Adaptive zero mean system for controlling noise false alarm rate

A false alarm control system responsive to a source of radar log video signals representative of the presence or absence of radar targets from a plurality of radar sweeps each having T range bins comprising:

• accumulating means for integrating said radar video signals to provide an accumulated value,
• count pulse forming means coupled to said source of log video signals for providing count pulses;
• counting means coupled to said count pulse forming means for counting said count pulses;
• comparison means coupled to said counting means for providing a reset pulse to said counting means and a shift pulse to said accumulating means after T radar log video signals are counted;
• storage means coupled to said accumulating means and responsive to said shift pulses for storing the mean value of the accumulated log video signals scaled as a function of T;
• and
• subtracting means responsive to said log video signals and to said stored mean value for providing a zero mean signal.

A constant mean false alarm control system responsive to log video signals from a plurality of range bins along a radar range transmission sweep during a selected live time comprising:

• first comparison means responsive to said log video signal for forming a count signal when said video signal is above a threshold;
• counter means responsive to said count signal;
• accumulator means responsive to said log video signal and said count signal for accumulating said video signal in response to said count signals;
• storage means coupled to said accumulator means;
• a source of a reference value equal to the number of range bins per range sweep;
• second comparison means coupled to said counter means and to said source of a reference value for determining when the count is equal to said reference value and coupled to said counter means, accumulator means and storage means for resetting said counter means and for transferring a mean value to said storage means;
• and
• subtractor means coupled to said storage means and responsive to said log video signals for providing a constant mean output signal.