Multiple screen ballistic chronograph

• US 4,845,690 A
• Filed: 04/04/1988
• Issued: 07/04/1989
• Est. Priority Date: 04/04/1988
• Status: Expired due to Term

• Current Assignee: Kenneth L. Oehler
• Original Assignee: Kenneth L. Oehler
• Inventors: Oehler, Kenneth L
• Primary Examiner(s): Miska, Vit W.
• Application Number:
  US07/177,098
• Time in Patent Office: 456 Days
• Field of Search: 368/1, 368/6, 368/9, 368/10, 368/113-118, 364/565, 364/569, 273/371-372
• US Class Current: 368/113
• CPC Class Codes: G04F 10/00 Apparatus for measuring unknown time intervals by electric means

Abstract

A chronograph system includes three shot-sensing screens which provide start and stop signals to interval-determining timers. The first screen provides a start signal to both timers and the subsequent screens provide stop signals to the first and second timers, respectively. The time intervals measured by these timers are divided into the distances between the screens to separately calculate two velocities based on two different distances. The calculated velocities are compared to evaluate the performance of the instrumentation so that measurement errors resulting from the instrumentation itself can be eliminated from analysis of the test shots.

Claims

1. An apparatus for measuring the velocity of a projectile and for indicating the possibility of an instrument-generated measuring error comprising the combination of

a plurality of more than two projectile sensors each including means for sensing the passage of a projectile through a monitored plane and for producing a substantially real-time pulse signal indicating that a projectile has passed;

means for supporting said sensors with their respective monitored planes occupying a predetermined spaced relationship along a linear path to be traversed by a projectile so that the projectile can pass through the planes associated with all three sensors and normally be sensed by each said sensor;

first timing circuit means connected to receive the pulse signal outputs of a first pair of said sensors for determining the first elapsed time between the pulse signals and dividing said predetermined spacing between the planes monitored by said first pair of sensors by said first elapsed time to provide a first velocity calculation, and for providing an output representative of said first velocity calculation;

second timing circuit means connected to receive the pulse signal outputs of a second, different pair of said sensors for determining a second elapsed time between said pulse signals and dividing said predetermined spacing between the planes monitored by said second pair of sensors by said second elapsed time to provide a second velocity calculation and for providing an output representative of said second velocity calculation;

means for displaying said first and second velocity calculations; and

means for comparing said first and second velocity calculations and for providing an "alert" indication when said velocity calculations differ from each other by a predetermined amount.

2. An apparatus according to claim 1, wherein one of the sensors in each of said first and second pairs is the first sensor reached by said projectile.

3. An apparatus according to claim 1 wherein the number of sensors is three.

4. A method for measuring the velocity of a projectile and for indicating the possibility of a measuring error comprising the combination of

supporting a plurality of more than two projectile sensors so that their respective monitored planes occupy a predetermined spaced relationship along a linear path to be traversed by a projectile and so that the projectile can pass through the planes associated with all of the sensors and normally be sensed by each of the sensors, each sensor including means for sensing the passage of a projectile through a monitored plane and for producing a substantially real-time pulse signal indicating that a projectile has passed;

combining the pulse signal outputs of a first pair of the sensors for determining the first elapsed time between the pulse signals, dividing the predetermined spacing between the planes monitored by the first pair of sensors by the first elapsed time to provide a first velocity calculation and providing an output representative of the first velocity calculation;

combining the pulse signal outputs of a second, different pair of the sensors for determining a second elapsed time between the pulse signals, dividing the predetermined spacing between the planes monitored by the second pair of sensors by the second elapsed time to provide a second velocity calculation, and providing an output representative of the second velocity calculation;

displaying the first and second velocity calculations;

comparing first and second velocity calculations, and providing an "alert" indication when the velocity calculations differ from each other by a predetermined amount.