| 摘要 |
PURPOSE:To improve the reliability of a system by using a signal branched from a main line so as to eliminate a disturbing wave thereby obtaining the erasure effect while following the wave even if the level and phase of the disturbing wave are fluctuated and improving the stability with simple constitution. CONSTITUTION:The stability of an oscillation frequency of the 1st local oscillator 3 of a TV repeater is kept to nearly 1.5X10<-7> or below, the signal is converted into an IF signal by a frequency converter 2 and fed to a frequency stabilizing section 4 constituting a disturbing wave eliminating circuit. The frequency stabilization of a desired wave signal and the disturbing wave signal at the IF band is attained by using a distributor 5, a BPF 6, a discriminator 7 and a squelch circuit 8 of the stabilizing section 4 an the desired wave and the disturbing wave signal are fed to a disturbing wave elimination section 10. The IF signal stabilized by the distributor 11 of the elimination section 10 is branched into two, the disturbing wave of the IF band is extracted by the BPF 18 of once circuit and fed to a synthesizer 15. Then the result is synthesized with the IF signal whose phase and level are adjusted by a variable amplifier 12 and an attenuator 13 to eliminate effectively the disturbing wave.
|
