Abstract: A circuit for detecting and verifying a presence of a terminating device for a high speed data transmission line. The circuit contains a first cable detector which generates a first signal if a first cable is present. A second cable detector generates a second signal if a second cable is present. The terminating device is contained in a plurality of resistor packs, each of the which contains an extra resistor. A terminating device detector senses the extra resistor presence, thereby detecting the presence of the resistor packs. The terminating device detector generates an ALL-EQUIPPED signal and a NON-EQUIPPED signal, the ALL-EQUIPPED signal is generated when all of the plurality of resistor packs are present, the NON-EQUIPPED signal is generated when all of the plurality of resistor packs are absent. Finally, a verifier circuit receives the first signal, the second signal, the ALL-EQUIPPED signal and the NON-EQUIPPED signal.

Abstract: A telecommunication system comprising a bus conductor to which respective stations are connected by respective transformers, communication taking place via voltage pulses V.sub.p on the bus. Each voltage pulse V.sub.p causes a magnetizing current i.sub.m to be developed in the spurious self-inductance of each connected transformer, which if not compensated will cause a faulty voltage to arise after termination of the pulse and so result in faulty information transfer. The invention provides a controllable voltage source which generates a compensating current i.sub.c in the winding of each connected transformer to compensate this faulty voltage, so that at the instants of pulse termination the total magnetization of all transformers remains unchanged.

Abstract: A regenerator 10 is provided with a tuning recovery facility 15 which has a multiple passband capability. The regenerator can operate with several line bit rates each corresponding to one of the passbands.

Abstract: An equalizer arrangement comprises a fixed-characteristic equalizer which is supplemented by a variable-amplitude notch equalizer to enable proper equalization of signals transmitted via cables of arbitrarily mixed cable gauges. Automatic control of the notch amplitude is provided by detecting a predetermined signal level in the equalized signal, comparing this with its correct value, and controlling an up/down counter accordingly. The count of the counter determines a current flow through a diode which constitutes a variable resistance of the equalizer.

Abstract: Circuit arrangement for the automatic, adaptive, temporal distortion correction of the ringings of a multi-stage base band signal comprises a controlled-gain amplifier to which the distorted base band signal is supplied. A correction signal device generates a correction signal, and a summer generates the distortion corrected base band signal by adding of the correction signal and the signal emitted by the controlled-gain amplifier. The distortion corrected base band signal is supplied to a sample-and-hold circuit and its output signal, after rectification and smoothing, is compared to a reference value signal. The level of the distorted base band signal is controlled with the output signal of the comparator with the assistance of the controlled-gain amplifier.

Abstract: An equalizer circuit arrangement is provided for use without readjustment for a wide range of transmission line lengths. The circuit (10) is comprised of a resistor (20) and a capacitor (22) which introduce an additional time constant delay into the transmission system in order to reduce the percentage change of the transmission line response time for the shortest line used as compared to the longest line employed. This reduction permits one equalizer to be designed and used for the complete range of transmission line lengths involved.

Abstract: Attenuation equalizer for correcting within a frequency range the temperature and frequency-depending attenuation variation of cables, comprising a cascade arrangement of a fixed and a variable attenuation correction circuit, connected to a control circuit, the variable attenuation correction circuit comprising a bridge-T network having a series arrangement, of two identical series resistors bridged by a variable bridging impedance and a parallel impedance connected between these two series resistors, the fixed attenuation correction circuit having a lower attenuation for higher frequencies than for lower frequencies, the temperature dependency of the cable being eliminated in the variable attenuation correction circuit and the frequency dependence being eliminated mainly in the fixed attenuation correction circuit for which purpose the variable attenuation correction circuit comprises only two adjustable components.

Abstract: A circuit for unilaterally scanning teletype characters wherein the characters are supplied to an integrating circuit and to an impulse circuit wherein the impulse circuit can be controlled by the step changes of a character. A comparator circuit receives the output of the integration circuit and assumes a definite condition with each step change through a switch which is controlled by the impulses of the impulse circuit and a reference signal is supplied to the comparator circuit and the reference signal can be adjusted according to the desired delay of the descending or ascending edge of the step changes in the characters.

Abstract: A transmission line having a fixed characteristic impedance, e.g., 600 ohms, is coupled to a receiver through an input transformer working into a very small impedance, e.g., 10 ohms or less. As compared to a conventional arrangement, where an input transformer works into a load nearly as high as the characteristic impedance of the line, the new arrangement has considerably better low frequency response and delay distortion characteristics. The new arrangement permits a much smaller transformer to be used if desired while retaining favorable low frequency response and delay distortion characteristics.

Abstract: A system equalizer and a method of equalization employed in a repeatered submarine cable system, in which automatic gain controlled (AGC) submerged repeaters are employed to compensate for fluctuations of the cable loss caused by the temperature fluctuations in the surrounding environment of the repeatered submarine cable system. In a terminal equipment connected to the repeatered submarine cable system, the seasonal misalignment of the repeatered cable system is equalized by a switchable equalizer having a loss-frequency characteristic corresponding to the total of compensation errors in the AGC submerged repeaters. Short-term level fluctuations of the repeatered cable system are compensated by an automatic equalizer, which has a loss-frequency characteristic proportional to the square root of frequency f and is controlled by the level of a pilot signal transmitted through the repeatered submarine cable system. An unknown fixed deviation is finally equalized by a second adjustable equalizer.

Abstract: In a long line data acquisition system, an input network is provided for coupling the lines to a data acquisition unit. The network includes the cascade combination of a first filter presenting a low pass frequency response to common mode voltage and a second filter presenting a low pass frequency response to difference mode voltage. The output of the second filter is coupled to an amplifier having high common mode rejection. The network substantially reduces, at the amplifier input, both common mode and difference mode noise picked up by the lines.