Abstract: A data terminal is able to use data services of a cellular network so that it is detachably connected to a mobile phone with a connection cable. The data services need not be supported by the telephone. The connection cable forms a fast synchronous serial bus. The service-specific data protocols needed in implementing a data service are accomplished in a microprocessor unit in an external interface adaptor connected to one end of the serial bus, said processor being via the bus directly connected to the processor performing the signalling and control functions and the channel coder of the phone. Thus, the interface adaptor is able to exchange messages directly with the processor unit and the channel coder of the phone.

Abstract: Disclosed is a method and a device for compensating the DC offset (dU) of a D/A converter (2), particularly in the base frequency modulator of a mobile phone. The method and the device use an error correction register (5), whose value is changed on the basis of the DC offset, and which is added to each signal sample to be converted for compensating the DC offset. The value of the error correction register (5) is changed in a testing mode so that a preset control value is fed into the D/A converter (2), corresponding to the zero voltage of the output of an ideal D/A converter; the voltage values of outputs of a differential output pair (2a, 2b) arranged in connection with the D/A converter (2) are compared to verify the polarity of the voltage difference (dU) of the outputs and the polarity, i.e.

Abstract: A computer controlled apparatus includes a program counter for manifesting program count values and a processor for executing a prestored program in accordance with the program count values. The apparatus includes a read only memory with a prestored program that is accessible in response to generation of a span of program count values. Auxiliary memory includes a prestored program segment. A control circuit is coupled to the program counter and stores a predetermined program count value within the span of program count values in ROM. The control circuit is responsive to a match of a program count value from the program counter and the determined program count value to cause the program counter to be loaded with a branch program count value. That value enables the processor to immediately access and execute the prestored program segment from the auxiliary memory in lieu of a subspan of program count addresses in the ROM.

Abstract: The invention provides an improved method and apparatus for identifying a bad GSM speech frame. Both the estimated signal-to-noise ratio (ESNR) of the received signal and the pseudo bit error rate (PBER) of a recorded speech signal are used to determine whether or not a speech frame is bad.

Abstract: Speech coding of the code excited linear predictive type is implemented by providing an excitation vector which comprises a set of a pre-determined number of pulse patterns from a codebook of P pulse patterns, which have a selected orientation and a pre-determined delay with respect to the starting point of the excitation vector. This requires modest computational power and a small memory space, which allows it to be implemented in one signal processor.