| 摘要 |
In Doppler radar devices for measurement of distance or speed, it must be possible to synchronise the oscillator over a very wide frequency range. To form the deviation between the oscillator frequency fO and the synchronisation or Doppler frequency fD, a digital filter (9) with periodic weighting function h(t) is connected in series before the oscillator (24), its data input (D) is connected to the synchronising frequency (fD), and its clock input (T) is connected to the oscillator output (25). The data input (D) and the output (14) of the digital filter are connected to the inputs (D, A) of a multiplier (10), which is connected between the digital filter (9) and the oscillator (24). The circuit arrangement makes it possible to synchronise the oscillator over the whole range of the Doppler frequency, from zero (stopped) to the Doppler frequency which corresponds to the highest speed. <IMAGE>
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