System and method for obtaining precise missile range information for semiactive missile systems

A system for determining the distance between a missile and a target comprising:

• first means for generating a periodic signal, said periodic signal having a first component of a first constant frequency and a second component of a second varying frequency;
• second means for determining a closing rate at which said missile is approaching said target from said first component;
• and
• third means for determining a value containing information corresponding to said distance between said missile and said target and said closing rate via said second component;
• and
• fourth means for determining said distance from said closing rate and said value.

A method for determining the distance between a missile and a target comprising the steps of:

• generating a periodic signal frequency modulated at a predetermined rate;
• measuring a closing rate at which said missile is approaching said periodic signal;
• determining a value containing information corresponding to said distance between said missile and said target and said closing rate via said periodic signal;
• and
• calculating said distance from said closing rate and said value.

A semi-active missile system capable of accurately determining the distance between a missile and a target comprising:

• an illumination source for outputting a first periodically modulated carrier signal;
• a receiver system located on said missile and having a front and rear receiver for receiving a reflected periodically modulated carrier signal, and said first periodically modulated carrier signal, respectively;
• a first software routine running on a computer, said first software routine for calculating a missile target closing rate from a non-modulated portion of said first periodically modulated carrier signal, and a non-modulated portion of said reflected periodically modulated carrier signal received by said receiver system;
• a second software routine running on said computer, said second software routine for obtaining a value representative of a combination of missile target closing rate and said distance from a modulated portions of said first periodically modulated carrier signal and said reflected periodically modulated carrier signal received by said receiver system;
• a third routine running on said computer for extracting said distance from said value using said missile target closing rate;
• a missile propulsion system;
• a missile steering system;
• a guidance processor for controlling said missile propulsion system and said missile steering system to guide said missile, said guidance processor utilizing said distance to optimize missile performance;
• and
• an intercept arm function for using said distance to selectively activate the arming of said missile in response to said distance being within a predetermined distance threshold.