| 摘要 |
PURPOSE:To obtain a simple constituted and economical carrier wave detecting means, by decoding signals obtained by converting FSK modulated waves into PCM codes. CONSTITUTION:Information converted into 8-bit PCM codes is sent to a register 2 from a digital network 1. A NAND gate 3 is for detecting PCM codes above a specified level in the register 2, and its output is stored in a flip flop 4. The output of the flip flop 4 is inputted into an exclusive-OR cirit 5 and the output of the circuit 5 is used for controlling the operating condition of a counter 6. The circuit composed of the exclusive-OR circuit 5 and the counter 6 is for outputting a carrier wave detection signal CD ''1'' to the output of the counter 6 when PCM codes above a prescribed level are continued for more than a prescribed period. This means that the carrier wave detecting signal CD is turned to ''0'' only when PCM codes below a prescribed level are continued for a prescribed period. |
