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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 procedure, 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 time shift of the echo signal, conclusions can be drawn about the size and movement of the obstacle. The same applies to whether the object is moving toward or away from the transmitter. From the change in the frequency spectrum, the nature of the reflecting body can be inferred. 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 at an extremely low power, less than 100 mW, which is much lower than that of cell phones and smart phones. 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).

Englisch: continuous wave radar - CW
Updated at: 11.02.2019
#Words: 242
Links: contention window (802.11) (CW), continuous wave (CW), carrier, signal, echo
Translations: DE

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