MODEM WITH IMPROVED RECEIVE POWER FOR CONNECTION TO A TWO-WIRE CURRENT LOOP AND MEASURING TRANSDUCER, POSITION CONTROLLER AND INPUT AND OUTPUT UNIT COMPRISING SAID MODEM

摘要

A receiving circuit (1) is adapted to receive a frequency shift keyed input signal (ES) having a desired pulse duty factor. The receiving circuit comprises a high-pass filter (12) at the input side for decoupling the steady component of the input signal (UE) and for producing a filtered signal (FS), a downstream amplifier (16) and a downstream comparator (13) for producing a digital output signal (AS). The invention is characterized in that the receiving circuit (1) comprises an integrator (30) to which the digital output signal (AS) is supplied on the input side and which makes a correction signal (KS) available on the output side. The correction signal (KS) is retransmitted to the amplifier (16) for adjusting a steady component of the filtered signal (FS) to adjust deviations of the duty factor of the digital output signal (AS) from the desired duty factor.