17
sim
re
de
A
sy
of
ag
RF
su
sp
El
25
Fi
m
th
fro
ne
6.
RF
78 Software N
multaneously
eading of diff
etermine the
SK and PR-A
ystem means
f the objects
gain the nex
FID is able
uch a way th
peed may be
The identi
lectronic Pro
56 bits in len
igure 6.21. F
much more co
he lengths of
om 36 to 14
ever has to re
Figu
Figure
.20. Securit
Security is
FID device
Networks
y trigger a la
fferent tags w
frequency,
ASK) and th
s that, whene
that have be
xt time. Afte
to successfu
hat each RFI
up to 640 Kb
ity of the
oduct Code. G
ngth. An ex
Figure 6.22 sh
omplex, beca
the subseque
40 bits, whic
eturn to 0.
re 6.21. Struc
e 6.22. The str
ty of RFID
a thorny iss
can be easil
arge number
would lead to
the coding u
he data rate o
ever tags are
een able to t
er a certain
ully transmit
ID then take
bps.
object is d
Gen1 uses 96
xample of th
hows the ID
ause it uses i
ent fields. N
ch means tha
cture of GEN1
ructure of GEN
sue in the w
ly read by a
of RFIDs, b
o collisions.
used (betwee
of the channe
e read simult
transmit are
number of c
t. The algor
s turns to tra
determined
6 bits, whilst
is ID for Ge
D fields in Ge
intermediary
ote that the s
at, for a give
Electronic Pro
N2 Electronic P
orld of RFID
a third-party
but the simul
Signaling is
en DSB-ASK
el. The anti-c
taneously, on
allowed to t
collisions, o
rithm is desi
ansmit. The
by the EP
t in Gen2 the
en1 is illustr
en2. This sol
y filters to de
serial numbe
en article, th
roduct Code
Product Code
D. Indeed, a
reader. In a
ltaneous
used to
K, SSBcollision
nly half
transmit
nly one
igned in
reading
Cglobal
e code is
rated in
lution is
etermine
er grows
he value
passive
addition,
www.it-ebooks.info
Précédent

- 202/262

Suivant