>-----Original Message-----
>From: Alan B. Pearce [mailto:A.B.Pearce@RL.AC.UK]
>Sent: 17 March 2004 09:20
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [EE]: Identifying cars
>
>
>>>A 2 foot by 3 foot barcode should be readable from several feet, no?
>>
>>Railways use these. Readable from a  distance
>
>I thought the US railways had tried these and given them up,
>as the dirt needed to be washed off on a very regular basis to
>get reliable reading. Maybe they have improved the reader
>technology to where the dirt is less of an issue, I know there
>is optical recognition technology that can read number plates
>despite great mud splats on them. I believe Australia uses
>this type of technology to try and keep truckers speeds and hours down.

Not to mention automated speed ticket issuing on certain UK motorways (SPECS
system)!

The bar code system is inherently flawed for the OP's situation.  If the bar
codes are on the sides of the cars, then they can be partialy obscured by
cars next to them.  If the bar codes are on the roof, the scanner has to
cover the entire width of the track somehow.

Model cars use RFID tags for lap timing and seem quite reliable.

Regards

Mike




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