Abstract: A digital serial interface connects a transmitting device with a receiving device for communicating both data bits and synchronization signals via the serial interface. The transmitting device include a primary transmitter for converting a serial sequence of the data bits into successive data signal levels, and further includes a secondary transmitter for converting synchronization signals into synchronization signal levels different from the levels employed for the data signals. The receiving device has a primary receiver for the data signal levels for converting a sequence of data signal levels into a serial sequence of data bits, and further includes a secondary receiver fir the synchronization signal levels for converting synchronization signal levels into synchronization signals.

Abstract: For establishing a local communication connection between a terminal (102) of a cellular radio system and an accessory device (103), a radio channel is identified (301, 302) on which there is no perceivable radio traffic in the cellular radio system, and a communication connection is established (303, 501) between the terminal and the accessory device on the identified radio channel. The radio channel is preferably a code channel of a CDMA system.

Abstract: Some mobile station cellular networks use either amplitude modulation or constant envelope modulation depending on the situation. The pulsed transmitter of the mobile station is switched on and off by a first control signal (TXP) and the output power envelope shaping of the pulse to be transmitted is controlled in the feedback loop by a second control signal (TXC). According to the invention the output power is controlled by a third control signal (TXCE) which in the amplitude modulation case switches off the feedback loop for the period of the information transfer and which at other times closes the feedback loop.

Abstract: The frame timing control of TDMA signals in cellular systems is implemented in mobile stations and/or base stations according to the invention so that the functions are divided between the frame timing control unit (1) and the microcontroller (2). In this way, the frame timing can be controlled in a flexible manner, for instance when moving from one TDMA cell type to another, without breaking the speech or data communication.