| 摘要 |
A radar-based distance measurement apparatus comprises a microwave circuit comprising a frequency generator which produces a microwave frequency signal, the frequency of which is modulated by an amount determined by a modulation signal applied to the frequency generator, a temperature sensor which measures the temperature of at least a part of the microwave circuit, compensating means for processing the output of the temperature sensor to produce a compensated temperature signal using information derived from the drive signal and an echo signal detected by a microwave detector; and a frequency regulating means which is adapted to receive the compensated temperature signal and to regulate the frequency of the signal generated by the frequency generator, thereby at least partially correcting for the effect of changes in temperature of the frequency generator. Because the compensating means modifies the output of the temperature sensor in a closed loop using information derived from an echo signal, the frequency regulating means can regulate the frequency output by the frequency generator-keeping it as close as possible to an ideal constant value-despite changes in its temperature.
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