GB1142712A - Improvements in and relating to two-wire segregated carrier frequency band transmission systems with monitored intermediate amplifiers - Google Patents

Abstract

1,142,712. Frequency multiplex systems. FELTEN & GUILLEAUME CARLSWERK A.G. 23 March, 1966 [9 July, 1965], No. 12808/66. Heading H4R. In a two wire carrier frequency transmission system in which transmission takes place in one direction in one frequency band and in the other direction in a second frequency band and in which each band comprises a number of groups of speech channels and in which facilities are provided for monitoring the performance of the intermediate repeater stations from either terminal station by transmitting a signal frequency or frequencies in the " go " transmission band from the terminal station to a repeater which translates the frequency, or frequencies, e.g. by frequency doubling or intermodulation, to a frequency in the transmission band for the return direction to be monitored at the terminal station, has the frequency gap R between the go and the return bands arranged to be such that f 1 + n(F + a)# R#f 1 +n(F+a)+a where f 1 = the lowest frequency of the lowest channel, F = the width of each group of channels, and a = the frequency gap between adjacent groups in the band and n is any low whole number. In addition the lowest frequency may be selected to be p(F + a) where p = any low whole number. The arrangement allows monitoring signals arranged in specified parts of the transmission band between groups in one direction of transmission to be returned after translation in a repeater in the other band in the gaps between groups of speech channels.