| 摘要 |
PURPOSE:To increase the equalizing ability in a simple circuit, by extracting 3 pilot signals from a signal itself by the use of LPF and HPF from the reception spectrum and controlling the amplitude variable circuit during transmission line through the comparison of the three signals. CONSTITUTION:The low-and high-band sides of a reception power spectrum in a radio digital system are respectively extracted at an LPH and an HPF, they are detected at detectors DL, DH to obtain the pilot signals PL, PH. Further, at the middle of band, a pilot signal Po is detected at a detector Do via an attenuator AT as it is. The signals PL, Po, PH are inputted to a control circuit 2, where the difference between the PL, PH is detected for processing to obtain the control signal VF, and a control signal VQ is obtained by detecting the difference between the Po and the PL, PH which are greater for processing. The signal VF controls a variable resonance circuit 11 in the transmission line, and the high-band low-band characteristic of the output signal spectrum is made to a given form. Further, the signal VQ controls the circuit 11 so that the part fallen down the band of the output spectrum can be made flat. |
