| 摘要 |
PURPOSE:To reduce a generation of a bit error of a demodulation data by limiting a change of a frequency of a regenerating carrier wave even if the change of the frequency is produced in a local oscillating circuit used for fre quency conversion. CONSTITUTION:An input frequency fo of a carrier wave regenerating means 30 is not influenced by an output frequency change of a voltage control type oscillator 21 constituting a second frequency conversion circuit 20 but only depends on a coming signal inputted to input terminals I, N. Therefore, an oscillator constituting the second frequency conversion device 20 can stabilize an input fre- quency of the carrier wave regenerating circuit 30 without constitut ing by a crystal oscillator excellent in accuracy. An internal loss of a system is prevented to be increased by two types of feed back loops of a first feed back loop comprising a first frequency conversion circuit 10, the second fre quency conversion circuit 20, the carrier wave regenerating circuit 30 a PLL circuit 50 returning to the frequency conversion circuit 10 and a second feed back loop formed by the second frequency conversion circuit 20, the carrier wave regenerating circuit 30, a PLL circuit 40 and returning to the second frequency conversion circuit 20. |
