How do I enable Strong modulation on NTAG216

Hi all, I’ve had my implant for years, and was messing with it again today to fix an old spelling mistake on a record it contains, and I noticed the modulation setting in the basic information that’s first displayed when it’s read in.
I see in all sorts of places peoples logs of their tags configuration settings, seemingly most of them say something like ‘Strong modulation - enabled’ somewhere, but mine doesn’t, and I’m wondering if that’s why the thing is so infernally difficult to read; it being very shallowly implanted, but it needing to be virtually rammed right up to my phone and stuff to do anything with.
My CFG 0 at address E3 is 04:00:00:FF, which unless I misunderstand (which I probably have done), should set bit 2 of the FDP and MIRROR configuration byte to the required value of 1 to enable strong modulation, and other peoples configurations seem to bear this out, so why on earth is mine reporting itself as 'Strong Modulation - disabled and how do I remedy this?

What is your phone and have you 100% found the sweet spot? Do you have a 13.56Mhz xLED

Hello, my phone is an HTC One M8, and like my HTC One M7 before it, its NFC antenna is around the camera lens, so yeah, I’m sure I’m getting the sweetspot correctly. I also have extremely short range read issues when using various NFC modules on Wemos D1 mini and Arduino projects, hence my interest in trying to enable the strong modulation mode that most other folks seem to have, on my implant. If nothing else to see if the read range can be improved even slightly, because the thing is almost useless at the moment.
I don’t have the field strength tester I’m afraid.

Can you post a screenshot of what the NXP TagInfo app says when you successfully scan your tag (rammed right up to your phone). Here’s my xNT being scanned and you’re right, it says “Strong load modulation enabled”:

It will give us more info about your tag and possible insights into why your load modulation would be set to “normal” (not the default).

Here is a diagram I found of the NFC antenna on your phone:

The M8 has an antenna that is very poorly shaped for coupling with the helical antennas in the x-series tags. It’s also traveling through a metal casing.

Since you seem pretty familiar with sending commands to the tags, you could try using the information in page 19 of this document [PDF] to set the Strong load modulation to enabled. If your implant is an xNT, I recommend you purchase a few NTAG216 stickers online and practice with them. You may also want a better NFC reader to interact with the tags during testing.

What do you consider “extremely short range”?

It is not uncommon to nearly have to touch the phone to get a read, depending on the phone. I can get about a 7mm with the dangerous things PN532 module. With my Red Hydrogen One phone I can get 1cm or more (best NFC range on a phone I’ve personally witnessed), but my S7 it’s only about 2mm even with the ideal orientation and position (using an xLED to find this the ideal position and orientation is super important to get consistent reads)

This is the NTAG216 datasheet
Page 18 shows the config bytes for strong modulation.
You need to write an 04 into the first byte of E3

I was able to do disable and renable on an NTAG216 card using NFC Tools (pro)
This is assuming your auth byte(E3, byte 4) is FF (unlocked)…

Warning: I’m pretty sure you can essentially brick your tag if you write the wrong thing to the E3 page so to this at your own peril.

In NFC Tools, go to Other, then Advanced NFC Commands

Send the command A2E3040000FF
You should get a 0A result.

Rescan and it should be enabled.

BTW, testing with the card, it made no difference in read range with it enabled or disabled.

Hi guys… yeah “strong modulation” has nothing to do with “signal strength” … As you should know already, a passive tag works by inducting power from the mag field generated by the reader… and, to communicate with that reader it modulates the field. How does it do this? It does this by basically toggling a resistive load on the inductor coil (antenna) so that it pulls more or less power from the field. The reader can sense this and determines 1s and 0s as the power drain modulates.

Some readers require a larger threshold between median (resistance off) and dampened (resistance on)… or they have terrible receiver circuits and any noise in the environment creates problems detecting these small changes in the field… so stronger swings in power modulation is required… this is what “strong modulation” does… it increases the resistive load to swing the power draw harder when engaged… this makes it easier for readers to detect the changes… so if anything, it’s more of an error correction mechanism to overcome noise than a performance.

Nearly all performance problems have to do with the shape of the reader antenna not producing a strong magnetic coupling with the tag / implant. I hope this video helps make sense of things in this regard.

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