OBSCURATION DELINEATION CIRCUITRY

• US 3,671,729 A
• Filed: 03/10/1971
• Issued: 06/20/1972
• Est. Priority Date: 03/10/1971
• Status: Expired due to Term

• Current Assignee: Foss Britton Lux, 23531 Seneca
• Original Assignee: Foss Britton Lux, 23531 Seneca
• Inventors: Foss Britton Lux, 23531 Seneca
• Primary Examiner(s): Joseph F. Ruggiero
• Application Number:
  US05/122,707
• Time in Patent Office: 468 Days
• Field of Search: 235/186,189 35/10.2,10.4,12
• US Class Current: 358/1.3
• CPC Class Codes: G06G 7/22 for evaluating trigonometric functions; for conversion of co-ordinates; for computations involving vector quantities trigonometric computations using simultaneous equations G06G7/34 for computations in the complex plane; G06G7/20, G06G7/28 take precedence

Abstract

A device for providing an indication, on a radial plot, of all the terrain obscured from the view of an assumed observer who is located at some reference elevation above the origin of the plot. The output is obtained by means of an X-Y plotter or coordinatograph. The stylus of the coordinatograph traces a series of radial straight lines from the point corresponding to the observation point. The stylus is lowered to provide a visible record if the terrain is visible from the observation point, and is raised to record a gap if the terrain is obscured or not visible. The device functions by storing a quantity representative of the largest value of the look angle, as the terrain is scanned from the center outward, and treats all terrain with a look angle smaller than any previous look angle as obscured.

Claims

1. An obscuration delineation circuit providing control signals to an automated chart analysis apparatus comprising in combination:

an AC resolver having a first and second input winding, a first and second output winding and a mechanical input shaft, said first and second input winding being coupled to said first and second output winding, said mechanical input shaft controlling the amount of coupling between said first and second input winding and said first and second output winding, said first and second input winding receiving an input signal from said chart analysis apparatus, said first and second output winding providing output signals, an AGC unit connected to said first and second output winding to receive said output signals, said AGC unit providing an output signal, an obscuration detection circuit to detect the polarity of said output signal from said AGC unit, said obscuration detection circuit providing an inhibit signal when said output signal from said AGC unit is negative, said inhibit signal being utilized by said chart analysis apparatus to indicate as obscure, the terrain being plotted, said inhibit signal being the stylus control signal to said chart analysis apparatus, said obscuration detection circuit providing a servo control signal, and, a servo amplifier and motor unit receiving said servo control signal, said servo unit being connected to said mechanical input shaft of said resolver, said servo unit controlling the amount of coupling between said resolver input and output windings.

2. An obscuration delineation circuit as described in claim 1 wherein said obscuration detection circuit comprises:

a first circuit to detect the polarity of said signal from said AGC uNit, said first circuit providing a control signal to inhibit motion of said servo unit in a negative direction when said AGC signal is negative, and, a second circuit to detect an error signal from said AGC unit more negative than required for said inhibiting signal, said second circuit providing said terrain obscuration signal.

3. An obscuration delineation circuit as described in claim 1 further including a potentiometer having a reference voltage applied, said potentiometer being adjusted to provide an output voltage which represents the height of an object, an amplifier demodulator unit to sum said output voltage with said output signal from said resolver, said summed signal being the output of said amplifier demodulator, and an obscuration detection circuit connected to said amplifier demodulator unit to receive said sum signal, said obscuration detection circuit providing an output pen lift signal, a resolver driven by said arctangent servo which provides corrections to the height comparison circuit when the look angle is not horizontal.