C. Evaluation
The following results have been obtained from the performed
tests described earlier.
1) Performance Test: This test investigated the interplay of
the mobile phone with the RFID tag and the field detector. The
Nokia 6131 NFC, a clamshell phone, and the Nokia 6212 Classic,
a bar type phone, were used to touch the meter’s enclosure
at the position where the RFID tag/field detector was located.
They were aligned in four different directions (vertical or horizontal
with display up or down) to read the RFID tag. Ten
attempts per direction and mobile phone have been performed.
The results obtained from this test indicate that the Nokia 6131
NFC has a better reading performance. Independent from the
mobile phone’s direction, all attempts to read the RFID tag as
well as all attempts to trigger the field detector were successful.
This resulted in 100% of established Bluetooth connections.
Using the Nokia 6212 Classic showed different results depending
on the direction. Holding the mobile phone vertically
with display to front only four attempts resulted in successful
Bluetooth connections of four successful read-outs of the RFID
tag. A horizontal direction with display to front revealed similar
results of only three successful connections. Holding this mobile
phone with its display down onto the device also resulted
in 100% of successful connection independent whether it was
aligned horizontal or vertical.
2) Cross-Over Test: This test revealed that each attempt to
establish a connection either in part one ore part two of this test
was successful without the need of a manual interaction using
the devices keypad.
In case the field detector recognized any NFC enabled mobile
phone which did not attempt to establish a connection to the
sensor device, it automatically switched OFF Bluetooth after 20
s and went to idle mode again.
3) Feasibility Test: To evaluate the feasibility of the overall
system, 12 healthy volunteers (three female, mean age 34.
5 ± 8.3 years) performed the same data acquisition procedure
at least five times on a single day. They used the Nokia 6212