Question on UCODE 8 behavior under auxiliary CW interference during reader communication

[Zhy889]

Dear NXP Technical Support Team,

I am currently conducting academic research on passive UHF RFID systems and would like to consult you regarding an observed behavior of the NXP UCODE 8 tag under a specific RF excitation condition.

In our experiments, during normal EPC Gen2 reader–tag communication, we introduce an additional continuous-wave (CW) signal at a different carrier frequency (no data information) from a USRP device. When the auxiliary CW has relatively high power, we observe that:

UCODE 8 tags fail to correctly decode reader commands and the communication breaks down.

In contrast, under the same experimental setup, Impinj Monza 4 tags can still maintain communication and, in some cases, show extended readable distance.

We understand that EPC Gen2 tags are designed for single-carrier operation and that auxiliary CW signals are outside standard operating assumptions. However, we are interested in understanding whether this difference may be related to implementation-level differences, such as:

a. RF front-end selectivity or matching bandwidth

b. Rectifier or envelope detector nonlinearity

c. Downlink demodulation architecture (e.g., envelope detection, filtering, timing recovery robustness)

d. On-chip filtering or interference suppression mechanisms

Our question is not about protocol compliance, but rather about whether UCODE 8 has known sensitivities to strong out-of-band CW signals, or if there are architectural characteristics that could explain the observed decoding failure compared to other Gen2 tags.

Any insight you could share at a high level (even without revealing proprietary details) would be greatly appreciated and very helpful for correctly interpreting our experimental results.

Thank you very much for your time and support.