming, James M. Bandle
• Original Assignee: Clarence A. Lovell, James Evans Fleming, James M. Bandle
• Inventors: Lovell, Clarence A., Fleming, James Evans, Bandle, James M.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/090,598
• Time in Patent Office: 1,098 Days
• Field of Search: 343/102,105
• US Class Current: 342/386
• CPC Class Codes: G01S 1/302 Systems in which the direction is determined by using an interferometric type transmitting antenna array
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236

Abstract

A novel radio communication system is disclosed, the system having particular applicability and utility as a radio navigation aid. A transmitting means is utilized which, in the preferred inventive embodiment, comprises a plurality or array of antennas disposed in fixed spaced-apart relationship with one another at a known location. One of the transmitting antennas transmits a reference signal, preferably a carrier wave, modulated by a first frequency or frequencies. The remaining transmitting antennas each transmits a single or double sideband suppressed carrier signal produced by respectively different modulating frequencies for each signal. These different modulating frequencies bear a harmonic or multiple relationship with the first modulating frequency or frequencies. In the preferred inventive embodiment, each of the remaining transmitting antennas are disposed at different distances from the first or reference transmitting antenna. The novel system further includes receiver and signal processing means disposed either at the same or different locations remote from the location of the transmitting means. The receiver means generates from the received reference signal a signal having the frequency and phase of the first modulating signal at the transmitter. From this signal, the other modulating signals coherent with the first signal are derived. The receiver/signal processing means derives from the other received signals the second, third, and fourth modulating signals, and compares the phases of the signals of like frequency. In an alternative embodiment wherein the receiver means and signal processing means are disposed at different remote locations, and each receives the signals transmitted by the transmitting array, the receiver means serves only to detect the various modulating frequencies, and then retransmits the detected frequencies to the signal processing means for phase comparison. In each instance, the detected phase differences are indicative of the relative angular direction of the receiver means from the transmitting array. In the preferred embodiment, the antennas of the transmitting array are disposed on a line and the phase difference detected represents the angular deviation of the receiver from a plane bisecting and perpendicular to the line of transmitting antennas. The accuracy of the system is determined by the maximum spacing between a pair of antennas in the array. The other antennas are used only for resolving ambiguities.

Claims

1. A radio communication system comprising a transmitting antenna array defining a plurality of spaced-apart antennas, transmission means coupled to said antenna array such that one antenna transmits a reference frequency signal, and such that each other antenna transmits a signal having respectively different frequency characteristics than said reference frequency signal;

remote receiver-transmitter means for receiving the composite transmitted signals and for retransmitting at least some of said signals without relative phase shift therebetween, a signal processor means disposed at a remote location with respect to said antenna array for receiving said retransmitted signals from said receiver-transmitter means and said composite signals transmitted from said antenna array, said signal processor means including comparator means for comparing the phase of said received signals from the receiver-transmitter means with the phase of received signals of like frequency characteristics from the transmitting antenna array and for generating an output therefrom indicative of the locus of the positions of said receiver-transmitter means with respect to the location of said transmitting antenna array.

2. A radio communication system as defined in claim 1 wherein said remote receiver-transmitter means retransmits said signals from a single antenna and at a different carrier frequency than the carrier frequency of said signals transmitted from said antenna array.

3. A radio communication system comprising a plurality of transmitting antenna means, one of said antenna means transmitting a reference signal comprising a carrier and a plurality of single sidebands having a given frequency difference therebetween, each of the other antenna means transmitting a suppressed carrier signal having a respectively different single sideband modulating frequency component, receiver system means for said transmitted signals disposed at a remote location, said receiver means having radio antenna means and including means for detecting said reference signal and said frequency difference between the sidebands thereof and for synthesizing each of said respectively different modulating frequency components therefrom, said receiver system means further including comparator means for selectively comparing the phase of said synthesized signals with the phase of the transmitted sIgnals, said receiver system means generating an output from the compared phase differentials representative of the locus of the receiver antenna positions with respect to said plurality of antenna means.

4. A system as defined in claim 3, wherein said comparator means of said receiver multiplies said first signal by a given multiple to produce a third signal having the same frequency as the frequency of said second signal, and compares the phase of said third signal with the phase of said second signal to generate said output.

5. A system as defined in claim 4, including additional spaced-apart transmitting antennas, each transmitting a wave comprising respectively different modulating signals, each said different modulating signal comprising a frequency having a different multiple of said first modulating frequency, said comparator means of said receiver selectively multiplying said first signal by each said different multiple to respectively produce a plurality of third signals each having the same frequency as the frequency of a respective different modulating signal, each said third signal being phase-compared with the phase of said respective different modulating signal to generate said output.

6. A system as defined in claim 5, wherein said reference wave comprises an amplitude modulated carrier and wherein said other transmitted waves comprise suppressed carrier single sideband amplitude modulated signals.

7. A system as defined in claim 5, wherein said second and each said additional transmitting antenna is disposed at different distances from said first transmitting antenna, said distances bearing the same respective relationship with one another as the relationship between the different multiples of the transmitted modulating frequencies.

8. A system as defined in claim 4, wherein said reference wave comprises an amplitude modulated carrier and wherein said wave transmitted by said second antenna comprises an amplitude modulated suppressed carrier having a double sideband, said comparator means of said receiver internally regenerating said suppressed carrier from the received double sidebands, said regenerated carrier comprising said third signal, and wherein said comparator means compares the phase of said regenerated carrier with the phase of said transmitted carrier of said reference wave to produce said output.

9. A radio communication system as defined in claim 5, wherein said reference wave comprises an amplitude modulated carrier and wherein said other transmitted waves comprise amplitude modulated suppressed carriers having double sidebands, said comparator means of said receiver internally regenerating the suppressed carriers from the received double sidebands, said regenerated carriers comprising said third signals, and wherein said comparator means compares the phase of each said regenerated carrier with the phase of said transmitted carrier of said first signal to produce said output.

10. A radio communication system as defined in claim 5, wherein the output of said receiver means indicates the angular deviation of the location of said receiver antenna from a plane bisecting and perpendicular to a line between two of said transmitting antennas.

11. A radio communication system as defined in claim 5, further including calibration means associated with said transmission means, such that said first transmitting antenna selectively and simultaneously transmits all of said signals, the other transmitting antennas being inoperative.

12. A radio communication system as defined in claim 3, wherein each of said other antenna means transmits a suppressed carrier double sideband signal.

13. A radio communication system as defined in claim 3, wherein each of said other antenna means transmits a suppressed carrier single sideband signal.

14. A radio communication system comprising:

a transmitter means including first antenna means for generating and transmitting a first signal having a first frequency component, and additional Spaced antenna means for generating and transmitting other signals having respectively different frequency components each being a multiple of said first frequency component; and

a receiver system including means for receiving said transmitted signals, means for synthesizing from said first signal additional signals having frequency components that are the same as said other transmitted signals, and means for comparing the phases of said synthesized signals respectively with the phases of said other transmitted signals having the same frequency to provide an output representative of the position of the receiving means relative to the transmitter means.

15. A radio communication system as defined in claim 14, wherein said first signal comprises an amplitude modulated carrier and wherein said other signals comprise single sideband amplitude modulated suppressed carriers.

16. A radio communication system as defined in claim 14, wherein said first signal comprises an amplitude modulated carrier and wherein said other signals comprise double sideband amplitude modulated suppressed carriers and wherein said means for synthesizing serves to synthesize carrier signals having the same phase angle as would said suppressed carriers, had said suppressed carriers been transmitted.

17. A radio communication system comprising:

an antenna array including at least two antennas, means for generating a first signal comprising a carrier modulated by a first signal frequency to be transmitted over a first antenna, means for generating other signals by modulating the carrier by signals of other frequencies, each of said signals to be transmitted over a different antenna and a receiver system including means for receiving said transmitted signals, said receiver system further including means for deriving from the received composite signal each of the modulating signals, means for synthesizing from the first modulating signal, signals having respectively the frequencies of each of other said modulating signals, phase comparison means for comparing the phase of the derived modulating signal of like frequency, and means for deriving from said phase comparisons the angular position of said receiving means with respect to lines joining the pairs of transmitting antennas.

18. A radio communication system as defined in claim 17, wherein the first signal comprises an amplitude modulated carrier and wherein said other signals comprise single sideband amplitude modulated carrier signals with carriers suppressed.

19. A radio communication system as defined in claim 17, wherein the first signal comprises an amplitude modulated carrier and wherein said other signals comprise double sideband amplitude modulated carrier signals with carriers suppressed, and wherein said means for synthesizing serves to synthesize carrier signals having respectively the same phase angles at the receiver as would said suppressed carriers had said suppressed carriers been transmitted.

20. A radio communication system as defined in claim 17, wherein first said signal comprises a carrier, and single sidebands from each of two modulating frequencies, and wherein each other transmitted signal is a single sideband amplitude modulated signal with carrier suppressed and wherein each of the other modulating frequencies is a multiple of the difference of the two frequencies modulating the carrier to produce first said signal.

21. A radio communication system as defined in claim 17, wherein said signal synthesizing, phase comparing and angular position determining means of the receiver system are separated from the receiving means, and connected to said receiving means by a radio link, whereby the derived modulation signals are transmitted from the receiving means to the location of the other said means without relative phase shift among said derived modulation signals.

22. A radio communication system as defined in claim 18, wherein said signal synthesizing, phase comparing and angular position determining means of the receiver system are separated from the receiving means, and connected to said receiving means by a radio link, whereby the derived modulation signals are transmitted from the receiving means to the location of other said means without relative phase shift among said derived modulation signals.

23. A radio communication system as defined in claim 19, wherein said signal synthesizing, phase comparing and angular position determining means of the receiver system are separated from the receiving means, and connected to said receiving means by a radio link, whereby the derived modulation signals are transmitted from the receiving means to the location of other said means without relative phase shift among said derived modulation signals.

24. A radio communication system as defined in claim 14, wherein said signals synthesizing and phase comparison means of the receiver system are physically separated from the receiving means and are operationally connected thereto by means of a radio link.