RFA1 RADAR ACTIVATOR

Datasheet

Principle of Operation

RFA1 is a movement sensor containig a Doppler Radar module K-LC1a. Signal acquisition, amplifier

and digitizer are built in hardware, while timing and output are processed in a microcontroller.

RFA1 can operate in two modes:

•

Continuous mode, where the Radar module is always powered.

•

In pulsed mode, the Radar module is powered during approx. 4us and switched off during

200us (i.e. duty cycle of around 2%). During the off time, signal is stored in a sample&hold

(S&H) circuit.

Signal output frequency of the Radar module is 44Hz/km/h or 158Hz/m/s. Radar output voltage

depends on reflectivity, distance and direction of the moving object. It ranges from a few µV to some

mV.

This input signal is filtered and passes a band-stop at 100Hz. This reduces the influence of fluorescent

lights in countries with a mains frequency if 50Hz.

After a gain-adjustable amplifier, the amplified signal passes a window comparator. Comparator signal

contains double frequency of the input signal and is read by a microcontroller. Microcontroller performs

some digital filtering, timing and output control.

Fig. 4: Block Diagram

Application Notes

Connection Diagrams

Open collector output is universal and allows many different configurations. Fig. 5 shows two typical

situations. Output and RFA1 operating voltage may also be connected to separate power supplies.

Maximum output current should not exceed 20mA.

Maximum supply current is 45mA (continuous mode) or 10mA (energy saving mode).

© RFbeam Microwave GmbH www.rfbeam.ch

Page 4/7

DC

DC

S&H

1Hz ..4kHz

A = 1000...10'000

100Hz

T = 1s ...30min

4us/200us

6V...24VDC

NPN Output

Ground

Fig. 5: Examples: Left Relais, Right Controller

6 ...

24VDC

+

1

3

2

Ground

Output

Supply

6 ...

24VDC

+

1

3

2

Ground

Output

Supply

Controller

10k