ALONG TRACK TERRAIN AVOIDANCE CONTOURING SYSTEM

• US 3,810,175 A
• Filed: 01/17/1972
• Issued: 05/07/1974
• Est. Priority Date: 01/17/1972
• Status: Expired due to Term

• Current Assignee: William H. Bell
• Original Assignee: William H. Bell
• Inventors: Bell, William H.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Birmiel, H. A.
• Application Number:
  US05/218,217
• Time in Patent Office: 841 Days
• Field of Search: 343/7TA,7.3,5EM
• US Class Current: 342/183
• CPC Class Codes: G01S 13/935 for terrain-avoidance

Abstract

A terrain clearance or following system that provides terrain clearance information in depth from large elevation depression angles out along the projected aircraft ground track to the horizon. The aircraft projected ground track is displayed on a cathode ray tube by a heavy along track line and the intersection of the aircraft velocity vector with the terrain is displayed by the intersection of the along track line and a flight path reference line. The range to the top of a first hill is displayed at the end of a first segment of the along track line and the distance across the valley between first and second hills is displayed as a blank space between the first and a second segment of the along track line. The range to the top of succeeding hills is displayed by additional segments of the along track line. This system operates with simultaneous display of a radar line of sight range line and a terrain clearance reference line representing an imaginary clearance plane at a selected distance below the aircraft. A down look reference line representing the range to the clearance plane at the maximum depression angle may also be displayed.

Claims

1. An obstacle indicating system for use with an aircraft comprising radar means including a scanning antenna having a boresight axis, means to control said antenna to scan in azimuth and in elevation, signal forming means coupled to said radar means to form a range gate when transmitted energy is received on said boresight axis, display means having azimuth and elevation deflection controls responsive to said means to control said antenna and said radar means and including an intensity control responsive to said signal forming means to display a radar line-of-sight range, signal intensifying means coupled to the azimuth deflection control during said vertical scans of said antenna, circuit means for determining when the antenna boresight axis is coincident with the aircraft velocity vector in elevation and coupled to said signal intensifying means and to said intensity control to develop a flight path reference line on said display, and crab angle correction means coupled to said scanning antenna so that said antenna when scanning in elevation scans along the aircraft velocity vector and said flight path reference line is formed at an angle on said display means representative of said crab angle.

2. An obstacle indicating system for use with an aircraft comprising radar means including a scanning antenna having a boresight axis, means to control said antenna to scan in azimuth and in elevation, signal forming means coupled to said radar means to form a range gate when transmitted energy is received on said boresight axis, display means having azimuth and elevation deflection controls responsive to said means to control said antenna and said radar means and including an intensity control responsive to said signal forming means to display a radar line-of-sight range, signal intensifying means coupled to the azimuth deflection control during said vertical scans of said antenna, circuit means for determining when the antenna boresight axis is coincident with the aircraft velocity vector in elevation and coupled to said signal intensifying means and to said intensity control to develop a flight path reference line on said display, a source of sweep voltages for providing an azimuth and a range sweep voltage for controlling said azimuth and elevation controls, and circuit means for relating a voltage representing a predetermined range to a selected clearance plane below the aircraft to the range sweep voltage and coupled to said intensity control so that at coincidence a down look reference line is formed on said display.

3. A system operable with a moving aircraft to indicate the presence of objects along the path thereof, the system including a scannable monopulse antenna means, radar means for developing a line-of-sight range gate and a display having azimuth and elevation deflection means responsive to the scanning of said antenna and having an intensity control means coupled to said radar means for receiving said line-of-sight range gate comprising antenna control means coupled to said antenna to control said antenna to scan Sequentially in azimuth and in elevation, a source of jizzle voltage coupled to the azimuth deflection means of said display and coupled to said antenna control means to apply said jizzle voltage to said azimuth deflection means when said antenna scans in elevation, a terrain clearance reference line circuit for dividing a distance h between the aircraft and a clearance plane below the craft by a function of the radar line-of-sight angle with the clearance plane, for a selected radar down look angle to apply a pulse to the intensity control means of said display during azimuth scan to form a terrain clearance reference line, and means coupled to said terrain clearance reference line circuit and to said antenna to select terrain avoidance or terrain clearance modes of operation.

4. The system of claim 3 further including a down look reference line circuit coupled to said terrain clearance reference line circuit and responsive to the azimuth scanning of said antenna to apply a signal to said intensity control means to provide a down look reference line on said display.