Circuit for generating system carrier signals, line pilot frequencies, channel carrier and control frequencies in a telephone equipment with multichannel overhead lines

摘要

A circuit arrangement for producing system carriers and linear pilot frequencies of multi-channel carrier-current overhead telephone lines, which consists of a single oscillator, to the output of which is connected a combination of frequency dividers, filters connected to the output of the frequency dividers, as well as filters connected to the outputs of modulators or frequency dividers linked to the output of the filter, whereby the outputs of the individual frequency dividers are connected directly or via filters to channel-carrier control frequency outputs or to system carrier or lower-band pilot frequency outputs. The essence of the invention is that the combinations of frequency dividers are connected in a switchable manner to the circuits which produce the upper-band system carrier frequencies (FB1...FB4) and are permanently connected to the circuits which produce the upper-band pilot frequencies (PB1, PB2); that the circuits which produce the system carrier frequencies (FB1...FB4) consist of a series-connected circuit comprising a filter (SZ4), a modulator (M2), a further filter (SZ5) and a frequency divider (D11) with a division ratio of 2:1, whereas a series-connected circuit producing an upper-band pilot frequency (PB1) is provided with a filter (SZ6), a modulator (M3) and another filter (SZ7), whereas a series-connected circuit producing the other upper-band pilot frequency (PB2) consists of a filter (SZ8), a modulator (M4) and a further filter (SZ9).