Patent ID: 6973121

Claim:
A repeater system for receiving a modulated input signal and for transmitting a modulated output signal, comprising: a clock oscillator for providing a repeater system clock; a demodulator for demodulating an input signal to obtain a demodulated signal, the input signal being the modulated input signal or a signal derived from the modulated input signal, the demodulator including: a first mixer which is arranged for receiving the input signal at an input port, the first mixer additionally having a local oscillator port and an output port; a first controllable oscillator connected to the local oscillator port of the first mixer, the first controllable oscillator being arranged for providing an output signal which is derived from the repeater system clock; feedback means having a first input for receiving a frequency of the signal at the output port of the first mixer as an actual value and a second input for receiving a desired value for the frequency of the signal at the output port of the first mixer, the feedback means being arranged for determining a first control value, which is applied to the controllable first oscillator, the control value being determined such that the actual value approaches the desired value; a modulator for modulating the demodulated signal to obtain a modulated signal, the modulated signal being the modulated output signal or a signal from which the modulate output signal is derived, including: a second mixer which is arranged for receiving the demodulated signal at a input port and for providing the modulated output signal at an output port; a second controllable oscillator connected to the local oscillator port of the second mixer, the second controllable oscillator being arranged for providing an output signal which is derived from the repeater system clock, the second oscillator being controlled by a second control value; and a controller for receiving the first control value and for providing the second control value, the controller being arranged for determining the second control value on the basis of the first control value and a predetermined value of the frequency of the modulated output signal such that the frequency of the modulated output signal approaches the predetermined value.