JPH05218774A - Digital amplitude limiter - Google Patents

Abstract

PURPOSE:To prevent information from being delivered in error by preventing fluctuation in a phase when an amplitude of a digital signal is limited. CONSTITUTION:The limiter is provided with an orthogonal-polar coordinate converter 1 converting an orthogonal coordinate of a digital signal into a polar coordinate, an amplitude limiter 2 limiting an amplitude of the digital signal whose coordinate is converted into a polar coordinate, and a polar - orthogonal coordinate converter 3 converting the polar coordinate into an orthogonal coordinate. The orthogonal-polar coordinate converter 1 converts the orthogonal coordinate into the polar coordinate, the amplitude limiter 2 limits only the amplitude component of the obtained amplitude component and the phase component and the polar-orthogonal coordinate converter 3 converts the polar coordinate again into an orthogonal coordinate to limit the amplitude of the digital signal without changing the phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital amplitude limiting device, and more particularly to a digital amplitude limiting device used in a digital transmission modulator / demodulator.

[0002]

2. Description of the Related Art In a conventional digital amplitude limiter, when limiting a vector of a certain amplitude, the amplitude of each component decomposed into components parallel to each axis of the Cartesian coordinates is independently amplified by an amplitude limiter. I have a limit. For example, as shown in FIG. 2, the orthogonal components of the input signal vector are Xi and Yi.
Then, the amplitude of each component is limited by the amplitude limiter 2, and the orthogonal components Xo and Yo of the output signal vector are obtained.

[0003]

When the phases of the input and output signal vectors are θi and θo, respectively, they are given by the following equations. θi = tan ⁻¹ (Yi / Xi) θo = tan ⁻¹ (Yo / Xo) Therefore, in the amplitude limiting device of FIG. 2, the phase of the input / output signal vector is prevented from changing even if the amplitude is limited. Therefore, the ratio of the orthogonal components of the input and output signal vectors must be constant (Yi / Xi = Yo / Xo).

However, in the conventional digital amplitude limiting device, since the quadrature component of the input signal vector is independently limited in amplitude, the ratio of the quadrature component may not be constant, and the input signal vector and the output signal vector may not be constant. The phase differs from the signal vector. Therefore, when the information is transmitted by the phase, there is a problem that the information may be erroneously transmitted through the amplitude limiter. It is an object of the present invention to provide a digital amplitude limiting device which prevents phase fluctuations and prevents information from being erroneously transmitted.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a Cartesian-Polar coordinate converter for converting Cartesian coordinates of a digital signal into polar coordinates,
An amplitude limiter for limiting the amplitude of the digital signal converted into polar coordinates and a polar-orthogonal coordinate converter for converting polar coordinates into rectangular coordinates are provided.

[0006]

Function: The rectangular coordinates of the digital signal are converted into polar coordinates, and only the amplitude component of the obtained amplitude component and phase component is limited by the amplitude limiter, and then the orthogonal coordinate is converted again, thereby limiting the amplitude. To execute.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, 1 is a rectangular-polar coordinate converter that converts rectangular coordinates into polar coordinates, 2 is an amplitude limiter that limits only the amplitude component of the amplitude component and phase component converted by the rectangular-polar coordinate converter 1, 3 Is a polar-orthogonal coordinate converter for converting polar coordinates to rectangular coordinates.

In this configuration, the orthogonal components Xi and Yi of the input signal vector are converted by the orthogonal-polar coordinate converter 1 into the amplitude component ri and the phase component θi. Next, the phase component θi
The amplitude limiter 2 limits the amplitude of only the amplitude component ri. The values at this time are θo (= θ
i) and ro. Then, by passing these values ro and θo through the polar-rectangular coordinate converter 3, the orthogonal components Xo and Yo of the output signal vector are obtained again. As a result, the amplitude can be limited without changing the phase of the input signal vector and the output signal vector, and it is possible to correctly transmit the information even when the information is transmitted by the phase. Become.

[0009]

As described above, according to the present invention, Cartesian coordinates are once converted into polar coordinates and then only the amplitude component is limited.
Since the coordinates are converted to the rectangular coordinates again, the amplitude can be limited without changing the phase. Therefore, even if the amplitude limiter is used when transmitting information by the phase, there is an effect that the information is not transmitted by mistake.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an amplitude limiting device of the present invention.

FIG. 2 is a block diagram of an example of a conventional amplitude limiting device.

[Explanation of symbols]

 1 Cartesian-polar coordinate converter 2 Amplitude limiter 3 Polar-rectangular coordinate converter

Claims (1)

[Claims] 1. A rectangular-polar coordinate converter for converting rectangular coordinates of a digital signal into polar coordinates, an amplitude limiter for limiting the amplitude of a digital signal converted into polar coordinates, and a polar-orthogonal coordinate for converting polar coordinates into rectangular coordinates. A digital amplitude limiting device comprising: a converter.