Can you make it compatible with ChampionChip (now merged with MyLaps)? Many runners have their own chips, and that would be a good standard to work from. You can pick up
In response to the comments and answers about the applicability of this technology to racing, I can say that I've run at least two dozen races with RFID tags, and have never had a problem with tag collisions, misses, or accuracy/finish order.
For redundancy, use two mats, and program in the rate at which runners are crossing. Then, if the first mat has a problem, you can use the second and extrapolate the time to cross the line.
Find a race that uses disposable chips, or just keep a pair from your next race, and see what you can come up with. Alternatively, this site sells personalized tags.
It's actually fairly cheat if you know how to do it, this isn't something I'd recommend for someone new to electronics though. You could probably build a decent reader for under $5. Why not look at prebuilt readers and tags like the following:
Seeedstudio Reader
Seeedstudio Tags
ADDED
The following mainly covers DIY tags.
If still interested after reading this ask questions and we can talk about DIR readers.
The price of RFID tags is usually low enough that it is economic to buy them complete BUT you can "roll your own" and there may be advantages in doing so.
For a very raw DIY approach the Microchip MCRF355 IC datasheet here allows you to bild receiver coil etc. BUT these ICs are not readily obtained and the datasheet is dates 2002, so I'd consider them a learning exercise.
A 13.56 MHz RFID design guide from Microchip found here and dated 2004 shows how the above IC can be employed and gives valuable insight into general principles.
[Antenna Circuit Design for RFID Applications - Mrcrochip AN710](Antenna Circuit Design for RFID Applications) provides extensive antenna design and performance information. Highly valuable.
As an indication of how small RFID tags can 'bee'.
Related to a paper by Dr. Whitehorn and colleagues which I have not yet located.
A moss carder bumblebee, Bombus muscorum.
NXP Forum Mifare RFID / NFC system - more complex than you want but useful.
Demo board related to above $88
TI "Tag It" transpoonder inlays $US0.35/5000.
This the sort of thing that you compete against when considering making your own tags. See below.
Texas Instruments Tag-it™ HF-I standard transponder inlays consist of 13.56-MHz high-frequency (HF)
transponders that are compliant with the ISO/IEC 15693 and ISO/IEC 18000-3 global open standards.
These
products offer a user-accessible memory of 256 bits, organized in eight blocks,
and an optimized command set,
available in five different antenna shapes, with frequency offset for integration into paper, PVC, or other
substrates.
The Tag-it HF-I standard transponder inlays are manufactured with TI’s patented laser tuning process to provide
consistent read performance. Prior to delivery, the transponders undergo complete functional and parametric
testing, in order to provide the high quality that customers have come to expect from TI.
The Tag-it HF-I standard transponder inlays are well suited for a variety of applications including, but not limited
to, product authentication, library, supply-chain management, asset management, and ticketing/stored value
applications.
Tag insert Related
Tag insert - Related
Added:
Here is an immensely informative application note from a company with a number of potentially relevant products.
ib technology quad reader tag is usful for its nicely minimal circuit diagram plus wealth of application information.
But wait, there's more (from the same people).
home page
Range of reader modules
Reference design kits ..... one example
Evaluation kit
Datasheets and application notes looks very useful
Best Answer
By reading the standards documents for each one.
I know that in LF at least, the data rate is normally a simple divider from the carrier frequency. A 128 kHz carrier might be divided by a factor of 32 or 16 to create a data rate 4 or 8 kbps, for example.