Automatic noise threshold determining circuit and method for a laser range finder
DCFirst Claim
1. An automatic noise threshold system for operative association with central processing and signal receiving sections of a signal pulse transmitting device for discriminating between an actual return signal pulse and noise that is associated with said actual return signal pulse, said system comprising:
- determining means responsive to said central processing section for determining a desired signal-to-noise ratio for a series of said actual return signal pulses and said associated noise received through said signal receiving section, each one of said return signal pulses and associated noise having a representative pulse value with respect to a signal pulse that was previously transmitted from said signal pulse transmitting device and that corresponds thereto; and
stack-placing means responsive to said central processing section for placing up to a preselected number of said representative pulse values in a stack until a predetermined number of said representative pulse values coincide within a specified precision, wherein said predetermined number of said representative pulse values that coincide within said specific precision are considered to be representative of said actual return signal pulse.
5 Assignments
Litigations
0 Petitions
Accused Products
Abstract
An automatic noise threshold circuit and method automatically sets an operating threshold for a signal receiving section of a laser pulse transmitting device such that a constant noise pulse firing rate is output from a detector to provide maximum return signal sensitivity and enable detection of the weakest possible laser pulse in order to obtain maximum performance out of a laser range finder. The circuit sets the noise pulse rate at that point at which, in conjunction with a firmware based process, the actual return signals from the target can be discrimintated from the accompanying noise.
78 Citations
40 Claims
-
1. An automatic noise threshold system for operative association with central processing and signal receiving sections of a signal pulse transmitting device for discriminating between an actual return signal pulse and noise that is associated with said actual return signal pulse, said system comprising:
-
determining means responsive to said central processing section for determining a desired signal-to-noise ratio for a series of said actual return signal pulses and said associated noise received through said signal receiving section, each one of said return signal pulses and associated noise having a representative pulse value with respect to a signal pulse that was previously transmitted from said signal pulse transmitting device and that corresponds thereto; and stack-placing means responsive to said central processing section for placing up to a preselected number of said representative pulse values in a stack until a predetermined number of said representative pulse values coincide within a specified precision, wherein said predetermined number of said representative pulse values that coincide within said specific precision are considered to be representative of said actual return signal pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method for discriminating between an actual return-reflected signal and associated noise in a signal receiving section of a signal transmitting device, the method comprising the steps of:
-
transmitting a series of signal pulses to a target; receiving a number of reflected signal pulses from said target, said reflected signal pulses including both noise and actual return-reflected signal pulses; assigning a pulse value for each of said reflected signal pulses with respect to said series of signal pulses transmitted to said target; comparing each of said assigned pulse values with other ones of said assigned pulse values; continuing to perform said comparing step until a predetermined number of said assigned pulse values coincide within a specified precision; and determining said actual return signal to be represented by said predetermined number of said assigned pulse values. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
-
18. An automatic noise threshold circuit for use in a laser range finder, comprising:
-
a laser light receiver for generating an electrical signal in response to a received light signal, said received light signal containing both signal and noise light pulses; and a circuit for automatically adjusting a noise threshold of said laser light receiver to a level at which said laser light receiver produces an output from said noise light pulses having a constant pulse firing rate. - View Dependent Claims (19, 20, 21, 22, 23, 24)
-
-
25. A method for automatically adjusting a noise threshold in a laser range finder, comprising:
-
generating an electrical signal in response to a received light signal from a laser light receiver, said electrical signal containing signal and noise light pulses; and adjusting a noise threshold of said laser light receiver to a level at which said laser light receiver produces a noise light pulse output having a constant pulse firing rate. - View Dependent Claims (26, 27, 28)
-
-
29. A method for determining a range to a target, said range being based upon an actual-flight-time of a pulse that is directed toward said target, said method comprising the sequential steps of:
-
establishing first and second electrical reference levels; initially-unclamping said second electrical reference level; allowing said second electrical reference level to change at a first rate relative to said first electrical reference level; storing a first time period T1 that is representative of a time that expires between said step of initially-unclamping said second electrical reference level until said first and second electrical reference levels become equal; re-establishing said first and second electrical reference levels; again-unclamping said second electrical reference level; changing said second electrical reference level at a second rate that is higher than said first rate for a predetermined time period in order to establish a third electrical reference level; allowing said third electrical reference level to change at said first rate relative to said first electrical reference level; storing a second time period T2 that is representative of a time that expires between said step of again-unclamping said second electrical reference level until said first and third electrical reference levels become equal; again-re-establishing said first and second electrical reference levels; once-again-unclamping said second electrical reference level; again-changing said second electrical reference level at said second rate that is higher than said first rate for a time period that is related to said actual-flight-time of said pulse toward said target in order to establish a fourth electrical reference level; allowing said fourth electrical reference level to change at said first rate relative to said first electrical reference level; storing a third time period T3 that is representative of a time that expires between said step of once-again-unclamping said second electrical reference level until said first and fourth electrical reference levels become equal; and computing a range to said target as a function of the quantity (T3-T1)/(T2-T1). - View Dependent Claims (30, 31, 32, 33, 34)
-
-
35. Apparatus for determining a range to a target, said range being based upon an actual-flight-time of a pulse that is directed toward said target, said method comprising the sequential steps of:
-
means for establishing first and second electrical reference levels; means for initially-unclamping said second electrical reference level; means for allowing said second electrical reference level to change at a first rate relative to said first electrical reference level; means for storing a first time period T1 that is representative of a time that expires between said step of initially-unclamping said second electrical reference level until said first and second electrical reference levels become equal; means for re-establishing said first and second electrical reference levels; means for again-unclamping said second electrical reference level; means for changing said second electrical reference level at a second rate that is higher than said first rate for a predetermined time period in order to establish a third electrical reference level; means for allowing said third electrical reference level to change at said first rate relative to said first electrical reference level; means for storing a second time period T2 that is representative of a time that expires between said step of again-unclamping said second electrical reference level until said first and third electrical reference levels become equal; means for again-re-establishing said first and second electrical reference levels; means for once-again-unclamping said second electrical reference level; means for again-changing said second electrical reference level at said second rate that is higher than said first rate for a time period that is related to said actual-flight-time of said pulse toward said target in order to establish a fourth electrical reference level; means for allowing said fourth electrical reference level to change at said first rate relative to said first electrical reference level; means for storing a third time period T3 that is representative of a time that expires between said step of once-again-unclamping said second electrical reference level until said first and fourth electrical reference levels become equal; and means for computing a range to said target as a function of the quantity (T3-T1)/(T2-T1). - View Dependent Claims (36, 37, 38, 39, 40)
-
Specification