AUTOMATIC TELEPHONE SYSTEM PROVEDED WITH MEANS OF PROTECTION AGAINST UNINTENTIONAL INTERRUPTIONS DURING REGISTER SIGNALLING

摘要

Automatic telephone system provided with means of protection against unintentional interruptions during register signaling, comprising a telephone station in which a signaling equipment is arranged to receive a tone code signal from a second telephone station via an incoming channel in a telephone connection between the telephone stations and to transmit a return signal to the second telephone station via an outgoing channel in the telephone connection to stop the transmission of the tone code signal, the signaling equipment comprising a receiver device which has a signal input connected to the incoming channel and an output arranged to feed out the information content of the tone code signal, a transmitter device which has an activation input and a signal output which latter is connected to the outgoing channel for transmission of the return signal independence on that the transmitter device is activated via the activation input, a register device which has an activation input and a write input which latter is connected to the output of the receiver device for registration of the information content of the to now code signal when the register device is activated via its activation input, and a control device which has an input connected to the output of the receiver device and an output connected to the activation inputs of the transmitter device and the register device and arranged to be activated in dependence on that the tone code signal is received and which comprises a first delay means for inhibiting after each activation of the output of the control device a continued activation of the output of the control device a continued activation of this during a predetermined first time interval within which the receiver device normally as a consequence of signal delays between and in the telephone stations, continues to receive the tone code signal, characterized in that the control device comprises a second and a third delay means which have a respective output and are arranged to be activated after each activation of the output of the control device during a predetermined second time interval of a shorter duration than said first time interval and the during a predetermined third time interval of a longer duration than the sum of said first time interval and duration of the return signal, respectively, and a memory means which has an activation input connected to the output of the second delay means, a set input gated by the last-mentioned activation input and connected to the input of the control device and a reset input connected to the output of the third delay means to be set by an interruption in the tone code signal during said second time interval when the second delay means is activated and to be reset when said third time interval has elapsed and the activation of third delay means ceases and which in its set condition is arranged to inhibit that the output of the control device is activated.