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I hope someone can help me with a doubt about the way RFID works, regarding communication with RFID tags.

I am working with a Motorola FX7400 reader, I know it works in a frequency range (902-928 Mhz). I want to know if is possible to set it to work in a specific frequency while communicating with RFID tags (for example, that it works in the frequency of 926 Mhz always with all tags).

Is the nature of RFID communicate with a tag in a frequency, and with another tag in another different frequency? Or is possible to do what I explained?

The reason is that I don't want RFID signals cause noises with others devices (used to test frequencies by the way).

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  • \$\begingroup\$ A properly designed RFID excitation coil/antenna won't emit energy very far (as opposed to an antenna that is intended to transmit proper EM waves to be received at some distance). \$\endgroup\$ – Andy aka Nov 26 '14 at 22:35
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Yeah, technically you can, but you have to change hardware.

The frequency range is there to meet tolerances in both the sending and receiving coils. The higher the Q of the coil, the smaller the frequency range it will respond to (sending or receiving). If you want your coil to work at an exact frequency, you need, essentially, infinite Q.

So while you can not get an exact frequency in reality, if you can design a higher-Q replacement coil for the reader you can narrow its frequency range.

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I general there is absolutely no problem, to set an UHF reader to one specific frequency, from an technical standpoint. However, the FCC, and may other regulatory bodies require you to use FHSS (see: Regulatory status in the EPC Gen 2 band). So, you simply may not be allowed to operate your reader at one frequency.

As a consequence, it might be that Motorola won't let you turn off FHSS in your reader, but again, that is not a technical restriction.

Oh, and finally: FHSS is used in non-licensed parts of the spectrum exactly to avoid or limit the interference between non-coordinated, neighboring devices, for all I understand.

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