Narrowband transmission method for a digital mobile radio system

The invention relates to a narrowband transmission method for a digital mobile radio system for communication of mobile subscriber stations with one another and with fixed stations. For this purpose, a reduction in the transmission power for the mobile radio units is intended to be enabled while maintaining the range, while improved resistance to adjacent signal interference and increased immunity to common-channel interference are intended to be achieved. For this purpose, the invention provides that the coded data stream is combined to form symbol blocks of n bits with a resulting symbol rate which is lower than the bit rate by a factor n. Each of the 2 symbols required to represent a continuous data stream is transmitted on the radio path as a word with 2 chips and the 2-fold chip rate in such a way that a Barker code roughly corresponding to the word length is placed in front of a block formed from a plurality of words and is transmitted. At the receiving end, the Barker code is correlated by a correlator with high resolution capacity in order to obtain a time signal for the correlative evaluation of the chip words. The symbols retrieved in this way are then converted back into the continuous data stream of the original bit rate.