Interrogation Zone Basics

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These questions are derived from the Self Test Software Practice Test for CompTIA’s RFID+ exam.

Objective: Interrogation Zone Basics
SubObjective: Given a scenario, solve dense interrogator environment issues

Multiple Answer, Multiple Choice

You are instructed to implement an RFID-based tracking system on all the dock doors in a manufacturing facility.

Which two options should you implement to minimize interference between overlapping interrogation zones? (Choose two.)

  1. Optimize the power levels of the interrogators.
  2. Use interrogators in dense-reader mode.
  3. Use an anti-collision protocol.
  4. Implement shielding between the dock doors.

Answer:

A. Optimize the power levels of the interrogators.

D. Implement shielding between the dock doors.

Tutorial:

You should optimize the power levels of the interrogators and provide a shielding between dock doors to minimize the interference between overlapping interrogation zones. You must optimize the power levels to generate enough power and backscatter a signal to the interrogator’s receiving antenna to prevent interference between overlapping interrogation zones. You can also provide shielding between the dock doors to prevent radio frequency (RF) waves from passing through and minimizing the interference between overlapping interrogation zones.

While using more than one interrogator in close proximity, dense-reader mode allows interrogators to hop between channels within a certain frequency spectrum to prevent interrogators from interfering with each other. In dense-reader mode, interrogators work at a frequency range of 902 – 928 MHz that limits the read range of interrogators. This will result in lower read rates. Therefore, we should not use interrogators in dense-reader mode to minimize interference between overlapping interrogation zones.

An anti-collision protocol is used by RFID interrogators to prevent collisions when reading more than one tag in the same interrogator’s field. An anti-collision protocol prevents collision within a single interrogation zone. While preventing collision, an anti-collision protocol enables an interrogator to identify tags one by one. This protocol cannot minimize interference between overlapping interrogation zones.

Reference:

RFID Journal, Why UHF RFID Systems Won’t Scale, http://www.rfidjournal.com/article/articleview/1056/1/82/

RFID Journal, UHF RFID’s Key Constraints, http://www.rfidjournal.com/article/articleview/2244/1/128/

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