Abstract: Self-clocked two-level differential signaling methods and apparatus assuring both clock synchronization and ease of recovery of transmitted data. In accordance with the method, the data is encoded differentially on a differential signal that changes polarity at the end of each bit time. This allows clock recovery at the receiver simply by detection of the polarity change. The data is encoded, bit by bit, as exceeding a predetermined magnitude for a bit of a given state and as not exceeding the predetermined magnitude for the opposite state. Consequently data recovery is by way of a simple signal magnitude detection during a bit time, such as by a detection of signal magnitude a predetermined time. The apparatus does not require a phase locked loop in the receiver, thereby saving power and time to obtain synchronization. The method is conducive to varying bit time or duration, thereby reducing the peaks in the EMI radiation.