Functionality and Technology of Radar Sensors
The radar sensor developed by Baumer allows you to measure the distance of objects over large distances. Besides measuring distance, it is also possible to measure the relative speed of the detected object.
The sensor is based on Frequency Modulated Continuous Wave (FMCW) technology. Here the carrier frequency is continuously modulated (bandwidth) within a small range. When the signal reflects off an object, the distance and speed of the object can be measured through frequency comparison.
The sensor uses a very high carrier frequency, which allows creating a very narrow beam cone. This allows detecting even small objects from great distances without being affected by neighboring objects.
Baumer radar sensors use the Frequency Modulated Continuous Wave (FMCW) method. In this method, the radar sensor emits a frequency (f) that changes continuously over time. In this way, a frequency sweep is created. The difference between the minimum and maximum frequency is called bandwidth (Bsweep).
The frequency sweep is repeated periodically with sweep time (Ts). One type of modulation is the sawtooth option shown in the figure. Alternatively, triangle wave modulation can be used. The time duration of this periodic modulation is called sweep time (Ts). During the sweep period the frequency is continuously increased, for example from 122 GHz to 123 GHz.
When the emitted radar wave hits an object within the radar cone, part of the signal is reflected. This can be detected as an echo signal on the radar sensor.
Due to frequency sweep, the echo signal has lower frequency than the emitted signal. The radar sensor detects the difference between the current frequency and the received frequency (frequency pulse fb) as the measured signal.
The distance R between the radar sensor and the object is determined by the detected frequency sweep (fb), sweep time (Ts) and bandwidth (Bsweep).
Shortcuts:
td = Execution shift
Ts = Scanning time
R = Range
c = Speed of light
fb = Frequency pulse
Bsweep = Bandwidth
