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continuous wave radar (CW)

CW radar stands for Continuous Wave Radar. It is a continuous wave radar in which the unmodulated carrier signal is transmitted continuously and the echo signals are received continuously. CW radars are based on the Doppler effect. The transmitted RF signals are reflected by moving bodies and are received and evaluated again as echo signals by the transmitting device.

According to the method, in this radar RF signals with a narrow directivity are emitted from the transmitting antenna and reflected by moving people, animals or objects. The reflected echo signals are received by the transmitting/receiving device and their amplitude, phase shift and frequency spectrum are compared with the transmitted RF signal and evaluated. From the magnitude and the temporal shift of the echo signal, conclusions can be drawn about the size and the movement of the obstacle. The same applies to whether the object is moving towards or away from the transmitter. From the change in the frequency spectrum, conclusions can be drawn about the nature of the reflecting body. Distance determinations are only possible with pulse operation or with two different carrier frequencies. For example by means of frequency shift keying.

CW radars transmit with an extremely low transmission power of less than 100 mW, which is considerably lower than that of mobile phones and smartphones. CW radars are used as short-range radars in automotive technology. In addition to the simple, unmodulated continuous wave radar, there is also the frequency modulated continuous wave radar, Frequency Modulated Continuous Wave (FMCW).

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Englisch: continuous wave radar - CW
Updated at: 11.02.2019
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Translations: DE