| 摘要 |
PURPOSE:To implement AGC based on the output of a correlation device immune to a disturbing wave by providing a means sampling a peak level of a correlation output for a burst period and holding the peak value for a multiplex modulation period so as to conduct accurate gain control with simple configuration. CONSTITUTION:A signal received from an antenna 1 is amplified by an RFAMP 2, and fed to a correlation device 7 to be a input to a next stage through a variable attenuator 3. The correlation device 7 provides an output in correlation with a reference spread signal and the output is a signal with an envelope synchronously with a clock sent from a transmitter, then an envelope detector 6 detects the envelope. The signal is given to a peak hold circuit 5, in which a prescribed signal is obtained. The level during a burst period is in proportion to an input signal level. On the other hand, a burst detection circuit 8 detects a time for the burst period to control a sample-and-hold circuit 4. Thus, a signal holding the level for a burst period is outputted from the circuit 4 to decide the attenuation of the attenuator 3. |
