Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1980-08-08
2002-03-19
Buczinski, Stephen C (Department: 3662)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C089S041070, C250S342000, C250S50400H, C244S003130, C244S003160
Reexamination Certificate
active
06359710
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to countermeasures against infrared (IR) radiation-seeking devices and especially to a pulse system and method for jamming IR-seeking reticle-type missiles.
Present operational U.S. IR missile jammers rely on prior knowledge of threat-missile operating characteristics and, in fact, normally operate at frequencies close to those of threat-missile gyro spin rates. Previous IR countermeasures designed to defeat IR-guided missiles which use reticles for encoding target information utilize three general techniques: deception, disruption and damage. Deception and disruption generally occur at irradiance levels a few orders of magnitude greater than the seekers noise equivalent temperature (NET). This level may vary from 10
−11
to 10
−8
watts/cm
2
for most reticle-type seekers. Present jammers operate at jammer-to-target (J/S) signal levels of from 2 to 8, typically. Some jammers use electrically modulated, alkali-metal-seeded, rare-gas arc sources while some employ fuel-fired or electrically heated grey-body sources which are mechanically modulated by one or more rotating and/or slotted discs, slats or cylinders. The primary method of deception jamming employed these devices relies on the creation of false signals in the missile seekers electronic processing system, especially in the inner gyro tracking loop of spin-scan missiles. After amplification, this false or deceptive signal causes the gyro to precess in a direction looking away from the true target. The result when the target passes out of the gyro-telescope's field-of-view is called “optical break lock”.
These jammers are also sometimes effective against conical-scan seekers but for somewhat different reasons. In con-scan seekers, the maximum disruption of the inner gyro tracking loop is usually no more than a wobble superimposed on the correct motion of the gyro as it follows the target. With deception jamming specially chosen frequencies pass into the seeker's airframe guidance section which is disrupted by non-linearities, dither, or target-signal suppression. The end result for these con-scan seekers is that, although the gyro tracks, the canard wing deflections are either insufficient or too distorted to fly the missile to its target.
The primary disadvantage of present IR jammer systems is that their effectiveness depends on having prior information about the critical gyro spin frequencies of the threat missiles to be countered. Unfortunately, little is known about the internal functions of any but the oldest operational IR missiles in the inventories of various nations. There are additional difficulties, such as the spectral output and inflexibility of modulation schemes of current U.S. IR jammers.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to reduce the dependence of jam-format effectiveness against IR-seeker missiles on prior knowledge of threat-missile characteristics.
The objects and advantages of the present invention are accomplished by employing a pulse jamming system against IR-seeking missiles, in which the pulse-train characteristics, especially the pulse spacings, are randomized.
REFERENCES:
patent: 3427611 (1969-02-01), Enenstein
patent: 3514776 (1970-05-01), Mulready
patent: 3720944 (1973-03-01), Kramer et al.
patent: 3771731 (1973-11-01), Dyner
patent: 3797395 (1974-03-01), Tyroler
patent: 3878525 (1975-04-01), Alpers
patent: 3900875 (1975-08-01), Scheets
patent: 3942179 (1976-03-01), Dorn
patent: 3978342 (1976-08-01), Hagen et al.
patent: 4112300 (1978-09-01), Hall, Jr. et al.
Goodell William V.
Pasko Joseph E.
Takken Edward H.
Buczinski Stephen C
Karacek John J.
McDonnell Thomas E.
The United States of America as represented by the Secretary of
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