Abstract: A cellular mobile radio system comprises cells divided into P sectors each having its own timebase. The system uses time division multiple access and accordingly transmission is effected in bursts each transmitted during a time slot, or channel time slot, of predetermined rank relative to a reference of the timebase of the sector concerned. N time slots form a frame which repeats periodically. A control channel is reserved for each sector for transmitting signalling and control data, a different control channel being associated with each sector. The timebase of each sector is shifted a predetermined number of time slots relative to the timebases of the other sectors of the same cell. The offsets are such that the control channels relating to each sector are conveyed at different times.

Abstract: A method of calibrating a radio receiver (100) which has a desired IF center frequency (fo) includes generating and applying to the receiver's demodulator (126) a plurality of reference signals. The demodulated reference signals are used to generate, for the demodulator, a transfer function that is predictive of amplitude versus frequency characteristics of signals to be demodulated by the demodulator (126). The transfer function (202) is used to determine a frequency offset between a received signal's intermediate frequency and the desired frequency fo. The determined frequency offset is used to adjust the IF frequency of the received signal towards the desired frequency fo. The adjustment process preferably continues until the frequency offset is below a desired threshold. A receiver using the disclosed method is also described.