Data Sheet

DATA SHEET
Technical changes reserved
0141 0316-70 07/2014
Operation
The radar module comprises of a highly integrated radar sensor with
sending and receiving part as well as a push-pull mixer. Careful circuit
layout and selection of suitable components guarantees the fact
that the module complies with the requirements of European ETSI
standard and possesses a generally valid CE permission.
Radar based motion alarm units work as per the Doppler principle:
the electromagnetic waves in the microwave range are reected
from the object and superimposed over a sending signal by a mixer
in the module. Therefore, the frequency of signal originating at the
mixer output is proportional to the speed: 44 Hz corresponding to a
movement speed of approx. 1 km/h. The amplitude of the signal is an
outcome of the size of the object and its distance to the sensor.
While PIR sensors react very insensitively to movements in straight
direction, the radar sensor shows its highest sensitivity here. On the
other hand, radar sensors are more insensitive to circular movements
around the sensor, while the PIR sensors clearly possesses the high-
est sensitivity here. Therefore, in modern safety related applications,
the PIR sensors and radar sensors are effectively combined.
The signal voltage at output of the mixer is still very low, in the maxi-
mum order of approx. 300 µV. Therefore, a subsequent amplier is
required with dened bandwidth (approx. 20 ... 900 Hz) which brings
the signal to a useful level, which can be then further evaluated over
a micro-controller. Application circuits for this are available on request,
alternatively modules with integrated ampliers are also available.
Handling recommendations
The sensor is susceptible to ESD danger due to wrong
handling. However, the regular precautions for CMOS
circuits are sufcient during handling of the component.
Touching the signal outputs should be avoided, before the module is
assembled on the circuit board.
The use of a multimeter for resistance measurement between the
connection pins can lead to damage of the module.
The proximity of uorescent lamps can lead to incorrect triggering.
Hence, the module should not be installed in direct proximity of uo-
rescent lamps. This effect can be suppressed by introducing a 100 Hz
notch lter in the ensuing electronics.
Because of its type of construction, the module is sensitive to sound
impacts. Just mounting over the pins is not sufcient, the module
should also be mechanically further secured.
Connection
Pin Function
1 Operating voltage 2.85 ... 3.30 V
2 Signal output
3 Ground
Antenna diagramm
Radar based motion detector
module RSM3650
B+B Thermo-Technik GmbH | Heinrich-Hertz-Straße 4 | D-78166 Donaueschingen
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