Abstract: Optoelectrical conversion of the received optical service signal (OSS), bandpass filtering and subsequent squaring produce a spectral line at the clock frequency (fT). This clock line (TL) is selected by means of narrowband filtering and rectified. The service signal voltage (VTLM) obtained in this manner is used to switch on a Raman pump laser (11).

Abstract: The invention relates to a method for detecting a check-back signal in a transmission system for optical signals. According to said method, a constant proportion of the output in a defined frequency range of the check-back signal is concentrated in a narrow-band spectral range and is determined after a transmission phase by means of a narrow-band detection of the concentrated energy around the spectral range. If no signal is identified during the narrow-band detection, a line interruption is determined and no pump source is switched on for safety reasons. The narrow-band detection of the check-back signal also allows the transmission attenuation of the transmission system to be measured.

Abstract: Optoelectrical conversion of the received optical service signal (OSS), bandpass filtering and subsequent squaring produce a spectral line at the clock frequency (fT). This clock line (TL) is selected by means of narrowband filtering and rectified. The service signal voltage (VTLM) obtained in this manner is used to switch on a Raman pump laser (11).

Abstract: A phase-locked loop for controlling the phase of an output signal S2 dependent on a reference signal S1 with only a small phase timing error has a sampling circuit for sampling the reference signal S1 with the output signal S2 and for generating a sampling signal S1A, a jitter modulation circuit (3) for generating a sampling signal S1AJ delayed by a defined time duration and for alternating output of the undelayed sampling signal S1A and the delayed sampling signal S1AJ, a phase detector for acquiring an average phase difference between the output signal S2 and the delayed and undelayed sampling signals S1A and S1AJ, and a controllable oscillator for generating the output signal S2 with a frequency that is controllable dependent on the average phase difference acquired by the phase detector.

Abstract: A remote fed intermediate regenerator for use in transmission lines for digital signals having no direct current component has for each transmission direction a series circuit including a distortion corrector a regenerator circuit and a transmitting amplifier. For isolating the signal path and the remote feed path each intermediate regenerator is preceded and followed by remote feed dividing filters and each intermediate regenerator contains a high power Zener diode bridging the remote feed path of the regenerator and the distortion correcter and regenerator circuit each contain low power Zener diodes for stabilizing the operating voltages thereof. A transmitting amplifier for the intermediate regenerator has dynamic current characteristics and operates to stabilize the voltage without the necessity of a Zener diode and accordingly does not require a high-value input impedance thereby avoiding a significant power loss.