Cross correlated doppler radar/infra red velocity and presence sensor

• US 4,317,117 A
• Filed: 07/20/1979
• Issued: 02/23/1982
• Est. Priority Date: 07/20/1979
• Status: Expired due to Term

• Current Assignee: Norman E. Chasek
• Original Assignee: Norman E. Chasek
• Inventors: Chasek, Norman E.
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US06/059,332
• Time in Patent Office: 949 Days
• Field of Search: 343/6 ND, 343/8
• US Class Current: 342/53
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/91 for traffic control G01S13/93 takes precedence

Abstract

A doppler radar and infra red sensor focused by common means onto a region, will, with appropriate cross correlation, provide improved velocity and presence sensing in a complex uncontrolled environment. The illustrative overhead, roadside traffic sensor employs a common microwave/infra red parabolic reflector and illuminating feed. The sensor can be conveniently mounted onto utility poles without cutting up the road or hanging overhead arbors. The velocity and presence data it provides can be used to determine vehicular headway, density, volume, vehicle size, aggregate momentum, aggregate congestion, platoon arrival, queue length, etc. This novel sensor reduces spurious indications, permits oblique angle viewing of vehicles, reduces doppler transmitter power levels so as to be well below normally accepted environmentally safe levels, and discriminates against vehicles moving in the wrong direction. The improved information will make possible better adaptive traffic signal timing methods to reduce fuel consumption and auto emissions. An additional feature provided by this sensor is that it detects emergency and mass transit vehicles to expedite their safe movement.

Claims

1. A method for sensing presence and velocity of objects expected to pass through or reside in a predetermined region comprising the steps of:

aiming a doppler radar beam at said predetermined region,

sensing radar reflections from objects moving through said region,

beating the frequency of said reflections with the transmitted frequency and using the presence of a beat frequency to indicate a moving object in said region,

measuring the beat frequency to indicate the velocity of the object moving through said region,

sensing infra red emissions from said region in the absence of any object, for the purpose of establishing a reference level, and

indicating presence of said object in said region by the IR emissions which are different from said reference level.

2. Apparatus for sensing the presence and velocity of an object in a region comprising,

a protective housing including a window that passes microwave and infra red radiation,

a parabolic reflector within said housing for focusing both microwave and infra red radiation arriving through said window,

a feed means located at the focus of said parabolic reflector for illuminating said reflector, said feed means including an infra red level sensing element and a coupler for a doppler radar receiver-transmitter,

a doppler radar mixer-transmitter connected to said coupler,

a plurality of low frequency amplifiers one of said amplifier being connected to said radar mixer-transmitter and the other being connected to said infra red sensing element,

a sample and hold circuit to retain voltage samples representative of IR emissions from said region when free of objects to establish a reference level,

a circuit that establishes presence by indicating whenever IR levels differ from said reference following a doppler radar indication of entry into said region and,

a circuit for measuring the doppler beat frequency when coincident with said presence indication.