Circuit arrangement for generating charge pulses

An interface unit circuit arrangement for controlling a voltage level of charge pulses during digital telecommunications, the interface unit including

• at leach one analog interface connected to a subscriber telephone by an electric service line,
• a digital interface connected to a central exchange by cables, and a generating circuit for producing the charges pulses as a function of signals transmitted by the exchange, the charge pulses being trarsmitted to a respective subscriber telephone, the circuit arrangement comprising:
• means for measuring a service line voltage across the service line associated with the respective subscriber telephone when loop current flows through an electric circuit of the respective subscriber Telephone, said service line voltage being derived from a required supply voltage of a power source connected to the service line and said service line voltage being proportional to a length of the service line, and
• means responsive to said service line voltage, for adjusting the voltage level of the charge pulses produced by the generating circuit.