| 摘要 |
PCT No. PCT/SE92/00004 Sec. 371 Date Jul. 9, 1993 Sec. 102(e) Date Jul. 9, 1993 PCT Filed Jan. 8, 1992 PCT Pub. No. WO90/06627 PCT Pub. Date Jun. 14, 1990.An arrangement in tuning resonance modules includes a cavity and resonance body, which is steered to resonance position by a motor, which is driven by a voltage as long as there is a phase difference between the input signal to the resonance module and the output signal (called the measuring signal) from the module. The input signal is of high frequency, and it is desired now to transpose the signals down to low frequency for preventing interference with the measuring signal. The arrangement therefore includes a high-frequency oscillator controlled by a voltage and having a frequency range within which lies the frequency of the incoming signal. From the oscillator output signal and the input signal there is formed in a mixing means the difference between the signals, and in a second mixing means there is formed the difference between the oscillator output signal and the measuring signal such as to form hereby two low-frequency signals. These are compared in a phase detector with respect to phase position. For a phase difference the detector gives a voltage, but for phase equality the detector gives zero voltage. |
