next topic »

[Reply #15 on:]

Why wouldn't you use a tag that would be clipped on their clothes at around the same level as the table edge, and then put a reader at every spot?  You would only need a 10-20cm read distance, which is doable, and you would meet the separation criteria so that you don't run into the issue of multiple tags in the same field.

The 125kHz tags and readers seem to have this range and it appears that you can even tune it up or down a little by using differnt sized antenas.

From what I have read, I agree with the idea that it will be difficult/expensive to read multiple tags with one reader.

[Reply #16 on:]

and it appears that you can even tune it up or down a little by using differnt sized antenas.

No you can't.
A reader will read any tag in the range of 105KHz to 150KHz and this is not affected in any way by the size of the antenna. I know I have designed readers.

[Reply #17 on:]

Why wouldn't you use a tag that would be clipped on their clothes at around the same level as the table edge, and then put a reader at every spot?  You would only need a 10-20cm read distance, which is doable, and you would meet the separation criteria so that you don't run into the issue of multiple tags in the same field.

The 125kHz tags and readers seem to have this range and it appears that you can even tune it up or down a little by using differnt sized antenas.

From what I have read, I agree with the idea that it will be difficult/expensive to read multiple tags with one reader.

That is maybe a good way. I road that it is possible to use only one reader with multiple antenas. So I need one reader and 4 or 8 antenas with a multiplexer.

Do you know a rfid reader which works good with arduino?

I think 10-15cm is fine.

And with one reader i do not disrupt the other readers .

[Reply #18 on:]

Do you know a rfid reader which works good with arduino?

As the arduino only received data it can work with any RFID reader. The hardest to cope with will be those with a USB output so avoid them.

[Reply #19 on:]

If you want reading distance, you'll have to forget about regular 125kHz cards or 13.56MHz RFID Tags. You'll need UHF or special long range tags.
UHF readers are also capable of reading multiple tags at one time, but you just want to read once in every location.
You can use just one reader, an antenna multiplexer (like this http://www.impinj.com/Speedway_Reader_Antenna_Hub.aspx) and as many antennas as spots. But we are talking about +2000 dollars. I don't think an Arduino will be able to handle the communication with the reader either, you might need a PC.

[Reply #20 on:]

Small-scale position tracking of individual persons/objects has been one of the big challenges of research across many universities and companies in the last few years --  I'm fascinated by it too but people still haven't arrived at a very consistent/universal/feasible solution.

In your particular case, you could try using a couple of IR cameras (especially if you pull out the Wiimote's camera, since it's well-documented) -- Place an infrared LED on each individual and you'll be able to track them in 3-dimensions. Still has the problem of requiring line-of-sight but at least it will be precise and inexpensive this way.