Passive millimeter wave traffic sensor
First Claim
1. A sensing device for the passive sensing of millimeter wave ("MMW") signals emanating from a predetermined field of view for determining therefrom information relating to the presence and absence of moving vehicles and a velocity and a length of each said vehicle within said predetermined field of view, said sensing device comprising:
- antenna means for receiving said MMW signals;
low noise amplifier means for amplifying a portion of said MMW signal;
detector means for generating a time varying analog signal from said amplified portion of said amplified MMW signal;
analog signal processing means for processing said time varying analog signal;
analog-to-digital converter means for converting said time varying analog signal to a digital signal; and
digital signal processing means for processing said digitized signal along a plurality of processing paths to determine information relating to said presence and absence of said moving vehicles and said velocity and said length of each said vehicle within said predetermined field of view.
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Accused Products
Abstract
A passive millimeter traffic sensor sensing device for the direct detection of the movement or presence of vehicles within a predetermined field of view. The sensing device includes MMIC type sensing devices and heterodyne receivers, which include an antenna, local oscillator, mixer, a plurality of intermediate frequency amplifiers, a detector, and appropriate signal conditioning circuitry to detect signals in the millimeter wave region emanating from various objects such as motor vehicles, and also millimeter wave signals from the atmosphere reflected off of such objects. Thus, the sensing device detects the natural millimeter wave radiation coming from a scene. The intensity of the radiation is related to the effective radiometric temperatures in the scene which cause various objects, which have varying characteristics as both millimeter wave emitters and as reflectors, to appear as varying signal amplitudes to the sensing device. The sensing device may be mounted at a highway overpass or atop a light pole adjacent a highway and can provide information relating to the presence of a vehicle, whether moving or stationary, as well as the approximate length of the vehicle and approximate speed at which the vehicle travels through the sensing device'"'"'s predetermined field of view.
35 Citations
21 Claims
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1. A sensing device for the passive sensing of millimeter wave ("MMW") signals emanating from a predetermined field of view for determining therefrom information relating to the presence and absence of moving vehicles and a velocity and a length of each said vehicle within said predetermined field of view, said sensing device comprising:
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antenna means for receiving said MMW signals; low noise amplifier means for amplifying a portion of said MMW signal; detector means for generating a time varying analog signal from said amplified portion of said amplified MMW signal; analog signal processing means for processing said time varying analog signal; analog-to-digital converter means for converting said time varying analog signal to a digital signal; and digital signal processing means for processing said digitized signal along a plurality of processing paths to determine information relating to said presence and absence of said moving vehicles and said velocity and said length of each said vehicle within said predetermined field of view. - View Dependent Claims (2)
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3. A passive millimeter wave sensing apparatus for sensing the presence and absence of moving or stationary vehicles in a predetermined field of view and a velocity and a length of each said vehicle, said sensing device comprising:
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antenna means for receiving a millimeter wave signal from the atmosphere reflected by a surface of said vehicle and a millimeter wave signal emitted from a surface upon which said vehicle is traveling on within a predetermined field of view; oscillator means for generating an oscillating signal having a frequency within a range of about 35 GHz to 94 GHz, inclusive; mixer means responsive to said oscillator means and said detected millimeter wave signals for mixing said oscillating signal and said detected millimeter wave signals and generating an intermediate frequency output signal; amplifier means responsive to said intermediate frequency output signal of said mixer means for amplifying said signal; detector means for detecting at least a portion of said millimeter wave signal and generating a time varying analog signal in accordance therewith; analog signal processing means for processing said time varying analog signal; analog-to-digital converter means for converting said time varying analog signal to a digital signal; digital signal processing means for processing said digital signal along independent first and second processing paths; threshold detector means disposed in said first processing path and being responsive to said digital signal, said digital signal being indicative of the presence and absence of moving and stationary vehicles for detecting a threshold response; and digital differentiator means disposed in said second processing path and being responsive to said digital signal for generating a differentiated digital signal from said digital signal, said differentiated digital signal being indicative of the velocity and the length of each said vehicle within said predetermined field of view. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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11. A passive millimeter wave sensor sensing device for detecting moving objects within a predetermined field of view, said sensing device comprising:
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an antenna for receiving millimeter wave signals and restricting a reception of said received millimeter wave signals to millimeter wave signals emanating from within said predetermined field of view; oscillator means for generating an oscillating reference signal in the range of about 35 to 94 GHz, inclusive; mixer means responsive to said oscillator means and said antenna for receiving said millimeter wave signal and said oscillating reference signal and generating a first output signal therefrom; intermediate frequency amplifier means responsive to said mixer means for receiving and amplifying said first output signal and generating a second output signal therefrom having a predetermined bandwidth from about 1 GHz to 2 GHz, inclusive; detector means responsive to said second output signal from said intermediate frequency amplifier means for detecting the presence of said received millimeter wave signals and generating a third output signal, said third output signal being a time varying analog signal; analog signal processing means for processing said time varying analog signal; analog-to-digital converter means for converting said third output analog signal at said detector means to a digital signal in the form of a digital serial bit stream; digital signal processing means for processing said digital serial bit stream along independent first and second digital processing paths; threshold detector means disposed in said first digital processing path and being responsive to said digital serial bit stream, with a first digital signal being indicative of absence of said object and a second digital signal being indicative of said presence of said object; and digital differentiator means disposed in said second digital processing path and being responsive to said digital bit stream for generating a differentiated digital serial bit stream from said digital serial bit stream, with said differentiated digital serial bit stream amplitude swings being indicative of said velocity of said object, and a time separation between maximum amplitude peaks of said differentiated digital bit stream being indicative of a length of said object. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method for detecting the presence and absence of stationary objects and a velocity and a length of moving objects within a desired field of view, said method comprising the steps of:
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defining said desired field of view; passively receiving millimeter wave signals emanating from said desired field of view; filtering said received millimeter wave signals to remove signals outside of a range encompassing received signals having frequencies between about 35 GHz to 94 GHz, inclusive; detecting the presence of millimeter wave signals falling within said range of frequencies; defining a first processing path for detecting said presence and absence of said objects in response to said millimeter wave signals received within said frequency range between about 35 GHz to 94 GHz, inclusive, within said field of view; and defining a second processing path for detecting said velocity and length of each one of said moving objects in response to said millimeter wave signals received within said frequency range between about 35 GHz to 94 GHz, inclusive, within said desired field of view. - View Dependent Claims (18)
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19. A method for detecting moving and stationary vehicles within a desired field of view, said method comprising the steps of:
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using an antenna to receive millimeter wave signals emanating from an area in accordance with a desired field of view; filtering said received millimeter wave signals to remove signals outside of range encompassing received signals having frequencies between about 35 GHz to 94 GHz, inclusive; using a millimeter wave detector to detect millimeter wave signals having frequencies in accordance with said frequency range from said received millimeter wave signals; causing said millimeter wave detector to generate a time varying analog signal in accordance with said detected millimeter wave signals; using signal conditioning means to convert said time varying analog signal to a digital serial bit stream; defining a first processing path being responsive to said digital serial bit stream, with a first digital signal of said serial bit stream being indicative of said absence of said vehicle when said received millimeter wave signal is higher than predetermined threshold and a second digital signal of said serial bit stream being indicative of said presence of said vehicle when said received millimeter wave signal is lower than said predetermined threshold; and defining a second processing path being responsive to said digital serial bit stream for generating a differentiated digital serial bit stream from said digital serial bit stream, with said differentiated digital serial bit stream having amplitude swings being indicative of said velocity of said vehicle and a time separation between maximum amplitude peaks of said differentiated digital bit stream being indicative of a length of said vehicle. - View Dependent Claims (20, 21)
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Specification