How do transponders work ?

How do transponders work ?

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steve-V8s

Original Poster:

2,920 posts

259 months

Sunday 14th May 2017
quotequote all
Please can someone give me an idiots guide to transponders.

As I understand it a receiving system usually an inductive loop is located somewhere on the track, say the start finish line and the pit entrance, as a car passes the loop it responds with a unique code which can be associated with the particular car. Software can then count laps, lap times and time in the pits. If I have this roughly right how does the transponder send the data is it RF or via inductive loop ? Is there any standard for the data format.

b0rk

2,376 posts

157 months

Sunday 14th May 2017
quotequote all
The transponder will be either active (with a power source) or passive where the induction loop excites the chip. Motorsport transponders will generally be active, hard wired to the car and operating in the UHF band, probably using kit from MYLAPS.

The transponder/chip is ultimately a type of RFID device the vendor may have decided to follow the standards such that the transponder and reader are interchangable between manufacturers or may have developed a propitiatory data format tying the users into sourcing everything from one vendor.

The air interface is described in ISO/IEC 18000 part 6 (and sub parts 61 to 64).

Issues around cross vendor accuracy (and sponsorship) will see many series opt to single source the timing solution, the name on the kit may not necessarily be the manufacturer.

An active transponder will be constantly transmitting but only read when the transponder passes over the antenna loop(s), the overall system may now include a return link to transmit timing data back to the car for driver display. Any return link system will be outside of the RFID standards and likely propitiatory to the system vendor.

The complexity of the system will be in how the reader achieves sub second timing accuracy from what is actually a very simple piece of kit fitted in car (or on a person for more general sports timing). The basic principle is not massively dissimilar to how a contactless bank card functions.

steve-V8s

Original Poster:

2,920 posts

259 months

Sunday 14th May 2017
quotequote all
Thank you for the ISO standard, that will be a good starting point.