| 摘要 |
An arrangement in radar equipment for locking the frequency of a controllable local oscillator includes a sweep generator (10) which supplies a periodic linear control voltage to the local oscillator (3), a microwave generator (1) which generates a transmitter signal, the generator and the local oscillator each being connected via a multiplier (2, 4) to a mixer (5) in order to provide an intermediate frequency signal of the equipment, and a phase-locked loop (6, 7, 8, 9) for locking the local oscillator signal to the transmitter signal. The arrangement further includes a first selective circuit (11) including a low-pass filter in order to give an output signal if the frequency of the signal obtained from the mixer lies within a certain low frequency range compared with the intermediate frequency, a second selective circuit (12) including a band-pass filter in order to give an output signal if the frequency of the signal obtained from the mixer assumes a value in a range about the intermediate frequency, a first and a second detector (13, 14) for detecting respectively the said output signals, and logic circuitry (16) connected to the first detector and to the second detector and to the sweep generator to provide a stop signal for the sweep generator during a time interval which corresponds to a period of the linear control voltage only if an output signal is obtained from the second detector after an output signal from the first detector is obtained. <IMAGE> |
