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Appendix C
isofield diagram
(Also referred to as a charge-up diagram), this is a diagram showing the
distance at which the transponder will be charged-up to a specified voltage
(specified on the diagram). Moving inside these boundaries results in a higher
charge-up level in the transponder. The charge-up diagram depends on: the
transponder antenna, the voltage on the readout antenna, and the charge-up
time.
magnetic induction
The magnetic field strength formed around a wire when a current passes
through it.
major lobe
The field strength developed by an antenna forms a major lobe and two or
more minor (smaller) lobes.
noise sensitivity
How much a system is affected by noise is defined as noise sensitivity.
orientation
The angle of the transponder with respect to the antenna:
0
°
For Gate antenna = transponder at an angle of 90
°
to the antenna
For Ferrite rod = transponder in line with the antenna
90
°
For Gate antenna = transponder parallel to the antenna
For Ferrite rod = transponder at an angle of 90
°
to the antenna
readout antenna
The antenna used to charge-up and then readout the transponder.
readout diagram
A graphical indication of the antenna and transponder showing the "envelope"
or area within which the transponder can be charged up and the resulting
signal read.
readout range
The distance between the antenna and transponder at which the transponder
can be charged up and the resulting signal read.
readout speed
Some utilizations of the system require that a moving transponder be read. The
speed at which the transponder can be moving and still be read is the readout
speed
receive time (RX)
The time that the system is not transmitting (during this time the transponder
sends its ID to the antenna).
RMS
Root Mean Square, a method of measuring AC voltage whereby the indicated
voltage provides an average roughly the same as a DC voltage of the same
level.
selectivity (high)
A system with high selectivity can more accurately "select" a transponder, in
practice this means that transponders can be fairly close to each other and yet
still be successfully read.
selectivity (low)
If a system has low selectivity it means that there has to be more distance
between transponders in order to read them successfully.
separation between
Separation refers to how close together transponders can be and still be read.
transponders
side lobes
The two or more minor (smaller) lobes of field strength developed by an
antenna.
standard antennas
This manual describes the five antennas currently being produced by TIRIS.
Other antennas can be used, but they must satisfy certain restraints.
stick antennas
TIRIS currently utilizes two types of antenna: gate antennas and stick (or ferrite
rod) antennas. Stick antennas are cylindrical in form and consist of ferrite rods
with litze wire coiled around them.
transponder charge-up
The time that it takes for the capacitor in the transponder to charge up to 5 V to
enable it to transmit its ID signal back to the antenna.
36
Glossary of Terms
SCBU025 – November 1996
Summary of Contents for TIRIS SCBU025
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