| 摘要 |
PURPOSE:To detect carriers with high accuracy by using an increase signal comparator which compares the output signal of a delay circuit with the signal increased by a signal increasing means and a decrease signal comparator which compares the output signal of the delay circuit with the signal decreased by the signal increasing device. CONSTITUTION:The output of a delay circuit 14 is amplified by an amplifier AMP5 by +3dB and undergoes division of voltage through resistances 45, r6 and r7. Then the voltage of the junction between resistances r6 and r7 is supplied to the reference point of the amplifier AMP5. Thus the junction between resistances r6 and r5 is decreased by -3dB. A level detecting circuit 13 consists of a comparator CMP1 and resistances r8, r9, etc. The detection level of the circuit 13 is obtained by dividing the voltage +V by resistances r8 and r9. an AND circuit 19 obtains an OR between the output G of the circuit 13 and outputs H and I of comparator 17 and 18 respectively. Thus a carrier detection signal J can be delivered. |
