Bosch CR5CBCC User Manual page 4

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Topic CR5CBCC User Manual
frequency shift. This allows range and velocity to be found with one radar set. Triangle wave
modulation can be used to achieve the same goal.
As shown in the figure the received waveform (green) is simply a delayed replica of the
transmitted waveform (red). The transmitted frequency is used to down-convert the receive
signal to baseband, and the amount of frequency shift between the transmit signal and the
reflected signal increases with time delay (distance). The time delay is thus a measure of the
range; a small frequency spread is produced by nearby reflections, a larger frequency spread
corresponds with more time delay and a longer range.
Figure 2: CWFM radar chip
Ranging with an FM-CW radar system: if the error caused by a possible Doppler frequency can
be ignored and the transmitter's power is linearly frequency modulated, then the time delay is
proportional to the difference of the transmitted and the received signal at any time
References for chapter 2 of this document:
https://en.wikipedia.org/wiki/Continuous-wave_radar
This work is released under CC-BY-SA: http://creativecommons.org/licenses/by-sa/3.0/
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CR5CBCC_User_manual.docx
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