Method for increasing the signal-to-noise ratio for common-mode interference on a two-wire data bus

Abstract

Data transmission method for a two-wire data bus from a transmitter having ports to a receiver having ports. The method comprises the steps of: detecting a first common-mode voltage swing on the ports and forming a first common-mode signal. Detecting a second common-mode voltage swing on the ports and forming a second common-mode signal. The transmitter sending data via the two-wire data bus. The receiver receiving the data. The voltage difference on the ports being compared with a lower and an upper reception threshold, wherein an output of an apparatus element assumes a first or second level on the basis of this comparison. Raising the differential send level if the absolute value of the first common-mode signal is greater than a first threshold value. Raising the upper reception threshold and/or lowering the lower reception threshold if the absolute value of the second common-mode signal is greater than a second threshold value. The method allows the transmission of a datum from the transmitter to the receiver. On the basis of the result of the comparison of the absolute value of the detected first common-mode signal with a first threshold value, the upper reception threshold is raised and/or the lower reception threshold is lowered whenever this absolute value of the first common-mode signal is greater than this first threshold value.