Why don't you make it with RF instead of IR?



Mauricio D. Jancic
Janso Desarrollos - Microchip Consultant
www.janso.com.ar
info@janso.com.ar
(54) - 11 - 4542 - 3519
Lugones 3238 "B" - C1430ECN
Capital Federal
Republica Argentina
MSN: jansodesarrollos@hotmail.com

>>-----Original Message-----
>>From: pic microcontroller discussion list
>>[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Liam O'Hagan
>>Sent: Martes, 16 de Marzo de 2004 22:04
>>To: PICLIST@MITVMA.MIT.EDU
>>Subject: [EE]: Identifying cars
>>
>>Howdy everyone, a question on the best solution to this
>>particular challenge.
>>
>>I'm a member of a car club, and we often have track days
>>where we're timed around a racetrack. Currently the timing
>>consists of people with stopwatches clicking the button when
>>they see a car go past.
>>
>>Needless to say this is pretty inaccurate and not very reliable.
>>
>>Recently someone asked me if I could make a timing system,
>>using a transmitter on each car (as cheap as possible) and a
>>"beacon" that would detect the passing of the car, ans also
>>identify the car.
>>
>>I've thought of 2 possible solutions and would appreciate
>>feedback on what which is the most suitable, and reliable,
>>and whether anyone has any better ideas...
>>
>>The first solution would consist of an IR led on each car,
>>flashing at a discrete frequency, or even flashing a
>>predetermined "ID" code. A beacon would sit by the side of
>>the track at the timing marker and count pulses, identifying
>>each car in turn. In this case the beacon sees the car pass.
>>I thought initially of using a discrete micro on each car,
>>but it would be overkill. A 555 based timer would be easier
>>and cheaper...
>>
>>This has the advantage of being reasonably cheap to
>>implement, and it's easy to have a different frequency or
>>code for all of the different cars (about 50 different cars
>>per event, but only 8 on the track at any one time)
>>
>>Another option is to have an IR transmitter on the beacon,
>>and an IR receiver on the car. The car would also have a RF
>>transmitter, so when the car sees the beacon pass, it
>>identifies itself via RF. This would be more expensive, but I
>>think more reliable.
>>
>>The range from the beacon to the car would be 5 - 20 metres
>>(15-60 feet), depending on what line they take through the
>>corner. Speeds at this point of the track are generally 70 -
>>120km/hr (45-75 MPH)
>>
>>The angle between the beacon's line of sight and the path of
>>the car would ideally be 90 degrees, but knowing some of the
>>drivers this could vary considerably!
>>
>>The software and timing will be handled by a PC attached to
>>the beacon (or communicating to the beacon through RF again)
>>and displaying the times. I've done that part, just need to
>>handle the detection and identification of the cars now...
>>
>>Any ideas anyone?
>>
>>--
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>>

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