FREQUENCY CHARACTERISTIC MEASURING METHOD FOR TRANSMISSION LINE IN COMMUNITY ANTENNA TELEVISION SYSTEM

摘要

PURPOSE:To attain the measurement of the frequency characteristic of a transmission line over the entire transmission band by transmitting a measuring signal to the transmission line for a CATV system and using a white noise as the measuring signal. CONSTITUTION:A measuring signal source 7 generating the white noise is mouted on the side of the head end 5 of a main line 1. Besides, a spectrum analyzer for measuring the white noise 10 is mounted in the middle of the main line 1. The head end 5 broadcasts in the frequency band of the frequency 73 to 451.25MHz. The measuring signal source 7 is composed of a noise generator 8 and an amplifier 9 so as to generate the white noize of the frequency 73 to 451.25MHz by the noise generator 8 and to simultaneously amplify it into a level which can be measured by the spectrum analyzer 10 by the amplifier 9 to output it to the main line 1. Thus, the white noise of a uniform level is used as the measuring signal without regard to the frequency so that the frequency characeristic of the transmission line can be measured over the entire frequency band.