| 摘要 |
PURPOSE:To improve the measuring accuracy of the fading frequency by calculating the frequency from the reciprocal of the mean value of the time when the reception level is lower than a set level. CONSTITUTION:The center instantaneous value set at a reception level input terminal 11 is detected by a detecting circuit 12, and the value having the prescribed relation with the center instantaneous value is set by a level setting circuit 13. That is, a level that is relatively constant to the instantaneous value obtained by excluding the fluctuation component of the center value can be supplied to the circuit 13. The circuit 13 compares the instantaneous value of the set level with that of the reception level. If the latter level is lower than the former level, the circuit 13 opens a gate circuit 15 to transmit the sampling clock supplied through a clock input terminal 18 as a detected pulse. A counter 16 counts the detected pulses supplied from the circuit 15 and sends them to an arithmetic processing circuit 17 to calculate the mean value of the time when the instantaneous value of the reception level is lower than that of the set value. Then the counter 16 calculates the fading frequency from the reciprocal of the calculated mean value and outputs the frequency through a fading output terminal 19. Thus the fading frequency is detected and the measuring accuracy of the frequency is improved. |
