Identification Systems
English, Revision 03, Date: 12.07.2011
6
1.4.2
Transmission Range and Function
The field intensity of the magnetic alternating field decreases with an increasing dis-
tance between transponders and reading antenna. Thus the information exchange is
only feasible within a certain area.
The field length L and the field width B of the transmission range (see Figure 2 on page
6) will be defined via the parallel centre line through the reading antenna (road). The
distance between reading antenna and the sectional plane is indicated as S.
A faultless function of the system is guaranteed if the transponders and the reading
antenna move towards each other with the distance specified by S and within the
range defined by L and B - provided that they are properly aligned. The transponder
(line C, max. offset) will even be detected in case of an offset (deviation from centre).
Then the positioning impulse will be output with an offset. D shows the data-free area
in which no telegrams are output. This area has a width of 25 to 30 mm at nominal
reading height.
Figure 2
Length and width of the interception area (view from above)
Positioning is carried out according to the field compensation method. In the center of
the reading antenna the resulting field for the transponder will be erased. At the inter-
section to this region (registration gap or data-free range) the position of the transpon-
der at the object will be detected accurately and indicated (see table 3 on page 7).
Direction of travel
L
Magnetic
field lines
Line C
(max. offset)
Offset (Z)
Line A
Transponder
Area II
Area I
(Registration
ranges of the
reading unit)
Activation of the positioning pulse (dependent on the direction of travel)
D
Reading
antenna
B
