Timing equipment, when there are large distances involved.

Just wondering how this is done in different organizations. Our local hillclimb club, uses a computer to keep time. A starter counts down from 3-2-1 go, somebody hits a button to start time at that moment. At finish they cross a timing light, and a time is generated. Hand held radios do not often work because of line of sight considerations with mountain terrain. So the club uses both hand helds and a hard wired radio system. They run this wire up the hill for each event....it has only two strands of wire. Just wondering how one could use a timing light at the bottom, and one at the top and avoid adding more wire.

Rally must time in and time out with sync'd clocks, how do they maintain the sync?

In the old days of rally the lead car would check the watches at start and finish controls. At a hillclimb you only need synced clocks top and bottom. Start each car at a known time and record the time of day at the finish. Subtract and there is your time. Finish line only has to report to start the finish time. Software will do the rest. Using a radio tuned to WWV will keep the clocks in sync.

Nick

Not really addressing the question, but this seems like a spot where GPS could shine...

Clem

I had thought about sync'ing time via gps, as gps is a pretty cheap add on to any laptop pc

I run with the PHA and I'm not 100% sure how our timing works but I'll give it a whirl. We also use hard wired equipment and out longest hill is 2.3 miles. We use a rolling start and trip some kind of photocell(?) to start the clock and there is a similar device at the finish line. The starter enters the car number into the computer when you stage. We usually have 2-3 cars at a time on the hill (depending on the class). We have a Rahal Lola that runs with us occasionally and he gets a solo. If you want additional information, visit our forum. I'm sure there are people on there that have more knowledge than I do. It's at PHA Forum

I have helped set up the hill at Polish Mountian, we ran a wire up the distance of the hill for the finish photoreciver (something like a mile and a half of cable). I didnt help set up the start line, but my impression is that we ran a photoreciver to trip the clock start. The accuracy of the times would indicate that it was purely electronically driven.

I can get a concrete answer this weekend if you need one.

I would be curious to here the answer, so please ask. specifically were on the mountain the timing PC is placed(top, middle, bottom). How the photocells are connected to the computer.(if a hard line, what type of wire). Does that hardwire have any other duty(communications or anything else).

ClemSparks wrote: Not really addressing the question, but this seems like a spot where GPS could shine... Clem

No it's not. A GPS is nowhere near accurate enough to give quality times. If they turned out accurate to 1/10th of a second you'd be lucky. I have a very accurate GPS and I have to move a good 4-5 feet for it to register that I've moved at all, and that doesn't even take into account that the GPS will have to make an average of your time between points to guess where you are. Mine updates coordinates just over once a second.

GPS data is good for supplementing accelerometer and timer data but is a total joke at replacing either one.

For the record...the closest I've been to a GPS anything (knowingly) was while flying with my cousin once.

I know next-to-nothing about them. I wasn't saying that one could use a GPS thingie for this now/as-is...I was saying the technology of this stuff could be put to good use in this sort of situation...

that's all,

Clem

sachilles wrote: I would be curious to here the answer, so please ask. specifically were on the mountain the timing PC is placed(top, middle, bottom). How the photocells are connected to the computer.(if a hard line, what type of wire). Does that hardwire have any other duty(communications or anything else).

the computers were at the bottom. the hardline was something that looked like an ethernet cable, but i dont think thats what it was.

communications was via handheld wireless units (walkie talkies)(we had a repeater to help cover the top of the hill)

I think the idea was not to use GPS for position of the cars but for the timing. GPS works by the time differences of the signals from 3 or 4 sattelites so even a cheap GPS unit has an accurate clock.

]Not sure how that would help in this situation though when you are trying to measure very precise times.

GameboyRMH wrote:

ClemSparks wrote: Not really addressing the question, but this seems like a spot where GPS could shine... Clem

No it's not. A GPS is nowhere near accurate enough to give quality times. If they turned out accurate to 1/10th of a second you'd be lucky. I have a very accurate GPS and I have to move a good 4-5 feet for it to register that I've moved at all, and that doesn't even take into account that the GPS will have to make an average of your time between points to guess where you are. Mine updates coordinates just over once a second. GPS data is good for supplementing accelerometer and timer data but is a total joke at replacing either one.

you're correct, except where you're wrong.

yes, gps have a highest acuracy of 6-14 feet, but the clocks in them are synchronized every time you link up with the satellites.

What about wireless Internet? You could hook the start light up to a laptop through a USB, same with the finish, and then have both feed live to a website. Verizon Aircards would get you the nescessary connection speed, and the website could be pre-programmed with the cars in some sort of database. It would even let competitors see their times live. Just a thought, I don't think such a system exists yet.

How does Pike's Peak do it?

Pinchvalve, good thought. Unfortunately, the cell coverage at some of the hills we use wouldn't support that.

ClemSparks wrote: For the record...the closest I've been to a GPS anything (knowingly) was while flying with my cousin once. I know next-to-nothing about them. I wasn't saying that one could use a GPS thingie for this now/as-is...I was saying the technology of this stuff could be put to good use in this sort of situation... that's all, Clem

Carry a cell phone? just about every single one reports to the GPS sats. even if the GPS option isn't listed.

The club I autocross with has some type of wireless setup and it's used at the local hillclimb. Must be some type of radio transmitter as there is no cell phone reception at the top of the hill (dead zone ). I'll ask about it next weekend at the hillclimb since I have the last 2 corners and finish line where the timer is.

Strizzo wrote:

GameboyRMH wrote:

ClemSparks wrote: Not really addressing the question, but this seems like a spot where GPS could shine... Clem

No it's not. A GPS is nowhere near accurate enough to give quality times. If they turned out accurate to 1/10th of a second you'd be lucky. I have a very accurate GPS and I have to move a good 4-5 feet for it to register that I've moved at all, and that doesn't even take into account that the GPS will have to make an average of your time between points to guess where you are. Mine updates coordinates just over once a second. GPS data is good for supplementing accelerometer and timer data but is a total joke at replacing either one.

you're correct, except where you're wrong. yes, gps have a highest acuracy of 6-14 feet, but the clocks in them are synchronized every time you link up with the satellites.

Well the clocks in the GPS could make good timing devices...but then you'd need an optical sensor or something that trips when the the car passes, and then you'd basically have something like those radio-clock setups that store start and stop times.

You might ask the Chief of Timing and Scoring at the Big Bend Open Road Race They have to do it over a 60-mile course with lots of terrain between the start/finish lines.

No real time synchronization is needed between the start and finish lines. Start on a recorded time and finish on a recorded time. Subtract and you have elapsed time. If the clock at the top was 15 seconds fast compared to the one at the bottome, then every one would receive a time 15 seconds slower than actual but the compartative time would still be okay. Almost every performance rally runs this way.

RichardM wrote: No real time synchronization is needed between the start and finish lines. Start on a recorded time and finish on a recorded time. Subtract and you have elapsed time. If the clock at the top was 15 seconds fast compared to the one at the bottome, then every one would receive a time 15 seconds slower than actual but the compartative time would still be okay. Almost every performance rally runs this way.

problem with that is that if one clock actually runs faster, people that run later in the day will have slower times than people earlier in the day. and lets not forget how temp can affect things, ever heard of the palmdale bulge?