User's Guide

FUJITSU COMPONENT LIMITED
9
(Tx radio frequency) > (Rx radio frequency)
Q lag behind I by 90 degrees
(Tx radio frequency) = (Rx radio frequency)
Neither Q nor I has signal (=DC
Both Q and I has 0Hz when movin
Fig. 6 Wave forms of “I” and ”Q”
As shown in Fig.6, by Doppler effect, when Rx frequency get higher than Tx frequency, Q-
signal leads to I-Signal by 90 degrees, when lower, Q-signal lags to I-signal by 90 degrees.
This correlation is same for different frequency.
In case the object not moving only, only DC signal (0Hz) is output.
6-2. Application – Approaching/receding judgement by IF1/2(I/Q) output
As mentioned above, it is possible to judge if the object is approaching or receding. Fig.7
shows the waveform observed as I-signal and Q-signal on Oscilloscope, when there is the
object with a movement back-and-forth in front of sensor module, ie hands move back-and-
forth.
Fig.7 Approaching/receding judgement
Q
I
+90°
-90°
Receding
Approaching
IF frequency gets lower. (=slower)
IF frequency gets higher (=faster)
Q
I
Q
amplitude
I