| 摘要 |
A laser based range finder includes plural user selectable target acquisition and enhanced precision measurement modes which may be viewed on an in-sight display during aiming and operation of the instrument. The range finder includes a self-calibrating precision timing circuit (24) and an automatic noise threshold circuit (36). The precision timing circuit utilizes an internal central processing unit crystal oscillator (30). The automatic noise threshold circuit (36) and method automatically sets an operating threshold for a signal receiving section of a laser pulse transmitting circuit (18) such that a constant noise pulse firing rate is output from a detector (20) to provide maximum return signal sensitivity and enable detection of the weakest possible laser pulse by a pulse detector (24) and laser receiver circuit (22). The range is calculated in a central processing unit (28) and displayed on an LCD display (32).
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