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...
On Wed, Mar 17, 2004 at 12:04:08PM +1100, Liam O'Hagan wrote:
> 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.
Hmm... sounds like more serious racing than I do. I'm an autocrosser doing Solo I, with only 1 (maybe 2, but no overlap) car(s) on the track at a time. I built some basic timing equipment for us, just IR tripwires to detect a start/stop condition.
> 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.
I like this method better. I'm not exactly sure what kind of racing you're doing, but is it possible to have two or more cars near the beacon at one time? I could see that introducing complications into the system.
Good luck, keep me posted on the progress. If I decide to get into higher speed stuff I'll probably end up being volunteered to do the timing equipment too. :)
Some of the guys are pretty serious, some have dedicated race cars, others
have spent $30000 on suspension alone, some (like me) just go there in their
stock car to have fun in a safe environment. The track is "Wakefield Park"
about 2 hours out of sydney
(http://www.wakefieldpark.com.au/site/frameset.cfm)
and it's a very safe track. There's absolutely nothing to hit!
We do have up to 8 cars on the track at once, but everyone is grouped by
similar laptimes and sent out at intervals that minimise passing. It's more
of timed single car sprints rather than wheel to wheel fender bender
stuff... Only 1 car has been damaged in 12 years of racing, and that was a
serious racecar late last year, a volvo 240 turbo that is 6 seconds a lap
quicker than my MX5. He had the front suspension collapse mid corner,
leaving the car on it's side. Fortunately it had a full cage and he was ok,
and since he owns a volvo wrecking yard, he just put all the good bits into
another shell and was back racing the next month!
Anyway, back to the timing system, I am leaning towards option 2 as it
appears far more reliable, less reliant on angles and speed of passing than
IR. IR transmitter modules are pretty cheap so it shouldn't be ridiculously
expensive...
> 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.
=== Andrew Warren -- EraseMEaiwspam_OUTTakeThisOuTcypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation
Am Mittwoch, 17. März 2004 02:04 schrieben Sie: {Quote hidden}
> 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
> @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu
I can see a problem... what if two cars do pass the finish line nearly at the same time just with a difference of less than a car length? I tell you, no IR method from either the right or the lift side, or even both will work.
You need to detect a passing car from over or under the track!
So the easiest and cheapest solution that comes into my mind now is to place a frame on the finish line. this frame holds a set of IR diodes in place over the track. The cars will be equipped with IR recivers turned upwards and RF transmitters to send the ID signal. (the IR recivers must be placed at the front of all cars, so they're all at the same place relative to the car, to be fair.)
When a car passes the frame and catches the IR signal it will send its ID signal via RF. This signal can be catched up by a computer that does all the needed calculations and processing. The RF ID circuit can be a cheap digital circuit connected to a cheap RF transmitter module.
A more advanced and professional method would be to put RFID's under the cars and the reciver units under the track. The powering reciver units hafe to be powered very low, to limit their range to the finish line. Everytime a car passes the line its RFID get's powered by the reciver and sends its ID signal back. This ID signal gets a time stamp when recived and then you have all needed data for processing...
On Wed, 17 Mar 2004 12:48:00 +1100, Liam O'Hagan wrote:
> Some of the guys are pretty serious, some have dedicated race cars, others
> have spent $30000 on suspension alone, some (like me) just go there in their
> stock car to have fun in a safe environment. The track is "Wakefield Park"
> about 2 hours out of sydney
> (http://www.wakefieldpark.com.au/site/frameset.cfm)
> and it's a very safe track. There's absolutely nothing to hit!
>
> We do have up to 8 cars on the track at once, but everyone is grouped by
> similar laptimes and sent out at intervals that minimise passing. It's more
> of timed single car sprints rather than wheel to wheel fender bender
> stuff... Only 1 car has been damaged in 12 years of racing, and that was a
> serious racecar late last year, a volvo 240 turbo that is 6 seconds a lap
> quicker than my MX5. He had the front suspension collapse mid corner,
> leaving the car on it's side. Fortunately it had a full cage and he was ok,
> and since he owns a volvo wrecking yard, he just put all the good bits into
> another shell and was back racing the next month!
There's a saying in SCCA racing here in the states... "Never take
anything to the track you're not willing to leave there!" ;-)
Matt Pobursky
Maximum Performance Systems
(and crew for a tired old Formula Ford)
Also it appears to require installation below the track surface, I'm not
sure the circuit owners would appreciate us digging up their rack. We also
race at about 4 other tracks locally so we'd need a system for each...
Good point about simultaneous passing of cars, the track in question does
not have any gantry or bridge over the track unfortunately which will make
it difficult.
The way our timing operates is as follows:
The timing marker is placed about 1/2 way round the track. The car enters
the track from the pit area and has that 1/2 lap to warm up, on completion
of the session (4 laps), the car passes the beacon mid track and has 1/2 a
lap to cool down.
This has the fortunate benefit that we can place the beacon in the middle of
a corner mid track, rather than on the straight where passing would be more
prevalent. This would minimise the problems associated with cars passing on
the beacon, and this, coupled with the second method of detection using RF,
would mean that we wouldn't have much problem with missed cars.
Perhaps a tall beacon, pointing down at the track at 45 degrees or so, and
with a 'tall' IR swathe would paint the whole track and allow detection of
simultaneous cars?
Am Mittwoch, 17. März 2004 03:15 schrieben Sie:
> Where's the fun in that!
>
> Also it appears to require installation below the track surface, I'm not
> sure the circuit owners would appreciate us digging up their rack. We also
> race at about 4 other tracks locally so we'd need a system for each...
>
Am Mittwoch, 17. März 2004 03:15 schrieben Sie:
> Good point about simultaneous passing of cars, the track in question does
> not have any gantry or bridge over the track unfortunately which will make
> it difficult.
Well, I first thought you're talking about RC cars...
forget the frame, the RFID could still work... you could just lay a flat wire over the track that emits RF which triggers the RF transmitter in the car to send the ID signal...
Am Mittwoch, 17. März 2004 03:27 schrieben Sie:
> Most cars get a lot of wheelspin around this particular corner, which wiuld
> chew up the cable pretty quickly...
Hm... then we need a flat sourface, like a foil of plastic with conductive layers on it... the foil needs a surface that is big enough to stay in position, so to withstand the forces...
Such a system is problematic because of the two limitations, that it isn't your track and you want to keep it cheap...
What about some of the automated toll booth technology?
I'm not sure what they use - just an idea for others to expand on.
Then again - they might not have the positional accuracy you want.
Am Mittwoch, 17. März 2004 16:25 schrieben Sie:
> What about a strip of aluminium duct tape for the antenna - cheap,
> replaceable and should last quite a while.
>
> Regards
>
> Alex
>
Not a bad idea!
On Wed, 17 Mar 2004 12:48:00 +1100, Liam O'Hagan wrote:
> Some of the guys are pretty serious, some have dedicated race cars,
others
> have spent $30000 on suspension alone, some (like me) just go there in
their
> stock car to have fun in a safe environment. The track is "Wakefield
Park"
> about 2 hours out of sydney
> (http://www.wakefieldpark.com.au/site/frameset.cfm)
> and it's a very safe track. There's absolutely nothing to hit!
>
> We do have up to 8 cars on the track at once, but everyone is grouped by
> similar laptimes and sent out at intervals that minimise passing. It's
more
> of timed single car sprints rather than wheel to wheel fender bender
> stuff... Only 1 car has been damaged in 12 years of racing, and that was
a
> serious racecar late last year, a volvo 240 turbo that is 6 seconds a
lap
> quicker than my MX5. He had the front suspension collapse mid corner,
> leaving the car on it's side. Fortunately it had a full cage and he was
ok,
> and since he owns a volvo wrecking yard, he just put all the good bits
into
> another shell and was back racing the next month!
There's a saying in SCCA racing here in the states... "Never take
anything to the track you're not willing to leave there!" ;-)
Matt Pobursky
Maximum Performance Systems
(and crew for a tired old Formula Ford)
> Make a giant sized magnetic barcode and stick one on the side of each car.
> A 2 foot by 3 foot barcode should be readable from several feet, no?
Railways use these. Readable from a distance
______________
Cars have receiver which sees a beacon (eg laser line).
Car then transmits it's ID and a local clock AFTER passing line for several
iterations with random pause between. Could be done with eg IR.
Could have several trigger points on track.
Needs uP in car.
Needs timing in car.
Needs receiver (one per trigger point)
Not overly complex.
As long as car clock is stable enough for period of race the absolute clock
value is irrelevant - it self calibrates after the first reading.
Tlap = Clock_now - clock_then.
100 f/s = 10 ms resolution for 1 foot timing.
= 1 mS for 0.1 foot timing
Each car just passes the beacon and announces that it has finished a lap via
RF to a beacon. That beacon notifies the host PC. The host PC keeps track of
lap times for all cars.
Since the time taken to announce the passing of the beacon and notify the
host PC will be constant for each car, the timing should be accurate. I have
a timing class for the PC that is capable of timing easily to 6 decimal
places so no problems with 1ms resolution there.
Another benefit of this approach over the IR method will be that the micro
can be in low power or sleep mode for most of the lap, and wake up /
transmit when the beacon is passed. Good for battery life for the cars that
have their interiors stripped and have no cigarette lighters for power
supply...
Since there are a lot of different types of cars competing, the on-car
hardware may not be the same height for each car, so I would need a tall,
narrow beam of IR to be sure of triggering each car.
Another advantage of using RF over IR would be that the in car hardware
could announce a low battery condition, which would be handy to allow
replacement before the battery dies.
I've also just discovered that futurlec have started operations in
Australia! Their prices (in AUD) are about 1/3 of my local distributor for
micros :)
>>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.
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>-----Original Message-----
>From: Alan B. Pearce [KILLspamA.B.PearcespamBeGoneRL.AC.UK]
>Sent: 17 March 2004 09:20
>To: EraseMEPICLISTEraseMEMITVMA.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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>Model cars use RFID tags for lap timing and seem quite reliable.
I suspect that this is how the formula one and similar race cars do it as
well. However in these cases I suspect that it is a permanently transmitting
beacon seeing power is available.
For the OP, is it not possible to have a slot cut in the track to drop a
wire receiver aerial into, or is it a dirt/cinder track? If a hard surface
then potentially any other uses of the track would probably also welcome
having the receiver loop permanently embedded, even if each club had to own
its own timing gear (maybe an opportunity to hire the gear you own).
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> >Model cars use RFID tags for lap timing and seem quite reliable.
>
> I suspect that this is how the formula one and similar race cars do it
> as well. However in these cases I suspect that it is a permanently
> transmitting beacon seeing power is available
I believe all race tracks are now based on this loop system
Click through English/Europe/Oval Track Racing to get to a page
with a How It Works link (nice big picture at the end of it all)
I looked into it just out of interest last year. This isn't the company I
remember looking sat (Dutch I think it was) but the principle's the
same. ISTR there were other loops for something that could be up
to 50m long. Which isn't that long when you're doing 90+m/sec in
a CHAMP or IRL car
> For the OP, is it not possible to have a slot cut in the track to drop
> a wire receiver aerial into, or is it a dirt/cinder track? If a hard
> surface then potentially any other uses of the track would probably
> also welcome having the receiver loop permanently embedded,
> even if each club had to own its own timing gear (maybe an
> opportunity to hire the gear you own)
That's what I was thinking. Rather than messing up someone's track,
you're actually improving and increasing the value of it. Surely a narrow
slot or two isn't THAT objectionable. There's a certain overhead for
the hardware, whichever way you go, may as well make the one that's
going to work. A couple of lads at the weekend with a cutting disc to
make 1/4" slots and a pot of asphalt to patch it up ?
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Rather than IR, could you use an ultrasonic "transmitter" on each car,
tuned to a different frequency? A sensor could pick up the approaching
vehicle, identify it based on its frequency, and the doppler shift would
tell you the precise moment it passed the finish line.
Ambient noise is the only obstacle I can think of....
Perhaps using a doppler shift from a light source? again, frequency to
identify vehicle, and shift to detect time....
Just my $0.02 US, adjusted for inflation.....
--Joe Jansen
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> > You could just buy a system from AMB... http://www.amb-us.com/
>
> Where's the fun in that!
Presumably, it'll be more fun to drive your car at the track
than to spend all your time there debugging a homebuilt timing
system. I'd expect it to take at least a year to produce a
barely-usable system.
> Also it appears to require installation below the track surface,
> I'm not sure the circuit owners would appreciate us digging up
> their rack. We also race at about 4 other tracks locally so we'd
> need a system for each...
Actually, I think they WOULD appreciate it.
AMB's system is more-or-less the standard; once installed, its
presence benefits the track owner.
-Andy
=== Andrew Warren -- TakeThisOuTaiwKILLspamspamcypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
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=== Cypress Semiconductor Corporation
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To measure to 1msec you need to define a virtual barrier width
corresponding to 0.5msec for your measuring system, constant across the
entire road. You could use an optical method I think. At 300kph 0.5msec is
4 cm or so so you will have to use something with a real narrow field of
view. The car id can be done 'later' or 'before', not necessarily at the
same location where the timer is. And optical may not be so good if there
is a cloud of dust from the previous car. I would be tempted to do
something with a microwave beam across for lap time and another 'in front'
to read speed (doppler) and activate a challenge/response type gizmo in
the windshield area of the car. This does not solve the problem of several
cars passing side by side. I have little experience with microwave but
from what I know I think it would work. Each car would have a radar
detector (of commercial manufacture) and this would be wired to activate a
tag transmitter, perhaps on 433 MHz. The beams produced by 'door opener'
type microwave sensors are suitable for making barriers up to 15 meters
wide (using two units).
Peter
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I guess it's too much to hope that there's a drain or duct line under the
circuit near the appropriate location? (For an RFID Loop)
Why not have the unit on the cars do the timing, triggered by a beacon at
the chosen spot, and then transmit the info to a PC. It could do the
transmit thing several times to minimise (data) collision oppertunities. A
32kHz watch crystal should be more than adequate for timing.
I see more difficulty in getting the beacon to trigger the device
appropriately at an accurate location.
Richar P
"Alan B.
Pearce" To: .....PICLISTRemoveMEMITVMA.MIT.EDU
<A.B.Pearce@RL cc:
.AC.UK> Subject: Re: [EE]: Identifying cars
Sent by: pic
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17/03/04 22:49
Please respond
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>Model cars use RFID tags for lap timing and seem quite reliable.
I suspect that this is how the formula one and similar race cars do it as
well. However in these cases I suspect that it is a permanently
transmitting
beacon seeing power is available.
For the OP, is it not possible to have a slot cut in the track to drop a
wire receiver aerial into, or is it a dirt/cinder track? If a hard surface
then potentially any other uses of the track would probably also welcome
having the receiver loop permanently embedded, even if each club had to own
its own timing gear (maybe an opportunity to hire the gear you own).
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The problem I face here is unit cost, adding more and more hardware to the
in-car device will increase the overall cost of such a system dramatically.
The clubs that are looking at purchasing or funding this system don't want
to spend more than approx $1200 for 25 in car beacons, plus trackside and
timing room hardware.
This limits me to about $30 - $35 per unit for the in car beacons, which I
can do using IR and RF. I think a system such as this, with the IR telling
the RF when to transmit, will be sufficiently accurate and reliable, far
more so than the current person-with-stopwatch system. I also checked and
our insurance coverage for the event prohibit us from modifying the track
surface in any way, especially mid corner...
I definitely cannot install any permanent hardware or make structural
changes to any facilities at the track.
I'll investigate my options with this, I'll let the list know when a
solution is reached :)
FYI, there's a device that's used in a lot of road races ("foot races")
called a "ChampionChip". It;s a small transponder that is typically tied to
the shoelaces, and detected at the finish line. The company is at http://www.championchip.com - they may or may not have a solution that would be
appropriate to auto events.
Jim
> Thanks for the ideas everyone!
>
> The problem I face here is unit cost, adding more and more hardware to the
> in-car device will increase the overall cost of such a system
dramatically. {Quote hidden}
> The clubs that are looking at purchasing or funding this system don't want
> to spend more than approx $1200 for 25 in car beacons, plus trackside and
> timing room hardware.
>
> This limits me to about $30 - $35 per unit for the in car beacons, which I
> can do using IR and RF. I think a system such as this, with the IR telling
> the RF when to transmit, will be sufficiently accurate and reliable, far
> more so than the current person-with-stopwatch system. I also checked and
> our insurance coverage for the event prohibit us from modifying the track
> surface in any way, especially mid corner...
>
> I definitely cannot install any permanent hardware or make structural
> changes to any facilities at the track.
>
> I'll investigate my options with this, I'll let the list know when a
> solution is reached :)
>
FYI, there's a device that's used in a lot of road races ("foot races")
called a "ChampionChip". It;s a small transponder that is typically tied to
the shoelaces, and detected at the finish line. The company is at http://www.championchip.com - they may or may not have a solution that would be
appropriate to auto events. Jim
> Thanks for the ideas everyone!
>
> The problem I face here is unit cost, adding more and more hardware to
> the in-car device will increase the overall cost of such a system
dramatically. {Quote hidden}
> The clubs that are looking at purchasing or funding this system don't
> want to spend more than approx $1200 for 25 in car beacons, plus
> trackside and timing room hardware.
>
> This limits me to about $30 - $35 per unit for the in car beacons,
> which I can do using IR and RF. I think a system such as this, with
> the IR telling the RF when to transmit, will be sufficiently accurate
> and reliable, far more so than the current person-with-stopwatch
> system. I also checked and our insurance coverage for the event
> prohibit us from modifying the track surface in any way, especially
> mid corner...
>
> I definitely cannot install any permanent hardware or make structural
> changes to any facilities at the track.
>
> I'll investigate my options with this, I'll let the list know when a
> solution is reached :)
>
> -----Original Message-----
> From: pic microcontroller discussion list
> [EraseMEPICLIST@spam@MITVMA.MIT.EDU]
> Behalf Of @spam@Richard.Prosserspam_OUT.....POWERWARE.COM
> Sent: Thursday, 18 March 2004 7:32 AM
> To: spamBeGonePICLISTEraseMEMITVMA.MIT.EDU
> Subject: Re: [EE]: Identifying cars
>
>
> I guess it's too much to hope that there's a drain or duct line under
> the circuit near the appropriate location? (For an RFID Loop)
>
> Why not have the unit on the cars do the timing, triggered by a beacon
> at the chosen spot, and then transmit the info to a PC. It could do
> the transmit thing several times to minimise (data) collision
> oppertunities. A 32kHz watch crystal should be more than adequate for
> timing.
>
> I see more difficulty in getting the beacon to trigger the device
> appropriately at an accurate location.
>
> Richar P
>
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> FYI, there's a device that's used in a lot of road races
> ("foot races")
> called a "ChampionChip". It;s a small transponder that is
> typically tied to
> the shoelaces, and detected at the finish line.
That chip is used a lot in my country, I think all major running evens
use it. Used it myself three times, very small and very easy. But I
think at least this particular chip has a very short range, you must
realy walk over the rubber that contains the sender/receiver to be
detected.
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