Education and demonstration – Organized armed or unarmed conflict or shooting – Aerial warfare
Reexamination Certificate
2001-04-20
2003-12-30
Cheng, Joe H. (Department: 3713)
Education and demonstration
Organized armed or unarmed conflict or shooting
Aerial warfare
C434S019000, C273S372000, C073S167000, C367S127000
Reexamination Certificate
active
06669477
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates generally to a computer-implemented process and apparatus for scoring supersonic aerial projectiles, and more particularly to a time-difference process and apparatus for measuring the acoustic shock waves propagated by supersonic aerial projectiles to calculate the impact points of the projectiles on a strafe target. Also determined are projectile dive angle, projectile approach heading, projectile velocity and other useful scoring data such as the number and rate of projectiles fired, the impact pattern of the projectiles, projectile caliber, and estimated strafing distance of the strafe aircraft.
This invention is directed to a time-difference process and apparatus for scoring supersonic aerial (strafe) projectiles fired at a strafe target. The process and apparatus scores each projectile by measuring, detecting and calculating the differences of the time of arrival of the acoustic shock wave propagated by the projectile at an array of transducers disposed nearby the strafe target.
The process of past scoring systems has been to sample acoustic shock waves of supersonic aerial projectiles by use of a single or pairs of acoustic transducers. These transducer(s) produce an electrical signal whose amplitude is a function of the projectile distance from the transducer and the projectile size and speed. This signal is sent to a computer-implemented scoring unit where it is scaled using fixed projectile caliber and signal threshold parameters. The scaled signal is then compared to a preset threshold level. If the signal is greater than the threshold the scoring unit assumes that the projectile passed through the strafe target and a score (e.g., a “hit”) is registered. If the signal is lower than the threshold level, no score (e.g., a “miss” is registered.
The accuracies of the past scoring processes are dependent on the amplitude of the signal generated by the transducer. Any factor that adversely affects this amplitude of measuring acoustic shock waves produces inaccurate strafing scores. For instance, the use of fixed projectile caliber and signal threshold parameters produces scoring errors because projectiles have varying muzzle velocity and ballistic parameters based upon the manufacturer type and production date of the projectiles. Moreover, since commercial transducers do not have identical frequency responses, transducers matched at one frequency or projectile caliber will not match at different calibers. Transducers also degrade due to weathering and must have regular calibration performed to insure accuracy. Such calibration is typically time-consuming and expensive.
Past scoring processes do not adequately account for the adverse affect on scoring accuracy caused by the speed of the strafing aircraft or platform firing the supersonic aerial projectiles. The speed of a strafing aircraft affects the velocity of the projectile at the target, which in turn affects the amplitude of the signal produced by the transducer. Aircraft strafing at high speeds will produce greater scores than would be received at slower speeds due to the increased energy of the shock wave at the target location. Past scoring processes do not differentiate between aerial (strafe) projectiles fired from static or slow-moving platforms and projectiles fired from fast-moving platforms such as jet aircraft, even though this has a significant affect on scoring accuracy.
Moreover, in past scoring processes the firing range of a strafing aircraft must be known to accurately set the fixed projectile-caliber parameter. In field use, however, strafing aircraft firing ranges vary widely between different aircraft, different pilots of the same aircraft, and even different strafing passes of the same pilot. Scoring inaccuracies results because aircraft strafing at close range receive greater scores than would be received at farther ranges due to the increased energy of the acoustic shock wave at the strafe target.
Past scoring processes also do not adequately account for the affect of ambient weather conditions on the flight paths of the aerial projectiles and upon the acoustic shock waves propagated by the projectiles. For example, the acoustic transducers used in some prior scoring apparatus use a thermistor in their circuitry that is intended to, but does not adequately compensate for, the changes in the transducer electrical output signal caused by varying ambient atmospheric temperatures. Varying ambient atmospheric temperature, wind velocities and barometric pressures significantly affect the energy of the shock wave and flight characteristics of the aerial projectiles. These weather conditions can in turn have an adverse affect on scoring accuracy because the transducer amplitude produced can vary under identical strafing parameters. The degree to which weather conditions adversely affect system accuracy is unknown in the past scoring processes and no calculation to compensate for weather affects is used.
Past scoring processes do not indicate to an operator what region of the strafe target the aerial projectiles impacted, in what order they arrived at the strafe target for pattern analysis, or which direction the off-target projectiles went. Moreover, using past processes it is very difficult for the pilot of the strafe aircraft to accurately assess aerial projectile scoring patterns due to the typically-extreme firing distances involved and the necessity for strafing aircraft bank away from the target after firing. Spotting planes and video-based surveillance systems are sometimes used to spot such scoring patterns, but not to any degree of useful accuracy. Since the impact pattern of the aerial projectiles cannot be accurately determined using the past scoring processes, analysis of aircraft pilot technique, strafe projectiles and strafe-gun system performance, and weather (notably wind velocity) affects are not possible.
Past scoring processes are inaccurate because they use a scoring area defined by the polar detection pattern of the transducer rather than the strafe target itself. In past scoring processes, the scoring area is semi-elliptical or can be made semi-circular with the addition of a transducer “cap.” This non-tactical shape is essentially defined by the polar pattern of the transducer's microphone and cannot be changed. The scoring area position is fixed by the location of the transducer and cannot be offset from it. Since the physical range target is often offset from the transducer, this offset can produce scoring errors because the strafe target can be impacted without the scoring process indicating any corresponding score.
Past scoring processes also lack printout or storage capabilities for scoring archival purposes and trend analysis. Finally, aerial projectile parameters such as the projectile dive angle, strafe aircraft firing range, and the heading angle cannot be determined by the past scoring processes.
Information relevant to attempts to address these problems can be found in:
a. U.S. Pat. No. 4,813,877 to Sanctuary, et al.
Further relevant attempts to address these problems can be found in the following printed publications:
b. EON Instrumentation, Inc., Operational and Maintenance Manual for the Remote Strafe Scoring System Model SSS-101 (1989);
c. YPG/Oehler Research, Field Acoustic Target for Yuma Proving Ground (1998);
d. Air Target Sweden AB, Miss Detection Calculator MDC-80 (1986);
e. Acoustic Detection Traces Bullet, Shell Trajectories, Signal Magazine (November 1994);
f. Building a Better Bullet, Air Force Magazine (July 1993);
g. Sniper Locator Finds Shooter Quickly, National Defense Magazine (November 1996);
h. Arcata Associates, Inc., ARCATA/ADI Air-to-Ground Scoring System—System Test Report (1995);
i. Oehler Research, Inc., Enhanced Acoustic Scoring System—Informal Report (1995); and
j. Cartwright Electronics, Executive Summary CEI-2728 Area Weapons Scoring System (1990).
Each one of these references, h
Lopes, Esq. Crane L.
The United States of America as represented by the Secretary of
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