Biomedical Engineering Reference
In-Depth Information
Fig. 12 Experimental setup for the characterization of the ultra-wideband (UWB) pulse radar
sensor, including packaged System-on-a-Chip (SoC) pulse radar and on-board antennas. The target
is made of a 0.5 cm thick board covered by an aluminum foil. The radar sensor is placed at a distance
( D ) from the target which may move for a displacement ( d ). A detail of the packaged radar testchip
mounting on test-board is reported in the insert on top right corner
In the second experimental test, the DG has been driven in order to produce only
two delays, one corresponding to a perfect time alignment between the two inputs
of the multiplier, and one corresponding to a total time misalignment between the
two signals. The delay is changed every 0.5 s. The measured output of the radar in
this case is shown in Fig. 11 b. In both the experiments, f RP was equal to 40 MHz.
Overall, the results of the functional tests demonstrate that the testchip works prop-
erly. Note that the DC offset (
50 mV), which can be eliminated during the digital
processing, is not an issue for this application aimed at detecting the movement rate.
Field Operational Tests
The complete radar sensor consisting of the SoC UWB radar and two identical UWB
antennas (one connected to the transmitter output and the other to the receiver input)
has been designed and realized on FR4 substrate ( ε R =
4.4, dielectric thickness of
1.6 mm and copper thickness of 0.35
m).The complete radar sensor has been tested
in operational field tests. The complete radar sensor board and the measurement
setup for the first operative tests are shown in Fig. 12 .
In a first set of operational tests, the target is made by plasterboard covered by
aluminum foil and is placed in front of the radar at a distance D . The target may move
along the axis radar-target for a displacement d around its quiescent position at a
distance D , with a given period (about 0.8 s). The results have shown that the radar
sensor is able to detect the three different targets of 26
μ
26 cm 2 ,13
26 cm 2 , and
×
×
13 cm 2 , for displacement movements d
13
×
=
2 cm around the quiescent position
at a distance D up to 70 cm.
The output voltage for the target of area 26
26 cm 2
70 cm)
is shown in Fig. 13 . The output voltage swing is about 10 mV. These results
demonstrated the radar capability of detecting small variation of the target position.
×
( d
=
2 cm, D
=
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