Getting lots of ST25RU3993_ERR_PREAMBLE and ST25RU3993_ERR_RXCOUNT errors during round

[JSchu.337]

Hello,

I´m testing the ST25RU3993 Eval Board with it´s firmware and I receive lots of ST25RU3993_ERR_PREAMBLE and ST25RU3993_ERR_RXCOUNT errors during inventory round.

My setup contains 72 Tags, all visible for the antenna. (another Reader detects about 70 per Round) If I set a non adaptive Q to 1024 slots I thougt to get about 952 empty slots, maybe some collisions and something about 72 Tags. But instead I find something between 10-62 Tags, something about 450 Empty Slots and 500 Collisions, caused by the two errors I said above. (more by preamble, less by rxcount and a few caused by others (the else in your commented debug print in gen2.c gen2SearchForTags())

I already checked the RXWAITTIME register (0x08) and the RXNORESPONSE Register (0x07), they are on default value.

A problem resulting of that errors is the adaptive Q. Because of the ST25RU3993_ERR_PREAMBLE errors the q increases a lot during round, but it should decrease because of the Empty slots...

Can you tell me what can be my problem?

Thank you very much,

Julien

[Nick K · Accepted solution]

​Hello JSchu.337,

Preample Errors and Collisions are often an indication for "bad" or noisy environemt. Have you "tuned" the antenna before scanning ? Do you use auto-retuning, and does this improve the situation over time ? What is your RX sensitivity ? Sometimes its better to degrease the sensitvity and make in not adaptive.

The problem with the fast increasing Q comes from the reader - TAG communcation problem. The more collisions the faster the Q increase. Collisions are weighted stronger then empty slots.

It is really hard to give a good answer without knowing your detailed setup you could send me a PM and we could discuss your project setup in more detail.

eg. Which antenna, which link settings, what is your measured reflected  power, which frequencies, what TAGs, possible noise sources, ...

BR

Nick