Beam focused synthetic aperture

• US 4,067,009 A
• Filed: 08/01/1975
• Issued: 01/03/1978
• Est. Priority Date: 08/01/1975
• Status: Expired due to Term

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: James Nickolas Constant
• Inventors: Constant, James Nickolas
• Primary Examiner(s): Tubbesing, T.H.
• Application Number:
  US05/601,392
• Time in Patent Office: 886 Days
• Field of Search: 343/5 CM
• US Class Current: 342/25.00A
• CPC Class Codes: G01S 13/4409 HF sub-systems particularly adapted therefor, e.g. circuits for signal combination multi-lobing aerials or aerial systems H01Q25/00
• CPC Class Codes: G01S 13/9005 with optical processing of the SAR signals

Abstract

A beam focused synthetic aperture having a lens or antenna for receiving radiation in a receiving beam from an object of interest, a detector for receiving radiation from the lens or antenna, and an output and display circuit for using and viewing the detector output, with delay means internal or external to the lens or antenna and between the object and detector and for producing the matched spatial filtering of signals from objects crossing the receiving beam, and with the detector producing a pulse for each object crossing the receiving beam.

Claims

1. In a synthetic aperture having first means for forming a beam for receiving radiation from a target, a detector for a radiation beam from said first means, and an output and display for using and viewing detected signals from the detector, the improvement comprising:

a delay means inserted between the target and the detector, said delay means including a spatial matched filter for said radiation from said target moving through the field of view of said radiation beam.

2. A synthetic aperture as defined in claim 1 including a transmitter for directing radiation to said target in said receiving beam.

3. A synthetic aperture as defined in claim 1 including a local oscillator for heterodyning signals in said detector.

4. A synthetic aperture as defined in claim 1 including a beamsplitter-recombiner in combination with said delay means.

5. A synthetic aperture as defined in claim 4 wherein said beamsplitter-recombiner includes means for splitting incoming radiation from said target into at least two beams along different paths, and means for recombining the outgoing radiation into a single beam, with the paths of different length providing a differential time delay in one separated beam relative to the other.

6. A synthetic aperture as defined in claim 4 wherein said beamsplitter-recombiner includes a beamsplitter and beam combiner with said beamsplitter directing an incoming beam along a first and along a second path to at least one mirror for reflection to said recombiner for recombining to form an outgoing beam along the first path.

7. The system of claim 4 wherein the beamsplitter includes at least one mirror and means for directing an incoming beam along a first path and along a second path to at least one mirror for reflection to the recombiner for recombining to form an outgoing beam along the first path.

8. A synthetic aperture as defined in claim 1 wherein said delay means includes a delay unit which provides said spatial matched filter and a beamsplitter-recombiner means which provides a cosine modulation of a beam passing through said delay means.

9. A synthetic aperture as defined in claim 1 in a system for identifying objects with a coded label, wherein said target crossing said receiving beam is a label attached to an object, and with a plurality of labels with a label for each object.

10. A system as defined in claim 9 wherein said label is a harmonic means.

11. A system as defined in claim 9 wherein the code of said coded label is a binary code.

12. A system as defined in claim 9 with

each of said labels having a plurality of code element locations with code elements disposed at selected locations, with the presence and absence of code elements at code element locations comprising a code for the object, and with a code element comprising a zone having a radiation characteristic different from that of the background.

13. A system as defined in claim 12 wherein the spacing of code element locations of a label for a system operating at a particular wavelength and frequency is substantially proportional to the size of said lens or antenna along the path of relative motion of said synthetic aperture and label. pg,52

14. A system as defined in claim 12 wherein the spacing of code element locations of a label is substantially a linear dependence of the antenna size along the path of relative motion of said synthetic aperture and label and is substantially independent of wavelength and range.

15. A system as defined in claim 9 wherein said label is a non-harmonic means.

16. A system as defined in claim 9 wherein the code of said coded labels is a bar code.

17. A synthetic aperture as defined in claim 1 wherein said radiation from a target is an electromagnetic radiation.

18. A system as defined in claim 1 wherein said delay means is inserted in a location internal to said first means.

19. A system as defined in claim 1 wherein said delay means is inserted in a location external to said first means.

20. The system of claim 1 wherein said spatial matched filter is a non-dispersive delay line.

21. A synthetic aperture as defined in claim 1 wherein said radiation from a target is an acoustic radiation.

22. The system of claim 1 wherein said spatial matched filter is a dispersive delay line.

30. The method of claim 1 including the step of varying one of the frequency-time characteristics of said matched filter and differential time delay of said beamsplitter-recombiner.

23. A method of generating a synthetic aperture, comprising the steps of:

generating an electromagnetic receiving beam;

receiving unsynchronized spatial signals from targets crossing said receiving beam;

synchronizing said unsynchronized signals in a spatial matched filter prior to their being detected; and

detecting said synchronized spatial signals as impulsive electrical currents.

24. A method as defined in claim 23 including the step of:

generating a transmitting beam for illuminating targets for reflecting signals to said receiving beam.

25. A method as defined in claim 23 including the step of:

generating a local oscillator signal for heterodyning signals in said detector.

26. A method as defined in claim 23 including the step of:

controlling the frequency-time characteristic of said matched filter.

27. A method as defined in claim 23 including the steps of:

providing labels in the form of coded targets; and

attaching labels to objects for identifying objects with a code.

28. A method as defined in claim 23 including the step of cosine modulating signals.

29. The method of claim 23 including the step of cosine modulating said unsynchronized signals prior to their being detected.