| 摘要 |
<p>PURPOSE:To maintain the suppression degree to a certain extent despite a low level of reference signal power and at the same time to increase the allowance range of the reference signal power so that a correlation loop has no oscillation, by controlling the equivalent gain of the correlation loop in response to the value of the reference signal power. CONSTITUTION:Attenuators 6 and 7 having different attenuation degrees a1 and a2 are provided together with a selection switch 8 which is controlled by the signal of a comparator 10 and a mixer 9. The output signal of the mixer 9 is equal to the reference signal power ¦x¦<2>. The comparator 10 compares the power ¦x¦<2> with values p1 and p2 which are previously set. Then the switch 8 selects terminals S1-S3, respectively. As a result, the equivalent gains ranging from an amplifier 4 to the output terminal of the switch 8 are set at g, a1g and a2g. Thus the gain of a correlation loop is controlled in response to the power ¦x¦<2>. In addition, this gain has such characteristics as shown in the figure by setting properly the attenuation degrees a1 and a2. In such a way of deciding the attenuation degree, the allowance range can be increased for the power ¦x¦<2> so that the correlation loop has no oscillation.</p> |
