| 摘要 |
Feeding metering pulses to subscriber lines for telecommunications terminals is to be carried out without interference, without requiring inductances or winding materials. The circuit arrangement is to be designed in such a manner that its components can be combined in integrated circuits. The connecting pulse for sending a metering pulse is shaped by an RC low-pass filter to form an annular curve which rises and falls in accordance with an e function. The connecting pulse thus shaped is linked to the frequency of the metering pulse by means of an amplitude modulator. At the output of the amplitude modulator, a low-pass filter is connected which blocks all harmonics present in a square wave oscillation. A subsequent analog adder is used to superimpose the then sinusoidal signal of the metering pulse on the analog audio-frequency information signal. <IMAGE> |
