CR95HF Data Rate, Subcarrier and 10%/100% Modulation Parameters

[JMcIn]

I've been using the M24LR-Discovery kit to evaluate the read range to our 15693 tags. My measurements are in the 2.6 inch to 3.5 inch range, depending on how I set the Data Rate and subcarrier settings. The best range is achieved with 'LOW' date rate, and no subcarrier. The 10%/100% modulation setting has no effect on range as far as I see.

Are there reasons to NOT use LOW date rate and NO subcarrier for our reader?

How should I determine to use 10% or 100% modulation?

Thanks!

[Brian TIDAL]

Hi,

according to ISO 15693-2

• for modulation (§7.1): tags shall decode both
• for subcarrier (§8.2): tags shall support both mode
• for datarate (§8.3): tags shall support low and high data rate

The NFC Forum [DIGITAL] 2.0, limits the choice of the modulation (100%), the bit coding, the data rate (high) and the subcarrier (single). Anyway, an ISO 15693 tag supports low data rate.

The CR95HF supports both 10% or 100% modulation. I would personally prefer 10% modulation (more energy delivered to the tag compared to 100%)

Rgds

BT

[JMcIn]

Brian,

Yes - agreed, the 15693 tags must support 10 and 100%, single and dual subcarrier, and low/high data rates. It's my understanding that in all these cases, it is the reader that determines which mode to use. Your reasoning on using 10% over 100% makes sense to me regarding the modulation depth. Do you have any thoughts on single vs. dual subcarrier? As I noted, we see better range with single, so I'm thinking of using single subcarrier - but I don't want to overlook some hidden advantage of dual subcarrier.

Thanks again,

Jim

[JL. Lebon]

​Hello Jim,

You can safely use the single subcarrier mode. There is no real advantage of dual subcarrier over single. It is just a matter of how the reader implement the decoder.

The single subcarrier mode may sometime gives better read range than dual, as you noticed. It is due to the fact that modulating in single use less power for the tag than modulating in dual (the tag modulates half of the time compared to dual). So, if you are at the limit of the read range, it can help. But read range is dependent on many other factors.

Best regards.

[JMcIn]

Great - thanks for your help JL.

Jim