Identification friend or foe discriminator

• US 5,355,241 A
• Filed: 08/02/1993
• Issued: 10/11/1994
• Est. Priority Date: 12/09/1991
• Status: Expired due to Fees

• Current Assignee: Kelley, Clifford W.
• Original Assignee: Kelley, Clifford W.
• Inventors: Kelley, Clifford W.
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): BACARES, RAFAEL D
• Application Number:
  US08/100,299
• Time in Patent Office: 435 Days
• Field of Search: 359/152, 359/154, 359/155, 359/169, 359/170, 350/4, 350/28, 342/45, 342/53, 342/54
• US Class Current: 398/170
• CPC Class Codes: G01S 17/74 Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 7/48 of systems according to group G01S17/00
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence

Abstract

An IFF device comprises a beam generator for directing an unmodulated beam at a target. The target has a plurality of retro-reflectors mounted on it. These retro-reflectors have internal reflecting surfaces for reflecting the unmodulated beam penetrating the retro-reflector. A device is associated with the internal reflecting surfaces for modulating the beam at a predetermined frequency so that the reflected beam emerging from the retro-reflector is modulated at the same frequency. A tuner is positioned in the path of the reflected modulated beam and tuned to predetermined frequency, so that if the tuner receives a signal, it indicates the target is friendly.

Claims

1. An IFF device comprising a beam generating means for directing a beam at a target, at least one retro-reflecting device adapted to be mounted on a target, each retro-reflecting device having internal reflecting surfaces shaped so an unmodulated beam striking the reflecting device penetrates said retro-reflecting device and strikes the internal reflecting surfaces, means associated with said internal reflecting surfaces for modulating said beam inside said retroreflector by changing its intensity at the internal surfaces of the retroreflector at a predetermined frequency whereby the modulated beam is reflected back out of the retro-reflecting device in a direction parallel to and back toward the beam generating means, a tuner, said tuner positioned in the path of the modulated reflected beam and having means for adjusting the tuner to the predetermined frequency of the reflected beam whereby if the tuner receives the modulated signal from the reflected beam it indicates the target is friendly.

2. An IFF device comprising a beam generating means for directing a beam at a target, at least one retro-reflecting device adapted to be mounted on a target, each retro-reflecting device having internal reflecting surfaces shaped so an unmodulated beam striking the reflecting device penetrates said retro-reflecting device and strikes the internal reflecting surfaces, means associated with said internal reflecting surfaces for modulating said beam inside said retro-reflecting device by changing its intensity at a predetermined frequency whereby the modulated beam is reflected back out of the retro-reflecting device in a direction parallel to and back toward the beam generating means, said means comprising a layer of elastomeric material positioned close to one of said internal reflecting surfaces in said reflecting device and separated therefrom by a gap, a piezoelectric strip secured to the surface of the elastomeric material remote from surface facing the said internal reflecting surface, whereby when alternating voltage is applied to said piezoelectric strip the dimensions of the elastomeric material and the width of said gap change in accordance with the frequency of alternating voltage causing the width of said gap to vary at the same frequency, thereby causing changes in the intensity of the reflected beam to occur at the same frequency as the frequency of the alternating voltage, a tuner, said tuner positioned in the path of the modulated reflected beam and having means for adjusting the tuner to the predetermined frequency of the reflected beam whereby if the tuner receives the modulated signal from the reflected beam it indicates the target is friendly.

3. An IFF device comprising a beam generator for directing a beam at a target, at least one trihedral retro-reflector adapted to be mounted on a target, said trihedral retro-reflector having internal reflecting surfaces shaped so an unmodulated beam striking the trihedral retro-reflector penetrates said trihedral retro-reflector and strikes said internal reflecting surfaces, means associated with said internal reflecting surfaces for modulating said beam inside said retroreflector by changing its intensity at the internal surfaces of the retroreflector at a predetermined frequency, whereby the modulated beam is reflected out of said trihedral retro-reflector in a direction back toward the beam generator, and a tuner, said tuner positioned in the path of said reflected modulated laser beam and having means for adjusting the tuner to the frequency of the reflected modulated beam, whereby if the tuner receives the signal from the reflected intensity modulated beam, the target is friendly.

4. An IFF discriminator comprising a beam generating means for directing a beam at a target, at least one retro-reflecting device adapted to be mounted on the target, each retro-reflecting device having internal reflecting surfaces shaped so an unmodulated beam penetrating said retro-reflector strikes the internal reflecting surfaces, means external to one of said internal reflecting surface for modulating the internal reflected beam inside the retro-reflector by changing its intensity at the internal surfaces of the retroreflector at a predetermined frequency, whereby the modulated beam is reflected back out of the retro-reflector in a direction parallel to and back toward the beam generating means, a tuner, said tuner positioned in the path of the modulated reflected beam and having means for adjusting the frequency to the selected frequency controlled by the said external means, whereby if the tuner received the modulated signal from the reflected beam, it indicates the target is friendly.

5. An IFF device having a beam generating device for directing a beam at a target, at least one retro-reflecting device adapted to be mounted on a target, each retro-reflecting device formed from material having an index of refraction greater than air and having internal reflecting surfaces arranged so a beam striking the retro-reflecting devices penetrates said retro-reflecting device and strikes the internal reflecting surfaces, a material having an index of refraction close to the index of refraction of the retro-reflector positioned close to an internal reflecting surface defining an air gap, means for moving said material toward and away from the said internal reflecting surface at a predetermined frequency, causing said air gap to change in size so that when the said beam absorbing material moves away from said internal reflecting surface said material frustrates the intensity of the reflected beam as the size of the air gap increases, whereby the frequency of the change in the intensity of the reflected beam varies at the same frequency as the said predetermined frequency, a tuner, said tuner positioned in the path of modulated reflected beam, means for tuning said tuner to the frequency of the modulated reflected beam, whereby if the tuner receives the modulated signal the target is friendly.

6. An IFF device comprising a beam generating means for directing a beam at a target, at least one retro-reflecting device adapted to be mounted on a target, each retro-reflecting device having internal reflecting surfaces shaped so an unmodulated beam striking the reflecting device penetrates said retro-reflecting device and strikes the internal reflecting surfaces, a layer of elastomeric material positioned close to one of said internal reflecting surfaces in said reflecting device and separated therefrom by an air gap, means for causing said elastomeric material to vibrate at a predetermined frequency whereby the dimensions of the elastomeric material vary in accordance with the frequency of alternating voltage causing the width of said air gap to vary the same way thereby causing changes in the intensity of the reflected beam to occur inside the retro-reflecting device at the internal surfaces of the retroreflector at the same frequency as the said predetermined frequency, a tuner, said tuner positioned in the path of the modulated reflected beam and having means for adjusting the tuner to the predetermined frequency of the reflected beam whereby if the tuner receives the modulated signal from the reflected beam it indicates the target is friendly.