RETURN-WAVE, PHASE CONTROLLED ADAPTIVE ARRAY

• US 3,764,213 A
• Filed: 05/08/1972
• Issued: 10/09/1973
• Est. Priority Date: 05/08/1972
• Status: Expired due to Term

• Current Assignee: Thomas R O'Meara
• Original Assignee: Thomas R O'Meara
• Inventors: O'Meara, Thomas R.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/251,487
• Time in Patent Office: 519 Days
• Field of Search: 250/199,201,204 350/162SF 332/7.51 356/4,5
• US Class Current: 356/5.1
• CPC Class Codes: G01S 17/02 Systems using the reflection of electromagnetic waves other than radio waves G01S17/66 takes precedence
• CPC Class Codes: G01S 7/483 Details of pulse systems
• CPC Class Codes: H04B 10/1121 One-way transmission

Abstract

In accordance with one embodiment of the invention received energy from selected subapertures of an energy transmission and reception system is spatial modulated with respect to an image plane stop structure so as to produce at the output of a detector disposed behind an aperture of the image plane stop structure, modulation components indicative of the relative phase relationship associated with each subaperture receiving path. The modulation components are applied to control variable phase shifters, in common transmission and reception paths of the selected subaperture channels, in such a manner that the optical intensity of the image field transmitted through the stop structure is maximized - that is the received image is centered on the stop aperture and the image spread is reduced to the minimum. The transmitted energy, which is applied through the phase shifters adjusted with respect to the phase relationship sensed from the received signals, is thereby correctly phased to cause maximum energy to be applied to the target.

Claims

1. An energy transmission and reception system comprising:

means for transmitting energy at a target;

means for receiving a portion of the energy returned from the target;

an image plane stop structure having an aperture formed therein;

modulation means coupled in the reception path of said received energy for spatially modulating the received beam with respect to said aperture;

detector means, disposed on the opposite side of said image plane stop structure from said modulation means, for producing output signals indicative of the intensity of the received energy passing through said aperture; and

control means responsive to the output signals from said detector means, for adjusting the relative phase of selected segments of the received energy beam so as to cause the energy in the adjusted received beam to approach an in-phase condition.

2. The system of claim 1 wherein said modulation means includes means coupled in the reception path of said selected segments of the recEived beam for phase modulating, at different rates, respectively, the received energy in each of said selected beam segments, thereby producing in the output signal from said detector, modulation component signals at frequencies corresponding to the phase modulation rates of the respective segments of the received beam;

and said control means includes means for processing said modulation component signals to produce phase control signals indicative of the relative phase error of the respective selected segments of the received beam, and a plurality of electronically controllable phase shifters, with different ones of said electronically controllable phase shifters being disposed in the reception path of each of said selected segments of the received beam, and means for controlling each of said electronically controllable phase shifters in response to a different one of said phase shift control signals.

3. The system of claim 2 wherein said transmitting means includes means for transmitting pulses of energy;

and said control means including means for storing the phase control signals produced during a given reception period and for updating said stored control signals during subsequent reception periods, and means for controlling the relative phase of the energy across the transmitted beam in response to said stored phase control signals.

4. The system of claim 2 wherein said control means includes a plurality of functionally separate processing channels, with each processing channel comprising a filter series coupled to a phase sensitive detector so as to provide said phase control signal as a function of the magnitude and relative phase of one of said modulation component signals.

5. The system of claim 1 further comprising:

transmission modulation means for spatially modulating the transmission beam;

a second image plane stop structure disposed relative to said transmission modulation means for receiving a portion of the transmitted energy therefrom, said second image plane stop structure having a second aperture formed therein;

second detector means disposed on the opposite side of said second image plane stop structure from said transmission modulator means for producing output signals indicative of the intensity of the energy passing through said second aperture; and

second control means responsive to the output signals from said second detector means, for adjusting the relative phase of selected segments of the transmission beam so as to cause the energy in the adjusted transmission beam to approach an in-phase condition.

6. The system of claim 5 further comprising:

means for producing and storing transmit phase control signals indicative of the relative phase adjustments of said selected segments of the transmission beam implemented by said second control means;

first threshold means, responsive to the output signals from said second detection means, for providing an inhibit signal when the phase variations across the transmission beam are within predetermined limits; and

means, responsive to said inhibit signal for disenabling said transmission modulation means.

7. The system of claim 6 further comprising transition means for controlling, after said inhibit signal, the relative phase across the transmission beam as a function of the last stored transmit phase control signals, with said transition means including discharge-storage means for allowing the stored transmit phase control signal to decrease in accordance with a preselected program.

8. The system of claim 7 further comprising transmission defocusing means, enabled in response to said inhibit signal, for controlling the relative phase across said transmission beam such that said beam is defocussed in accordance with a preselected pattern.

9. The system of claim 8 wherein said transmission defocusing means includes a second threshold circuit, responsive to the output signals from said first detector means, for sensing when the phase across said adjusted Received beam is within preselected limits;

and logic means, responsive to the output signal from said second threshold circuit for inhibiting said transmission defocusing means.

10. The system of claim 9 further comprising beam pointing control means, enabled in response to said inhibit signal for controlling the direction of energy transmission and reception;

and second logic means responsive to the output signal from said second threshold circuit for inhibiting said beam pointing control means.

11. An energy transmission and reception system comprising:

means for transmitting energy at a target;

means for receiving a beam of energy formed from transmitted energy returned from the target;

modulation means coupled in the reception path of selected segments of the received beam for phase modulating, at different respective rates, the received energy in each of said selected beam segments;

an image plane stop structure disposed in the reception path of said beam, and having an aperture formed therein;

means for focusing the output energy from said modulation means at approximately the plane of said image plane stop structure;

detector means, disposed on the opposite side of said image plane stop structure from said modulation means, for providing output signals indicative of the intensity of the energy passing through said aperture;

a plurality of electronically controllable phase shifters with a different one of said electronically controllable phase shifters being disposed in a common transmission and reception path of each of said selected segments of the received beam; and

control means responsive to the output signals from said detector means for providing phase control signals to said plurality of electronically controllable phase shifters so as to cause the relative phase of the received energy at the output of said electronically controllable phase shifters to have an approximately plane wave front.

12. The system of claim 11 wherein said means for focusing includes a lens disposed in said reception path following said plurality of electronically controllable phase shifters;

and wherein said image plane stop structure is disposed in said reception path such that for plane wave front signals applied to said lens the output beam therefrom is approximately centered in said aperture.

13. The system of claim 12 wherein said phase modulation of the received beam causes, in the output signals from said detector means, modulation component signals at the frequencies of said modulating rates;

and said control means includes processor means responsive to said modulation component signals for respectively controlling each said electronically controllable phase shifter as a function of the modulation component signal having a frequency corresponding to the phase modulating rate of the corresponding beam segment.

14. The system of claim 13 wherein said processor means includes functionally separate processing channels for controlling said electronically controllable phase shifters, with each processing channel comprising a filter series coupled to a phase sensitive detector so as to provide a phase control signal as a function of the magnitude and relative phase of the modulation component signal having a frequency corresponding to the rate of the phase modulation applied to a given beam segment, and means for applying said phase control signal to the electronically controllable phase shifter disposed in the path of said given beam segment.

15. The system of claim 11 wherein said transmitting means includes means for transmitting pulses of energy;

and said control means including means for storing the phase control signals produced during a given reception period and for updating said stored control signals during subsequent reception periods, and means for controlling the relative phase of the energy across the transmitted beam in response to said stored phase control signals.

16. The system of claim 11 further comPrising:

transmission modulation means for spatially modulating the transmission beam;

a second image plane stop structure disposed relative to said transmission modulation means for receiving a portion of the transmitted energy therefrom, said second image plane stop structure having a second aperture formed therein;

second detector means disposed on the opposite side of said second image plane stop structure from said transmission modulator means for producing output signals indicative of the intensity of the energy passing through said second aperture; and

second control means responsive to the output signals from said second detector means, for adjusting the relative phase of selected segments of the transmission beam so as to cause the energy in the adjusted transmission beam to approach in in-phase condition.

17. The system of claim 16 further comprising:

means for producing and storing transmit phase control signals indicative of the relative phase adjustment of said selected segments of the transmission beam implemented by said second control means;

first threshold means, responsive to the output signals from said second detection means, for providing an inhibit signal when the phase variations across the transmission beam are within predetermined limits;

means, responsive to said inhibit signal for disenabling said transmission modulation means; and

transition means for controlling, after said inhibit signal, the relative phase across the transmission beam as a function of the last stored transmit phase control signals, with said transition means including discharge-storage means for allowing the stored transmit phase control signal to decrease in accordance with a preselected program.

18. The system of claim 17 further comprising transmission defocusing means, enabling in response to said inhibit signal, for controlling the relative phase across said transmission beam such that said beam is defocused in accordance with a preselected pattern.

19. The system of claim 18 wherein said transmission defocusing means includes a second threshold circuit, responsive to the output signals from said first detector means, for sensing when the phase across said adjusted received beam is within preselected limits;

and logic means, responsive to the output signal from said second threshold circuit for inhibiting said transmission defocusing means.

20. The system of claim 19 further comprising beam pointing control means, enabled in response to said inhibit signal for controlling the direction of energy transmission and reception;

and second logic means responsive to the output signal from said second threshold circuit for inhibiting said beam pointing control means.