SYSTEM 86 ACOUSTIC TARGET

Acoustic Target Introduction

Oehler acoustic targets have been in use since 1982. Advances in available computation power, along with improved microphones, have allowed significant improvements over the years.

Newest Oehler acoustic targets (System 86) offers many advantages for testing direct-fire weapons and ammunition. These advantages include:

• Proven accuracy better than 0.2% of target size. This accuracy has been demonstrated in actual firing tests under field conditions.
  
  
• Targets up to 10 meters square are used routinely. Larger targets can be provided.
  
  
• Demonstrated high reliability. Systems have been in operation for many years.
  
  
• Wireless system with a range of over 10 kilometers from target to operator. This allows easy installation even in rough or contaminated terrain.
  
  
• Each set of target coordinates is time-stamped to an accuracy of a few microseconds using GPS time. This time-stamping allows data to be interpreted using proven exterior ballistic models.
  
  
• No prior knowledge of projectile velocity, projectile arrival angle, or wind is required.
  
  
• The downrange portion of the system requires only 12-volt dc power at approximately 1 amp.
  
  
• Software automatically finds and rejects abnormal signals from microphones. One noisy microphone or random signals during a burst will not prevent proper system function.
  
  
• Software provides a measure of quality or confidence on each shot to prevent acceptance of invalid scoring.
  
  
• The system is currently being certified using redundant acoustic targets along the projectile path and matching with physical target and proven exterior ballistics model.

General Description

The Oehler System 86 Acoustic Target consists of sixteen sensors (microphones) distributed around or adjacent to the target. Each sensor responds to the leading edge of the Mach cone associated with a passing projectile. The time of arrival of the Mach cone at each sensor is recorded with microsecond resolution by the System 86 Controller and is transmitted to the control room computer. These arrival times are subsequently processed to provide apparent hit location along with the computed arrival time at the apparent target plane.

The control room computer is dedicated to one gun, but can simultaneously manage up to 10 System 86 Controllers. One controller is used at the gun to provide muzzle mark time to the system and one controller is required for each downrange acoustic target. Multiple targets (up to nine) can be used for one gun in either slow fire or burst fire tests.

The computation algorithm has been proven with several years of field tests. Use of sixteen sensors provides redundancy by which two microphones can be automatically excluded from the computations if their arrival times are not consistent with other arrival times for the shot. The computation also includes display of a residual time to provide a positive indication of system malfunction on any shot.

Communication between the control room computer and the downrange controllers is via radio. These radio links have a maximum range of well over 10 km with line-of-sight and proper antennae.

Each target controller includes a GPS receiver and a stable time-of-day clock slaved to the received GPS timing signals. Thus all recorded times are absolutely referenced to the same base. This allows the output from multiple acoustic target systems to be used with proven exterior ballistics models to provide a precise measurement of muzzle velocity. Note that the precise measure of muzzle velocity requires a muzzle exit signal and at least three downrange targets distributed along the flight path.

Contact Oehler for pricing and availability.