Nokia Mobile Phones Limited

Seppo E Lamberg

Harri A Jokinen

Harri Honkasalo

Zhi Chun Honkasalo

A method is disclosed of demodulating a signal (20) modulated by differential quadrature phase shift keying so that two bits of information are coded into each symbol period. The method comprises using a high frequency clock to determine the time taken (t.sub.1, t.sub.2, t.sub.3, t.sub.4), for the modulated signal to execute a predetermined number of cycles, such as 21, in the symbol period (T) and comparing the time thereby determined with the time (t.sub.o) of execution of the predetermined number of cycles for an unmodulated signal.

Demodulation of digital phase modulated signal

In a radio-telephone system based on time-division multiple access, the AGC function of the receiver can be controlled so as to be approximating the actual value at the beginning of the reception timeslot. The field strength of a specific signal transmitted by a base station during a timeslot preceding a concerned reception timeslot is measured, the specific signal having a power the ratio of which to the power of the concerned signal is presumed. On the basis of this measured field strength and the presumed ratio, the required AGC gain of the AGC amplifiers is calculated and the AGC gain is set according to the calculated gain for the time of the concerned reception timeslot.

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Salo, Finland

Seppo E Lamberg