Nokia-mobira Oy

Matti Ylivakeri

A method and circuit for automatically controlling the frequency of a radio telephone. According to this method, the frequency of the signal detected at the receiver of a radio telephone is mixed with the output frequency of a phase-locked loop in a first mixer. The output frequency of the first mixer is mixed in a second mixer with the frequency derived from a local oscillator. The frequency of the phase-locked loop is controlled on the basis of the frequency deviation of the output frequency of the second mixer. This frequency deviation can be determined by counting the pulses generated by the second mixer during a predetermined time interval, the time interval being equal to the amount of time which elapses when a specified number of pulses generated by the local oscillator is counted. The reference frequency of the phase-locked loop is derived from the frequency of the local oscillator.

Growing community of inventors

Turku, Finland

Matti Ylivakeri