Title:
CIRCULAR LIMITTER
Document Type and Number:
Japanese Patent JPH06204953
Kind Code:
A
Abstract:
PURPOSE: To improve the performance of system by reducing the effects of distortion upon signal points outside a signal point group in a high speed communication system by limiting a reception signal point at one part of a signal space. CONSTITUTION: A modem 200 receives a signal with multilevel amplitude modulation from a communication channel through a joint line 204, inputs that signal through a demodulator 205 to an equalizer 210 and equalizes it. An output signal, that expresses the coordinate values of specified points (x) and (y) from the equalizer 210, is inputted to multipliers 240 and 245, are squared to become the signals x<2> and y<2> and become a signal x<2> +y<2> by addition at an adder 250. This value becomes the square of the distance from the reception origin of reception space to the occupied position of reception signal point. A differential signal r<2> -x<2> -y<2> : the difference of value x<2> +y<2> from r<2> is found from a limit signal [squared value of radius (r) of circle] by an adder 255, is compared by a comparator 260 as to whether or not this value is larger than '0'. When it is smaller than '0', a scaling factor α is set proportional to the difference, but when this value is larger than 0, and the output of the equalizer 210 is multiplied by α while multiplying α.
Inventors:
UIRIAMU RUISU BETSUTSU
KEISU ARAN SOODAAZU
KEISU ARAN SOODAAZU
Application Number:
JP16878393A
Publication Date:
July 22, 1994
Filing Date:
July 08, 1993
Export Citation:
Assignee:
AMERICAN TELEPHONE & TELEGRAPH
International Classes:
H04B15/00; H03F1/32; H03M13/23; H04L27/38; (IPC1-7): H04B15/00
Attorney, Agent or Firm:
Masao Okabe (2 outside)
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