| 摘要 |
<p>In an automatic gain control device which is connected to an output circuit (21, 22) supplied with a gain controlled signal to produce a timing signal in a receiver of a direct conversion type and which includes an amplifier (23, 24) for amplifying a received baseband signal into an amplified signal with a controllable gain, a d.c. blocking circuit (25, 26) for producing a variable level signal with the amplified signal exempted from a d.c. component, and a level detector (27, 28) for producing a level value signal by detecting level values of the variable level signal, a timing controller (31) is supplied with the timing signal to produce a first control signal in each of predetermined time slots in which a receiver input signal comprises bursts representative of an information signal. A second control signal is produced in an interval between two consecutive ones of the predetermined time slots. Controlled by the first control signal, a sample holding circuit (35, 36) supplies the level value signal to the amplifier to control the gain. Controlled by the second control signal, a clamping switch (33, 34) produces the gain controlled signal by removing a d.c. offset from the variable level signal. The receiver input signal may be orthogonally modulated.</p> |
