JPS56166659A - Signal detector - Google Patents

Abstract

PURPOSE:To obtain a suitable signal detector with less process delay by finding a logarithmic tolerance ratio function by using causal filters in a system depending upon a message in which a noise is transmitted like an optical fiber communication system. CONSTITUTION:An input signal r(t) is inputted from a terminal 3 to causal filters 38 and 39 and a delay circuit 37. From estimated value outputs 40 and 41 and a delay output 12, an output passed through adding circuits 21, 22 and 24, and load multiplying circuits 42 and 43 is inputted to adding and composing circuit 35, and outputs of multiplying circuits 14 and 15 are inputted to the circuit 35 via square circuits 16 and 17 and also inputted to the circuit 35 via square circuits 18 and 19. An output obtained from the output of the circuit 35 by integration 26 is sampled 27 with a sampling clock fs and then compared with a preset threshold by a comparing circuit 28 to obtain a detection signal with a logical level which corresponds to a dependent noise. A thus generated logarithmic tolerance ratio function is used to obtain a suitable and less-delay signal detecting circuit.