Method for reducing angular blur in radar pictures

• US 20060066475A1
• Filed: 01/25/2005
• Published: 03/30/2006
• Est. Priority Date: 01/27/2004
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Tullsson, Bert-Eric
• Granted Patent: US 7,236,125 B2
• Time in Patent Office: Days
• US Class Current: 342/159
• CPC Class Codes: G01S 13/426 Scanning radar, e.g. 3D radar G01S13/66 takes precedence
• CPC Class Codes: G01S 7/4026 Antenna boresight
• CPC Class Codes: G01S 7/403 in azimuth, i.e. in the horizontal plane
• CPC Class Codes: G01S 7/4034 in elevation, i.e. in the vertical plane

Abstract

The invention refers to a method for reducing angular blur in radar pictures achieved in range bin based detection systems. A variable S(x,y) such as amplitude, power or the like is measured as a function of an angle x and a distance y. According to the invention an expression of the type:
corrected angular position=angular position+angle correction is determined in each range bin for a plurality of angular values x, the term “angle correction” comprising derivative(s) of first or higher order of the variable S(x). The variable measured at the angular position “angular position” is the moved to the variable in the angular position “corrected angular position” and the moved variable and the variable in “corrected angular position” are processed by adding, maximizing or the like.

Claims

1. Method for reducing angular blur in radar pictures achieved in range bin based detection systems, a variable S(x,y) such as amplitude, power or the like being measured as a function of an angle x and a distance y or when x and y only assumes discrete values a variable S(i,j) with i₁≦

i≦

i₂ and j₁≦

i≦

j₂, the abbreviated way of writing S(x) or S(i) being used when the distance is implicit or irrelevant, characterized in that in each range bin for a plurality of angular values x an expression of the type;

corrected angular position=angular position+angle correction

is determined, and in which “

angle correction”

comprises (partial) derivative(s) of first or higher order S′

(x), S″

(x), . . . of the measured variable S(x) as a function of the angle x and in which the variable measured at the angular position “

angular position”

then is moved to the variable in the angular position “

corrected angular position”

, the moved variable and the variable in “

corrected angular position”

being processed by adding, maximizing or the like.

2. Method as claimed in claim 1, characterized in that only quotients q of the type S′

(x)/S(x) are comprised in the expression “

angle correction”

.

3. Method as claimed in claims claim 1, characterized in that the derivatives are estimated numerically from measured values of S(x).

4. Method as claimed in claim 3, characterized in that for the estimation of derivatives such as S′

(x) finite differences in angular direction Δ

S/Δ

x are used.

5. Method as claimed in claim 4, characterized in that averaged or low-pass filtered finite differences are used.

6. Method as claimed in claim 1, characterized in that information from the variable S(x) are only used for such values of x in which the variable S(x) exceeds a certain given threshold t.

7. Method as claimed in claim 1, characterized in that a quotient q of the type S′

(x)/(S(x)+t) are comprised in the expression “

angle correction”

.