Velocity computing chronograph

Claim 1

A projectile velocity measuring and computing system having front and rear projectile sensing screens having outputs indicative of the passage of a projectile therethrough the apparatus comprising: a first oscillator; a chain of BCD counter stages; means responsive to the outputs of said screens for coupling said oscillator for clocking said chain of counters only during the time of flight of said projectile from the front to the rear screen means; a group of BCD coded numerical switches for manual entry of the distance between said pair of screens; an electronic digital display; a digital calculator integrated circuit having data input terminal means for serially receiving BCD digit signals, a divide command input terminal, an equals command input terminal and output means for driving said electronic digital display with the result of computation in said calculator means; means responsive to the output of said rear screen including a second oscillator and a binary counter for deriving a series of binary coded sequential numerical control signals after the flight of said projectile between said front and rear screen means; multiplexer means fed by BCD digit output signals from said BCD counter stages and numerical switches and feeding said data input terminal means of said calculator means for selectively applying different ones of said BCD digit output signals to said data input terminal means in response to the digital state of said numerical control signals, said multiplexer means being organized for serially applying first said BCD digit signals from said numerical switches and then from said BCD counter stages in response to the sequential numerical control signals, there being at least one predetermined numerical control signal state between the application of said BCD digit signals from said BCD coded numerical switches and from said BCD counter stages; means responsive to said predetermined control signal state for driving said divide command input terminal; and means responsive to the occurrence of a last of said numerical control signals for driving said equals command input terminal.