Ericsson Ge Mobile Communications Inc.

Ericsson Ge Mobile Communications Holding Inc.

Karl B Lindell

The invention relates to a method and to an arrangement for demodulating a signal (f) preferably frequency modulated with digital information, and then particularly a frequency shift modulated signal, with a frequency counter detector (16) which directly produces a digital value representative of the instantaneous frequency of the frequency modulated signal. In order to obtain the lowest possible uncertainty in frequency detection at unchanged counter frequencies (f.sub.r), the frequency modulated signal is mixed down to a difference frequency (f.sub.3) which is insignificantly higher than the sampling frequency (f.sub.s) required to extract the modulation information from the instantaneous counter value (N.sub.2) The frequency counter detector begins a counting sequence during each of the periods of the difference frequency.

Method and arrangement for demodulating a frequency modulated signal

The frequency stability of the signals transmitted by a plurality of mobile stations to an associated base station within a radio network is supervised by first generating a reference signal at the base station. The signals received from the mobile stations are compared to the reference signal and a difference signal is generated. The difference signal is compared to first and second error values and if the difference exceeds the first error value, the mobile is summoned for a service adjustment. If the difference exceeds the second error value, the mobile is disabled from further transmissions.

Digital radio mobile frequency supervision

A system for adjusting the frequency of transmissions between a base station and a mobile station. The mobile station detects the frequency of the signal received from the base station, determines whether the signal was received from the current base station and adjusts the output signal of a local crystal-controlled reference oscillator in accordance with the difference between the frequency of the output signal and the frequency of the received signal.

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Lidingo, Sweden

Karl B Lindell