A device (20, 30, 40, 60, 70, 80), comprising: an interface circuit (200, 300, 400, 600, 700, 800) configured to interface the device with a line-pair, wherein the interface circuit comprises: a diode bridge having polarity-independent input terminals coupled to the line-pair, and further having a positive output terminal and a negative output terminal; a voltage-controlled variable resistance element (260, 360, 460) connected across the positive and negative output terminals of the diode bridge; a galvanic isolation device (230, 330) having an input and an output which are galvanically isolated from each other, the galvanic isolation device being configured to receive a transmit signal at the input and to couple the transmit signal at the output; and a first filter (240, 340, 440, 840) having an input configured to receive the transmit signal via the galvanic isolation device and having an output connected to a control terminal of the voltage-controlled variable resistance element, wherein the first filter includes decoupled charge and discharge paths so as to decouple a rise time of the transmit signal from a fall time of the transmit signal, wherein the voltage-controlled variable resistance element is configured to couple the transmit signal to the line-pair via the diode bridge; characterised in that the device further comprises: a variable edge delay circuit (270, 370, 572, 574, 576), wherein the variable edge delay circuit is configured to compensate for duty cycle asymmetry introduced into the transmit signal by other elements of the interface circuit by delaying rising edges of the transmit signal substantially more than falling edges of the transmit signal, or delaying falling edges of the transmit signal substantially more than rising edges of the transmit signal, and wherein the galvanic isolation device (230, 330) is adapted to receive the transmit signal via the variable edge delay circuit. an interface circuit (200, 300, 400, 600, 700, 800) configured to interface the device with a line-pair, wherein the interface circuit comprises: a diode bridge having polarity-independent input terminals coupled to the line-pair, and further having a positive output terminal and a negative output terminal; a voltage-controlled variable resistance element (260, 360, 460) connected across the positive and negative output terminals of the diode bridge; a galvanic isolation device (230, 330) having an input and an output which are galvanically isolated from each other, the galvanic isolation device being configured to receive a transmit signal at the input and to couple the transmit signal at the output; and a first filter (240, 340, 440, 840) having an input configured to receive the transmit signal via the galvanic isolation device and having an output connected to a control terminal of the voltage-controlled variable resistance element, wherein the first filter includes decoupled charge and discharge paths so as to decouple a rise time of the transmit signal from a fall time of the transmit signal, wherein the voltage-controlled variable resistance element is configured to couple the transmit signal to the line-pair via the diode bridge; characterised in that the device further comprises: a variable edge delay circuit (270, 370, 572, 574, 576), wherein the variable edge delay circuit is configured to compensate for duty cycle asymmetry introduced into the transmit signal by other elements of the interface circuit by delaying rising edges of the transmit signal substantially more than falling edges of the transmit signal, or delaying falling edges of the transmit signal substantially more than rising edges of the transmit signal, and wherein the galvanic isolation device (230, 330) is adapted to receive the transmit signal via the variable edge delay circuit. a diode bridge having polarity-independent input terminals coupled to the line-pair, and further having a positive output terminal and a negative output terminal; a voltage-controlled variable resistance element (260, 360, 460) connected across the positive and negative output terminals of the diode bridge; a galvanic isolation device (230, 330) having an input and an output which are galvanically isolated from each other, the galvanic isolation device being configured to receive a transmit signal at the input and to couple the transmit signal at the output; and a first filter (240, 340, 440, 840) having an input configured to receive the transmit signal via the galvanic isolation device and having an output connected to a control terminal of the voltage-controlled variable resistance element, wherein the first filter includes decoupled charge and discharge paths so as to decouple a rise time of the transmit signal from a fall time of the transmit signal,