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Comment by IndrekR | Hacker News Reader

Used to develop readers based on similar UHF chips (868 MHz in EU). They were quite expensive compared to printed bar codes those were replacing. Also large. With (folded) antennas we are still talking about 40*10 mm minimum for the label. You can not use them on metal surfaces. Readers nearby will interfere as it works by EM wave backscattering, unlike NFC which is essentially a transformer (with electric field intentionally supressed usually). I think it still is a solution looking for problem. QR codes are cheap and NFC (14 MHz) readers are everywhere.

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I have a hobby project where I am using UHF tags for counting poultry. The advantage that it gives me is long range (few meters) compared to LF / HF tags. QR code also wouldn't work due to size and distance.

Here's a video.

https://youtu.be/_iGn_pZ3IkY

Really nifty; can I ask what tags you are using? (are they off-the-shelf)

Would be interested in doing something similar

These:

https://www.chafon.com/productinfo/1070742.html

Bought them on Alibaba.

This looks immensely useful

I've been thinking about ways to count my chickens, making sure they return to the coop and don't get locked out at night. Most of the time all tge birds get in, but occasionally some will dawdle and wind up sitting outside a locked coop door.

You mention this can read for a couple meters. Can it read all the members of a flock, so I could mount a single transmitter in the ceiling if the coop, or is it one at a time, so something that should live above the door

I haven’t played with any stationary antennas but I think it’s possible.

The scanner that is used in the video has configuration for transmit power. At its maximum setting, the range is 15 feet with clear line of sight.

Tags with larger antennas, generally speaking, have longer range but might be too big for younger chickens.

So overall there are a lot of variables.

Looking at Chafon and some other vendors, they seem to have a decent amount that might work for what I want. Do you purchase your stuff from Aliexpress? Or is there another vendor worth using

I did work with that recently. Did a few cool demos.

The tags got cheaper and you can even get tags that are intentionally designed for metal surfaces. Unlike NFC (or barcodes, obviously), you can read hundreds of tags essentially simultaneously. But because the reading is far from being perfectly reliable (one thing we found out is that human body blocks the 868MHz RFID completely, even at something like 50dBm EIRP, which is well above what is considered safe for human presence) the applications are indeed somewhat limited.

But apparently there are two classes of applications where this technology is really common: libraries and bulk checkout at sports equipment retailers (seems oddly specific). Both of these things also benefit from the "advanced" features of UHF RFID tags like dual-mode RFID/EAS tags and ability to permanently deactivate the tag by simple command.

When you say "bulk checkout at sports equipment retailers", I guess that you might be referring to Decathlon, that has been adding unique UHF tags to every product for years, both for stock control and checkout.

Anecdote about it, 2019: https://mastodon.social/@russss/102674489508219187

shopping at uniqlo is really nice where you can just dump everything you want into the scanner

https://www.huayuansh.com/uniqlo-global-stores-applied-rfid-...

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