Any1 can recommend any Bluetooth class 3 devices for capturing contact data within 1m range? Or RFID tag?

Question

I'm looking for devices that able to capture proximity contact within 1meter range and able to capture the contact duration. Is there any passive RFID or semi-active RFID tag able to do it? or do I need to use bluetooth to pair? But how do bluetooth devices unpair themselves when they away from active pairing range zone? To save power consumption, would ZigBee able to achieve the same as Bluetooth class 3? Bluetooth is known for voice transmission. Can anyone tell me how bluetooth transmits data? Do provide me the sources/links to get the devices.

Answer 1

I am having trouble figuring out what you want to do here - detect an RF signal when a bluetooth devices comes within 1 meter of your thing? Record all the data being transmitted from the new bluetooth?

Bluetooth frequency hops on a psudo random sequence to one of 80 frequencies, that is open source data so you can read when and how it hops on an clear channel.

A slave device hops slowly across the sequence, and the bluetooth master hops faster, when the master asks for an ID from nearby devices and the slave responds on the same frequency they sync up and start hoping fast together. Thereafter if the slave doesn't report its ID before the packet the master will drop it from the network.

If you want a transcript of the data from a bluetooth master entering the network you have to buy either a bluetooth chip ~$5 or a spectrum and vector analyzer.

If you just want to know that an RF device is nearby use an RC network that boosts the voltage and an op amp after that for gain, cost you practically nothing and does the job just fine.

Hope this helps.

Answer 2

So I assume you have a (existing) contact of some sort, and 1 meter away you want some electronics that detects whether that contact is closed, and for how long....

Forget RFID, it is passive. You can detect proximity and identity, but the RFID tag doesn't really transmit a signal (it tells the receiver what to make of it).

Bluetooth can work, and the original idea of Bluetooth was actually having various appliances and electronic devices "talk" to each other (digitally). That failed (so far) on agreeing to a standard protocol, as usual (NIH syndrome).

I would use a cheap and cheerful FM transmitter and receiver which you can get for just a few bucks from Http://www.e-madeinchn.com. That's what I have done to detect whether my mailbox door (invisible from the house) is open or closed.

A Bluetooth solution would definitely have been more expensive.

ADDENDUM:

I think the word "contact" caused the confusion, what you want to detect is "proximity".

Yes, RFID can certainly do that, but every person must then have not only a unique RFID tag, but also a RFID Reader. And then every RFID Reader must be connected to some form of logic device which either stores (for later retrieval) who came within 1 meter with whom and for how long, or those data are being sent "real-time" to a "central processing logic", either by RF or Bluetooth (depends on how far the central station is away from the mingling crowd).

It is technically do-able, but I don't think it already exists, and it would be quite an interesting engineering feast.

I charge $25.-- per hour R&D time..... ;-)

Answer 3

Class 3 Bluetooth

Answer 4

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