The Ballistic Data System (BDS) has been designed as a fully integrated system which allows projectile coordinate, velocity and rate of fire measurements to be recorded automatically. In addition, the system can be used to calculate the Ballistic coefficient automatically when three Optical Detectors and the electronic scales are supplied. The data, obtained automatically or entered manually, may be used to calculate true muzzle velocities, residual energies and extreme ranges. The main benefit of the system is that all data is collected at a central point which reduces the possibility for transcription errors and speeds up measurement considerably. The pressure option consists of two additional elements to the existing Ballistic Data System: (i) A four channel 12 bit 1MHz A/D card (ii) A software module providing timing measurements and graphical display and printing. Velocity Measurement The projectile velocity is measured between the START detector and the STOP1 detector by the Velocity / rate of fire computer type 814 or Velocity / Rate of Fire interface Unit type 813. The velocity data is also sent to the Central Computer by way of the serial RS232 link.

Rate of Fire Measurement The computer type 814 or 813 measures Velocity and Rate of Fire concurrently on three channels. The pulse from the START detector is used for the Rate of Fire measurements, so no other inputs are required. The Rate of Fire data is also sent to the Central Computer by way of the serial RS232 link. Pressure Measurement The Analog to Digital card has four inputs, only two of which are normally used, namely pressure and trigger. The pressure input comes directly from the charge amplifier output and the trigger is derived from the closing contacts of the firing pin. The system is generally aimed at producing a pressure/time curve which may be displayed on screen or printed. It also calculates the integral of the curve and various time intervals. The system may also be used in 'active' mode for setup purposes and as a digital storage oscilloscope. Dispersion Measurement The shell dispersion is measured by the Large Area Optical target (LAOT). The target is connected to the Scientific Range Computer; this unit allows the target to be placed at up to 1000m from the weapon. The LAOT measures the projectile co-ordinates by the use of two orthogonal optical arrays, each array having a series of Photo-diodes. The Optical arrays have continuous d.c. light sources placed directly opposite and they detect the projectile by the shadow cast on the photo-diode. The LAOT arrays are connected to a control unit wihich provides power and calculates the X-Y coordinates from the raw signals. The coordinate data is then sent to the Scientific Range Computer by the serial link.

The Scientific Range Computer The Scientific Range Computer is an IBM PC-AT compatible machine having a hard disk and floppy disk for data storage. In addition to the control monitor, the computer may have additional remote monitors which could display the dispersion pattern, pressure data and the Velocity and Rate of Fire data. All data may be viewed on the control monitor. Ballistics Analysis Program The Ballistics Analysis Program requires the Ballistic Coefficient, C, of the projectile to be entered in order to calculate the projectile velocity at any other distance. If C is not known, the program can calculate it from two velocities measured at different points along the trajectory. This may be done by placing a third Optical Detector (STOP2) at a known distance in line and ahead of STOP1. The time intervals between START and STOP1 and STOP2 are then used to provide the two velocities. The software allows the remaining velocity and kinetic energy of the projectile to be calculated at any selected distance. To assist with the calculation of C, there is a serial connection between a set of electronic scales and the Scientific Range Computer; this allows the mass of the projectile to be recorded automatically.