HETERODYNE AUTOCORRELATION GUIDANCE SYSTEM

• US 3,836,951 A
• Filed: 05/05/1960
• Issued: 09/17/1974
• Est. Priority Date: 05/05/1960
• Status: Expired due to Term

• Current Assignee: Claude C. Routh, Keith E. Geren, Milton D. Papineau
• Original Assignee: Claude C. Routh, Keith E. Geren, Milton D. Papineau
• Inventors: Geren, Keith E., Papineau, Milton D., Routh, Claude C.
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US04/020,225
• Time in Patent Office: 5,248 Days
• Field of Search: 340/6,16,3 343/113,100.7,16.1,16 114/23
• US Class Current: 367/125
• CPC Class Codes: F41G 7/228 using acoustic waves, e.g. for torpedoes
• CPC Class Codes: G01S 3/8083 determining direction of source

Abstract

1. In a guidance system adapted to sense incoming energy and ascertain the direction thereof comprising in combination a first means for receiving incoming radiant energy and producing a first electrical output signal proportional thereto, a second means for receiving incoming radiant energy and producing a second electrical output signal proportional thereto, means coupled to said first and second receiving means for accepting the electrical output signals therefrom and transforming same into a sum signal representing the addition thereof and a difference signal representing the subtraction thereof, means connected to said transforming means for receiving said sum signal and said difference signal and for converting same into a pair of electrical signals having identical fixed frequencies and a phase relationship in accordance with the relative left and right direction of said incoming energy, means connected to said sum and difference signal converting means for comparing the phase relationship between said identical fixed frequency signals and producing an output signal in accordance therewith, and readout means coupled to said relative phase comparing means for indicating said relative phase relationship in terms of said relative left and right direction of said incoming energy.

Claims

1. In a guidance system adapted to sense incoming energy and ascertain the direction thereof comprising in combination a first means for receiving incoming radiant energy and producing a first electrical output signal proportional thereto, a second means for receiving incoming radiant energy and producing a second electrical output signal proportional thereto, means coupled to said first and second receiving means for accepting the electrical output signals therefrom and transforming same into a sum signal representing the addition thereof and a difference signal representing the subtraction thereof, means connected to said transforming means for receiving said sum signal and said difference signal and for converting same into a pair of electrical signals having identical fixed frequencies and a phase relationship in accordance with the relative left and right direction of said incoming energy, means connected to said sum and difference signal converting means for comparing the phase relationship between said identical fixed frequency signals and producing an output signal in accordance therewith, and readout means coupled to said relative phase comparing means for indicating said relative phase relationship in terms of said relative left and right direction of said incoming energy.

2. A heterodyne autocorrelation guidance system comprising in combination a first hydrophone, a second hydrophone, a sum-difference transformer network connected to the outputs of said hydrophones for producing a sum signal output and a difference signal output, a sum heterodyne correlation channel coupled to said sum-difference transformer network for producing a first output signal at a fixed frequency that is independent of the sum signal input frequency, a difference heterodyne correlation channel coupled to said sum-difference transformer network for producing a second output signal having a frequency identical with said first fixed frequency output signal and independent of the difference signal input frequency, means connected to said sum and difference heterodyne correlation channels for delaying a portion of said sum signal output and feeding same thereto for deletion of random noise signals from the aforesaid first and second fixed frequency output signals, means connected to said sum and difference heterodyne correlation channels for regulating the frequency of the aforesaid first and second fixed frequency output signals therefrom, a phase detector connected to the outputs of said sum and difference heterodyne correlation channels for response to said first and second fixed frequency output signals, and readout and control means coupled to the output of said phase detector.

3. Means for determining the bearing of acoustical energy received from a source comprising in combination a pair of transducers, means connected to the outputs of said transducers for converting same into sum signals and difference signals, first and second bandpass filters connected to said converting means for response to said sum and difference signals respectively, a sum signal channel coupled to the output of said first bandpass filter, a difFerence signal channel coupled to the output of said second bandpass filter, a local oscillator effectively connected between said sum and difference channels, a delay line interconnecting the output of said first bandpass filter and the aforesaid sum and difference signal channels, means connected to the outputs of said sum and difference signal channels for correlating the relative phase therebetween, and means coupled to the output of said correlating means for indicating and recording the output therefrom in terms of the aforesaid acoustical energy source bearing.

4. The means of claim 3 wherein said pair of transducers include hydrophones adapted to produce electrical signals upon excitation by received acoustical energy while being submerged in an aqueous medium.

5. The means of claim 3 wherein said first and second bandpass filters include means for establishing the band acceptance thereof between five and thirty kilocycles per second.

6. The means of claim 3 wherein said delay line is a lumped constant low-pass LC network with a delay time of 660 microseconds.

7. The means of claim 3 wherein said means connected to the outputs of said sum and difference signal channels for correlating the relative phase therebetween is a phase detector which delivers a signal having a DC voltage component, the polarity and potential of which depends on the relative phase of the input signals.

8. The means of claim 3 wherein said sum and difference signal channels are substantially identical and include a first ring modulator, a bandpass filter connected to the output of said first ring modulator, a second ring modulator coupled to the output of said bandpass filter, and a tuned filter connected to the output of said second ring modulator.

9. The means of claim 8 wherein the bandpass filter connected to the output of said first ring modulator is an upper side band filter having a bandpass of forty-seven to seventy-two kilocycles per second.

10. The means of claim 8 wherein said tuned filter is a lower side band filter having a pass frequency equal to the forty-two kilocycles per second output frequency of said local oscillator.

11. A twin heterodyne autocorrelation guidance system comprising in combination a first transducer, a second transducer spacially disposed from said first transducer, means coupled to the outputs of said first and second transducers for simultaneous producing sum signals and difference signals, a sum correlator channel connected to receive said sum signals, a difference correlator channel connected to receive said difference signals, means connected to said sum and difference correlator channels for heterodyning said sum and difference signals into a pair of output signals having fixed identical frequencies and variable relative phase relationships, means connected to the outputs of said sum and difference channels for measuring the phase difference between said fixed identical frequency signals and producing an output signal proportional thereto, and readout and control means coupled to said phase measuring means for response to the aforesaid proportional signal.

12. A heterodyne autocorrelation passive sonar guidance system adapted for determining the bearing of sonic energy received under water and guiding a carrier vehicle in accordance therewith comprising in combination a pair of hydrophones adapted to convert acoustical energy into proportional electrical signals, means connected to said hydrophones for transforming the electrical signals therefrom into a pair of signals one of which represents the sum thereof and the other of which represents the difference thereof, means for filtering said sum and difference signals to provide outputs within identical predetermined frequency ranges, means for heterodyning said filtered sum and difference signals with a given frequency signal, means connected to said heterodyning means for passing the upper sidebands of said heterodyned sum and difference signals, means for heterodynIng said upper sidebands of each of said sum and difference signals with a delayed version of the sum signals from said first mentioned filtering means, means coupled to the outputs of said last mentioned heterodyning means for passing the lower sidebands produced thereby, means interconnecting said last mentioned passing means for correlating said lower sideband and determining the relative phase therebetween, and means coupled to the output of said correlating means for indicating said relative phase relationship and controlling the attitude of said carrier vehicle in accordance with a predetermined navigational path pertinent thereto.

13. A heterodyne autocorrelation navigation system comprising in combination a plurality of transducers, a sum-difference transducer network coupled to said transducers for converting the outputs therefrom to sum and difference signals, a first bandpass filter connected to said sum-difference transformer network for response to said sum signals, a first ring modulator connected to the output of said first bandpass filter, a second bandpass filter connected to the output of said first ring modulator, a second ring modulator coupled to the output of said second bandpass filter, a tuned filter connected to the output of said second ring modulator, a third bandpass filter connected to said sum-difference transformer network for response to the difference signal therefrom, a third ring modulator coupled to the output of said third bandpass filter, a fourth bandpass filter connected to the output of said third ring modulator, a fourth ring modulator coupled to the output said fourth bandpass filter, a second tuned filter connected to the output of said fourth ring modulator, a local oscillator, first and second phase shifters interconnecting said local oscillator and said first and third ring modulators respectively, a delay line connected between the output of said first bandpass filter and said second and fourth ring modulators, a phase detector interconnecting the outputs of said first and second tuned filters, and readout and control means coupled to the output of the aforesaid phase detector.

14. A method of determining and recording the relative left and right bearing of acoustical energy received within an aqueous medium comprising the steps of sensing said acoustical energy at two remotely disposed stations, converting said sensed acoustical energy into a pair of electrical signals, mixing said pair of electrical signals to produce signals representing the sum and difference thereof, filtering said sum and difference signals to predetermined ranges of frequencies respectively, heterodyning said predetermined ranges of frequencies with a given frequency, passing the upper sidebands of said heterodyned frequencies, heterodyning said upper sidebands with delayed sum signals originally obtained from filtering said sum and difference signals to predetermined ranges of frequencies, passing the lower sidebands produced by said last mentioned heterodyning step, correlating said lower sidebands and the relative phase relationship therebetween, and reading out said relative phase relationship in terms of received acoustical energy bearing.

15. A heterodyne autocorrelation guidance system comprising in combination, a pair of transducers each of which is adapted for converting predetermined incoming radiant energy into electrical signals proportional thereto, means coupled to said pair of transducers for transforming said proportional electrical signals into a pair of output signals one of which is the algebraic sum thereof and the other of which is the algebraic difference thereof, means effectively coupled to said transforming means for heterodyning said sum and difference signals with a predetermined oscillating signal, a first filter means coupled to the output of said heterodyning means for passing the upper sideband of said heterodyned sum signals, a second filter means coupled to the output of said heterodyning means for passing the upPer sideband of said heterodyned difference signals, means effectively interconnecting said transforming means and said first and second filter means for simultaneously heterodyning said passed sum and difference upper sidebands with a delayed version of the aforesaid unheterodyned algebraic sum signals, filter means coupled to the outputs of said upper sideband heterodyning means for respectively passing the lower sidebands of the sum and different signal outputs therefrom as a pair of signals having a fixed frequency and a variable relative phase relationship, and means effectively connected to the outputs of said lower sideband passing filter means for detecting and reading out the relative phase of said pair of fixed frequency signals in terms of the direction of travel of the aforesaid incoming radiant energy.