Data Sheet
© RFbeam Microwave GmbH
|
Schuppisstrasse 7
|
CH-9016 St. Gallen
|
www.rfbeam.ch
|
K-LD7
|
data sheet 12/2020 - Revision B
Page 6 / 23
Speed and
direction measurement
Every moving object in front of the sensor generates a
Doppler frequency at the analogue outputs of the RF
frontend. This Doppler frequency is proportional to the
speed of the object. Moving direction is defined by
the phase shift between the I/Q signals.
The K-LD7 calculates the speed and the direction
for all raw targets. The direction is represented by
the sign of the speed. A positive speed represents
a receding and a negative speed an approaching
movement.
The calculated speed is only correct if the movement
of the object is radial to the sensor. If the movement
is tangential the speed needs to be compensated by
the angle of the movement compared to the sensor.
Distance measurement
The distance measurement is based on the FSK
principle. The signal processing unit quickly changes
between two discrete RF frequencies and measures
the ADC values for both transmitting frequencies
which are available in the raw ADC data (RADC). After
the detection of all raw targets above the threshold,
the distance for each target is calculated based on
the phase difference in both ADC signals.
Angle measurement
The angle measurement is based on the angle of
arrival principle. After the detection of all raw targets
above the threshold, the angle for each target is cal-
culated based on the phase difference between the
two receiving channels.
The angle is calculated in degree and valid between
± 90 °. If an object has an angle of zero it is directly
in front of the sensor. A positive or negative angle
defines if the target is more on the right or left side of
the sensor.
Figure 5: Positive and negative angle definition
0°
+90°
-90°
D
C
B
6
5
4
3
2
1
A
2
1
4
3 5
B
A
C
Plotdate: 14.08.2019
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document only for the purpose it was delivered. © RFbeam Microwave
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Drawing Nr.
A4
1 / 1
Blatt / Anz.
Project
Scale
1:1
Material
Tolerance
Format
Prepared
Reviewed
Object
Surface
RFbeam Microwave
Schuppisstrasse 7
9016 St. Gallen
Switzerland
State
Index
XX
YY
XX
YY
α
moving object
radar sensor
Figure 6: Tangential speed compensation
v
real
=
cos()
v
measured
[km/
h]