For example -there is a 30*30 meter warehouse with a lot of metallic
products- to ensure fast and reliable reading does one go for a dense
reader deployment with reader controllers, or metalic rfid tags in
normal reader configuration could do the job. How about a wi-fi system
or a case when you have temp sensor in tag?
Hi Poster,
Your description is somewhat general. Generally spoken, you should
take into account things like: orientation of objects, type of label,
RF environment close to and far from the tagged objects, available
hardware (and frequency bands), etc.
The most difficult thing (in the UHF applications that I saw) is to
guarantee detection in a certain zone (for example 99.8%), but to
guarantee no detection in other zones. This is because of multi path
propagation. In a multi path environment the coverage of the RFID
system is like the "plot" of a (full) paint can falling from the
stairs. For some applications you can get better results with
multiplexers (so you have, for example, 4 antenna outputs).
Implementing an RFID application is a (long) discussion / trade-off
between functional requirements and technical possibilities/
limitations. In many cases you need to change constructions, add
things, to create the correct environment for a good functioning
system. It may also affect working procedures.
When you talk about a multi reader environment, you may also
experience reader to reader interference. Sometimes a multiplexing
scheme may help (in combination with frequency planning), but this
reduces number of reads/sec.
When you are participating in a project, be very careful when
guaranteeing figures. You need at least to understand RF propagation,
RF measurement and the protocol that is used.
As you mentioned "metallic products" you need labels specially
prepared to give some reasonable performance when mounted on metallic
objects. When metallic objects are close and adjacent to each other
(label in between) performance will drop significantly. I assumed that
you are talking about UHF 800-900 MHz systems.
Best regards,
Wim
PA3DJS
www.tetech.nl
the address is OK when you don't forget to remove abc.
