RECEPTION INPUT ELECTRIC FIELD STRENGTH DETECTION CIRCUIT

摘要

PURPOSE: To detect accurately an electric field strength by sampling a prescribed level (symbol point) of a received wave when the electric field strength of a received digital modulation wave such as a π/4 shift QPSK modulation wave whose instantaneous level is fluctuated is detected. ;CONSTITUTION: The detection circuit is provided with a logarithmic amplifier 1 receiving a digital modulation wave 101 whose instantaneous level is fluctuated and outputting a DC voltage 102 corresponding to its electric field strength, an A/D converter 2 receiving the DC voltage 102 and outputting a converted digital quantity 103, a clock recovery circuit 3 recovering a recovered clock 104 from the digital modulation wave 101 and a clock synchronization circuit 4 receiving the recovered clock 104, synchronizing it and outputting a sampling clock 105 having a timing coincident with a symbol point of the digital modulation wave 101, and the sampling clock 105 is used for the sampling timing of the A/D converter 2 so as to sample the symbol point where the level of the received digital modulation wave 101 is constant.;COPYRIGHT: (C)1994,JPO&Japio