I think the problems with a system like that would be first of all the speed of the passing cars, do people buzz through toll booths at 75MPH? Secondly, unlike toll booths and railway tracks, these cars could be coming through the timing point at a number of different angles relative to the beacon, which would make the reading of barcodes very difficult. -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of John Ferrell Sent: Wednesday, 17 March 2004 1:25 PM To: PICLIST@MITVMA.MIT.EDU Subject: Re: Identifying cars Railway cars & turnpike toll booths use bar codes in the US. John Ferrell http://DixieNC.US ----- Original Message ----- From: "Liam O'Hagan" To: Sent: Tuesday, March 16, 2004 8:04 PM 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? > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu