KR101704021B1 - Method for clipping of digital signal and apparatus for the same - Google Patents

Abstract

The present invention relates to a digital signal clipping method for reducing a digital signal of a predetermined size or more in a digital signal, and an apparatus therefor. The digital signal clipping apparatus of the present invention is characterized by clipping a coordinate value of an input signal to a specific one side of a polygon through symmetric movement of coordinates.

Clipping, Octagon, Coordinate Shift, Flip

Description

[0001] METHOD FOR CLIPPING OF DIGITAL SIGNAL AND APPARATUS FOR THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of digital signal processing and relates to a digital signal clipping method and apparatus therefor for reducing a digital signal over a predetermined size.

Generally, in the process of processing a digital signal, the following equation (1) is used when clipping the input signal x = a + jb based on the limited size A.

In Equation (1), y denotes a clipped signal.

의 계산을 수행하는 과정이 필요하다. 이는 하드웨어(H/W; hardware)의 복잡도를 증가시킨다. 특히, ASIC(application-specific integrated circuit) 또는 FPGA(field programmable gate array)에서 클리핑을 구현할 경우 많은 로직(logic) 회로가 필요해 자원 손실이 발생하는 문제점이 있다.In FIG. 1, it can be seen that the x signal outside the circle is clipped by the y signal at the circle boundary. In order to perform the clipping process,

Is required to perform the calculation of < RTI ID = 0.0 > This increases the complexity of hardware (H / W). In particular, when clipping is implemented in an application-specific integrated circuit (ASIC) or an FPGA (field programmable gate array), a lot of logic circuits are required, which causes resource loss.

The present invention provides a digital signal clipping method and apparatus therefor for reducing a digital signal over a predetermined size.

The digital signal clipping apparatus of the present invention clips the coordinate value of the passage input signal to a specific one side of the polygon by symmetrical movement of coordinates.

Further, the digital signal clipping apparatus of the present invention forms a clipping signal by rotating a coordinate value of an input signal and then clipping the coordinate value of the input signal to a specific one side of a polygon, and rotating the coordinate value of the input signal in a direction opposite to a direction in which the coordinate value of the input signal is rotated. do.

According to another aspect of the present invention, there is provided a digital signal clipping method including: a) performing a symmetric shift on a coordinate value of an input signal; And b) clipping the coordinate values of the symmetrically shifted input signal to a particular one of the polygons.

According to another aspect of the present invention, there is provided a digital signal clipping method including: a) rotating a coordinate value of an input signal using a polygon; b) clipping the coordinate value of the rotationally-shifted input signal to a specific side of the polygon; And c) forming a clipping signal by rotating the coordinate value of the clipped input signal in a direction opposite to a direction of rotating the input signal coordinate value.

According to the present invention, a complicated hardware structure for calculating the clipping signal and waste of resources can be reduced, and an optimized clipping signal can be obtained. Moreover, since the hardware structure is simplified, the cost of the product can be lowered, and the economical effect can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail if they obscure the subject matter of the present invention.

FIG. 2 is a diagram illustrating a regular octagon for digital signal clipping according to an embodiment of the present invention. Referring to FIG. 2, when the clipping boundary value is a, the coordinates of the input signal are P (p, q), and the coordinates of the output signal are Q (p ', q'), Can be calculated using the following equation (2).

α + α + π / 4 = π

Calculating Equation (1) results in a value of? = 3? / 8.

In Fig. 2, it can be expressed by the equation of the line f (x) = - tan a (x-a) and can be expressed by the equation g (x) = (q / p) x of the straight line OP. Therefore, the coordinates of Q (p ', q') are the solutions of f (x) = g (x). The process of solving f (x) = g (x) is shown in Equation (3).

In Equation (3), it has a fixed value of? = 3? / 8. Therefore, tan? Can use an approximate value of 2.4142. In other words, there is no need to actually perform the tan operation. 3 is an exemplary diagram illustrating input and output signals calculated according to an embodiment of the present invention.

In the embodiment of the present invention, it is assumed that the input signal P (p, q) is located between 0 and 45 degrees. Accordingly, when the input signal is located between 45 degrees and 360 degrees, the coordinate shift is performed between 0 degrees and 45 degrees, and the algorithm of the present invention should be applied. FIG. 4 is a diagram illustrating a process of performing coordinate movement between 0 degrees and 45 degrees through symmetric movement of coordinates according to the position of an input signal. When the input signal is located within the range of 45 to 90 degrees, the symmetric movement is performed with respect to the straight line y = x. When the input signal is located within the range of 90 to 135 degrees, First, symmetric motion is performed for the line y = -x and symmetric motion is performed for the line x = 0. If the input signal is located in the range of 135 to 180 degrees, a symmetric movement is performed with respect to the straight line x = 0. If the input signal is located within the range of 180 to 225 degrees, And performs a symmetric movement with respect to the straight line x = 0. When the input signal is located in the range of 225 to 270 degrees, symmetric movement is performed with respect to the straight line y = -x, and when the input signal is positioned within the range of 270 to 315 degrees, symmetric movement is performed with respect to the straight line y = -x Performs a symmetric movement with respect to the straight line y = 0, and performs a symmetric movement with respect to the straight line y = 0 when located in the range of 315 to 360 degrees.

5 is a flowchart illustrating an algorithm that can process coordinates of all input signals in the range of 0 to 360 degrees in consideration of coordinate shift according to an embodiment of the present invention. In FIG. 5, 'a' represents the boundary value of clipping and is variable. sign_x and sign_y represent signs of x and y, respectively, and have a value of -1 in case of a negative value and a value of 1 in case of a positive value. Since a digital signal is represented by a binary number (2`s complementary), the code can be easily grasped through the value of the most significant bit (MSB). Referring to FIG. 5, the values of the input signal P (x, y), clipping boundary values 'a' and 'tan (alpha)' are defined (S10). Signs x and y are defined in sign_x and sign_y, respectively (S20). If the value of y * sign_y is greater than the value of x * sign_x, the variable SWAP is set to 1 (S40), and the value of y * sign_y is compared with the value of x * sign_y If the value is smaller than the value of x * sign_x, the variable SWAP is set to 0 (S50). If the value of 'SWAP' is 1, the value of y * sign_y is stored in 'p', and the value of x * sign_x is stored in 'q' (S60). If the value of 'SWAP' is 0, the value of x * sign_x is stored in 'p', and the value of y * sign_y is stored in 'q' (S70). To calculate the values of p 'and q' in Equation (3), calculate the values of p_ = p * a * tan (alpha) / (q + p * tan (alpha)) and q_ = q / p * p_ S80). If the value of 'SWAP' is 1, x '= sign_x * p_ and y' = sign_y are set to x '= sign_x * q_ and y' = sign_y * p_ * q_ (S100). The clipping signal Q (x ', y') of the input signal P can be calculated using x 'and y' obtained in each case (S110).

6 and 7 illustrate input signal clipping using an octagonal shape. The distance between a circle and a square is always present, and if clipping is performed using only a square shape in a region where the distance between the circle and the square is large, too much signal information may be lost. When the original signal has a coordinate of P (1.5, 0.5), the coordinates after clipping are shifted to Q (0.70, 0.23), and the power of the signal is different from the power of 0.64 which is expected to be 0.55.

FIG. 8 is a view illustrating an improved clipping method in which signal coordinates are rotated to theta, then clipping is performed, and the coordinates are calculated by rotating the counterclockwise direction. In this way, the clipping error can be reduced because the clipping can be performed to a point close to the octagon and the circle.

9 is an exemplary view showing a rotational movement of coordinates. The coordinate P '(x ₂ , y ₂ ) after the rotation movement can be calculated using the following equation (4), assuming that the coordinate before the rotation movement is P (x ₁ , y ₁ ).

10 is a flowchart showing a procedure of a clipping method considering coordinate rotation. In Fig. 10, MAX_NUM_N indicates the maximum value of the number of times of attempting rotational movement, PI is a constant indicating the circularity, and Theta indicates the magnitude of the coordinate rotation. Referring to FIG. 10, an input signal P (x, y), N = 0 and a coordinate rotation proportional constant Delta are defined (S120). The value of N is compared with the value of MAX_NUM_N (S130). If the value of N is less than or equal to the value of MAX_NUM_N, Theta representing the coordinate rotation size is defined as PI / 4 * N * Delta or PI / 4 * (-1 * N) * Delta (S140, S150). The two theta values have the same absolute value and the opposite directions. Then, we define the new coordinates x ', y', which are rotated by theta as x '= x * cos (theta) - y * sin (theta) and y' = y * con (Theta) + x * sin do. The algorithm of FIG. 5 is performed using the new coordinates (x ', y') as input signals (S180, S190). And calculates the clipped signal Q (x, y). The clipped signal Q again performs a rotational movement in the opposite direction of Theta. Y * = y * cos (-1 * Theta) + x * (x * yta) - y * sin (-1 * Theta) (S220, S230). (S240, S250). Q1 = x '+ jy' and Q2 = x '+ jy' are stored as Q1 and Q2, respectively. The value of N is incremented by one (S270), and the process of step S130 is performed again. If the value of N is less than or equal to the value of MAX_NUM_N, the same steps S140 through S270 are performed. If the value of N is greater than the value of MAX_NUM_N, the maximum power among the values stored in Q [N] is searched (S280), and the final clipping signal Q is determined.

Although the clipping process of the input signal using the octagonal shape has been described in the present embodiment, the present embodiment can be implemented in a polygon such as a regular hexagonal shape or a regular hexagonal shape.

While the above methods have been described through specific embodiments, the methods may also be implemented as computer readable code on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission via the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily deduced by programmers of the present invention.

While the invention has been described in connection with certain embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention . It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.

1 is an exemplary view showing a clipping process;

FIG. 2 is an exemplary diagram illustrating an octagon for digital signal clipping according to an embodiment of the present invention; FIG.

FIG. 3 is an exemplary view showing input and output signals calculated according to an embodiment of the present invention; FIG.

FIG. 4 is an exemplary diagram illustrating a process of symmetric shifting of coordinates for clipping of a signal according to an embodiment of the present invention; FIG.

5 is a flowchart illustrating a clipping method considering coordinate shift according to an embodiment of the present invention.

6 and 7 illustrate an input signal clipping using a regular octagon according to an embodiment of the present invention.

8 is an exemplary view showing a clipping method according to an embodiment of the present invention;

FIG. 9 is an exemplary view showing rotational movement of coordinates according to an embodiment of the present invention; FIG.

10 is a flow chart illustrating a procedure of a clipping method considering coordinate rotation according to an embodiment of the present invention.

Claims (14)

CLAIMS 1. A digital signal clipping device, Clipping the coordinate value of the input signal to a specific side of the polygon by using the symmetric movement of the coordinates, Assuming that the coordinates of the input signal are (p, q), the coordinates of the clipped signal are (p ', q') and the clipping boundary values are a and a = 3π / 8, Digital signal clipping device.

The method according to claim 1, Wherein the polygon has a regular octagonal shape. delete The method according to claim 1, When the coordinates of the input signal are located in a range of 45 to 90 degrees, a symmetric movement is performed with respect to a straight line y = x, and when the input signal is positioned within a range of 90 to 135 degrees, a symmetric movement is performed with respect to a straight line y = Symmetric movement is performed with respect to the backward line x = 0, and when the position is within the range of 135 to 180 degrees, the linear movement is performed with respect to the line x = 0. When the position is within the range of 180 to 225 degrees, A symmetric movement is performed with respect to a straight line x = 0, a symmetric movement is performed with respect to a straight line y = -x when it is located in a range of 225 to 270 degrees, A symmetric movement is performed with respect to a straight line y = -x and then a symmetrical movement is performed with respect to a straight line y = 0, and when the position is within a range of 315 to 360 degrees, a symmetric movement is performed with respect to a straight line y = Digital signal clipping to calculate the coordinates of the signal Value. CLAIMS 1. A digital signal clipping device, A clipping signal is formed by rotating the coordinate value of the input signal and then clipping the coordinate value of the input signal to a specific one side of the polygon and rotating the coordinate value of the input signal in a direction opposite to the rotating direction, Assuming that the coordinates of the input signal are (p, q), the coordinates of the clipped signal are (p ', q') and the clipping boundary values are a and a = 3π / 8, Digital signal clipping device.

The digital signal clipping apparatus according to claim 5, wherein the polygon has a regular octagonal shape. 7. The method of claim 6, If the coordinates before the rotational movement are P (x ₁ , y ₁ ), the coordinates after the rotational movement are P '(x ₂ , y ₂ ), the angle of the coordinate P is α and the angle of the coordinate P' And the coordinate P 'after the rotation and movement is calculated using the following equation.

CLAIMS 1. A digital signal clipping method in a digital signal clipping apparatus, a) performing the symmetric shift of the digital signal clipping device with respect to the coordinate value of the input signal; And b) clipping the coordinate value of the symmetrically shifted input signal to a particular side of the polygon, Assuming that the coordinates of the input signal are (p, q), the coordinates of the clipped signal are (p ', q') and the clipping boundary values are a and a = 3π / 8, Clipping method of digital signal calculated using equation.

The digital signal clipping method according to claim 8, wherein the polygon is a polygon. 10. The method of claim 9, wherein step a) When the coordinates of the input signal are located in a range of 45 to 90 degrees, a symmetric movement is performed with respect to a straight line y = x, and when the input signal is positioned within a range of 90 to 135 degrees, a symmetric movement is performed with respect to a straight line y = Symmetric movement is performed with respect to the backward line x = 0, and when the position is within the range of 135 to 180 degrees, the linear movement is performed with respect to the line x = 0. When the position is within the range of 180 to 225 degrees, A symmetric movement is performed with respect to a straight line x = 0, a symmetric movement is performed with respect to a straight line y = -x when it is located in a range of 225 to 270 degrees, A symmetric movement is performed with respect to a straight line y = -x and then a symmetrical movement is performed with respect to a straight line y = 0, and when the position is within a range of 315 to 360 degrees, a symmetric movement is performed with respect to a straight line y = Digital signal clipping to calculate the coordinates of the signal Law. delete CLAIMS 1. A digital signal clipping method in a digital signal clipping apparatus, a) the digital signal clipping apparatus rotates a coordinate value of an input signal using a polygon; b) the digital signal clipping apparatus clipping the coordinate value of the rotationally-shifted input signal to a specific one side of the polygon; And c) forming a clipping signal by rotating the coordinate value of the clipped input signal by rotating the coordinate value of the clipped input signal in a direction opposite to a direction of rotating the input signal coordinate value, The step b) Assuming that the coordinates of the input signal are (p, q), the coordinates of the clipped signal are (p ', q') and the clipping boundary values are a and a = 3π / 8, Clipping method of digital signal calculated using equation.

13. The digital signal clipping method according to claim 12, wherein the polygon has a regular octagonal shape. 14. The method of claim 13, If the coordinates before the rotational movement are P (x ₁ , y ₁ ), the coordinates after the rotational movement are P '(x ₂ , y ₂ ), the angle of the coordinate P is α and the angle of the coordinate P' The coordinate P 'after the rotation and movement is calculated using the following equation.

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