Two angle range and altitude measurement system and methods

• US 4,626,861 A
• Filed: 09/28/1984
• Issued: 12/02/1986
• Est. Priority Date: 09/28/1984
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Wiley, Edward R.
• Primary Examiner(s): Blum, Theodore M.
• Assistant Examiner(s): Issing, Gregory C.
• Application Number:
  US06/655,705
• Time in Patent Office: 795 Days
• Field of Search: 343/450, 343/453, 343/458, 343/462, 343/465, 343/11 VB, 343/387, 343/428, 343/430, 364/449, 364/458
• US Class Current: 342/458
• CPC Class Codes: G01S 11/04 using angle measurements
• CPC Class Codes: G01S 2205/03 Airborne
• CPC Class Codes: G01S 3/66 Narrow-beam systems producing in the receiver a pulse-type envelope signal of the carrier wave of the beam, the timing of which is dependent upon the angle between the direction of the transmitter from the receiver and a reference direction from the receiver; Overlapping broad-beam systems defining in the receiver a narrow zone and producing a pulse-type envelope signal of the carrier wave of the beam, the timing of which is dependent upon the angle between the direction of the transmitter from the receiver and a reference direction from the receiver
• CPC Class Codes: G01S 5/0249 Determining position using measurements made by a non-stationary device other than the device whose position is being determined

Abstract

A passive system and related methods for detecting range and/or elevation of a target by using an X beam antenna system and by measuring the time delay between receipt of signals in the two planes of the X beam which are received directly from the target and by measuring the time delay between receipt of signals in the two planes of the X beam which signals are emitted by the target but reflected from a remote surface. By knowing these two time delays, the height of the antenna system, the fixed angle between the two planes of the X beam and the rate of rotation of the X beam, a direct calculation is established to determine the range and/or elevation of the target.

Claims

1. A system for detecting the range and elevation of a target comprising:

a. an antenna system having first and second planes of receipt which are inclined a fixed angle (θ

) from one another, said antenna system being located along the line of intersection of said planes and said antenna system including means for sweeping said line of interesection at a known rate of sweep (τ

);

b. means for measuring the delay (T₁) between receipt of signals in said first and then in said second planes which are emitted from a target and received directly by said antenna system;

c. means for measuring the delay (T₂) between receipt of signals in said first and then in said second planes which are emitted by said target and received by said antenna system after being reflected from a remote surface;

d. means for measuring the height (R_H) of said receiver; and

e. means for calculating the range and/or elevation of said target in response to θ

, τ

, T₁, T₂ and R_H.

2. The system of claim 1 wherein said means for calculating determines slant target range R_S using the relationship:

##EQU6## where;

space="preserve" listing-type="equation">α

.sub.D =tan.sup.-1 [sin (T.sub.1 ·

τ

)/tan (θ

)];

and

space="preserve" listing-type="equation">α

.sub.G =tan.sup.-1 [sin (T.sub.2 ·

τ

)/tan (θ

)].

3. The system of claim 1 wherein said means for calculating determines target elevation T_H using the relationship:

space="preserve" listing-type="equation">T.sub.H =R.sub.H -R.sub.S ·

sin (α

.sub.D)

where;

##EQU7##

4. The system of claim 2 wherein said means for calculating determines target elevation T_H using the relationship:

space="preserve" listing-type="equation">T.sub.H =R.sub.H -R.sub.S ·

sin (α

.sub.D)

5. The system of any one of claims 1 to 4 wherein said line of intersection is parallel to a line which is tangent to the surface of the earth at a point directly below said antenna system.

6. The system of any one of claims 1 to 4 wherein said line of intersection also intersects the horizon as seen from said antenna system.

7. A method for detecting the range and elevation of a target employing an antenna system having first and second planes of receipt which are inclined a fixed angle (θ

) from one another, said antenna system being located along the line of intersection of said planes and said antenna system including means for sweeping said line of intersection at a known rate of sweep (τ

), the method comprising the steps of;

a. measuring the delay (T₁) between receipt of signals in said first and then in said second planes which are emitted from a target and received directly by said antenna system;

b. measuring the delay (T₂) between receipt of signals is said first and then in said second planes which are emitted by said target and received by said antenna system after being reflected from a remote surface;

c. measuring the height (R_H) of said receiver; and

d. calculating the range and/or elevation of said target in response to θ

, τ

, T₁, T₂ and R_H.

8. The method of claim 7 wherein said step of calculating includes determining the slant target range R_S using the relationship:

##EQU8## where;

space="preserve" listing-type="equation">α

.sub.D =tan.sup.-1 [sin (T.sub.1 ·

τ

)/tan (θ

)];

and

space="preserve" listing-type="equation">α

.sub.G =tan.sup.-1 [sin (T.sub.2 ·

τ

)/tan (θ

)].

9. The method of claim 7 wherein said step of calculating includes determining the target elevation T_H using the relationship:

space="preserve" listing-type="equation">T.sub.H =R.sub.H -R.sub.S ·

sin (α

.sub.D)

where;

##EQU9##

10. The method of claim 8 wherein said step of calculating includes determining said target elevation T_H using the relationship:

space="preserve" listing-type="equation">T.sub.H =R.sub.H -R.sub.S ·

sin (α

.sub.D).