Sure Path

[Horton]

@jayski yeah yeah that's a typo. whatever.

[jpwhit]

In simple terms, there are a lot of factors that contribute to GPS error and therefore limit accuracy, but the errors tend to be consistent over a fairly small geographic area.

 

The purpose of the base station is to essentially create a real time way to measure these inaccuracies. That's accomplished because the base station must be stationary at a known set of coordinates. You simply compare the coordinates being reported by a GPS receiver at the base station location with the known position of the base station and you get a reading of the error at that exact point of time at that exact location.

 

By sending these real time measurements of the errors from the base station to the rover, and making the assumption that the error at the rover location will be exactly the same as at the base station, you can use the data from the rover to "correct" the errors at the rover. This results in a highly accurate position reading calculated by the system at the rover.

 

The further the rover is from the base station, the less true the assumption that the error at the base and rover are exactly the same becomes. Hence, the accuracy of the position computed at the rover decreases by an equal amount.

 

So, when someone says a base station within 25 miles is good enough, they are assuming a certain accuracy for "typical applications" is good enough. What really matters in this case is precisely how much accuracy is required by Sure Path to be useful. And that in itself may be a somewhat subjective question. Of course, the more accurate the better. Another way to think about it, when Sure Path says you deviated off the centerline by x amount. Some of x is how much you were actually off, and some amount is GPS inaccuracy.

 

[rayn]

@MichaelGoodman that is what I would have thought. But according to the map on the mass Dot website https://macors.massdot.state.ma.us/SBC —Closest one is in Westboro. Any info on other networks you are referring to would be helpful.

[MichaelGoodman]

@rayn you may want to check with the Town engineers or a local engineer the

map for Plymouth just shows one (which is right near my pond) but I checked

with the engineer I use and he use these system he told me Plymouth has three

maybe there are main stations and sub-stations be worth checking.

[Jtim3032]

Sorry guys, not been following recently...

 

Yes, a Sure-Path rover works with any NTRIP base station as well as the dedicated Sure-Path one. The US network of base stations is known as the CORS network and each State has its own network which forms part of the larger CORS network. Some states provide access for free, others not.

 

The cool thing about these networks is that all the base stations are linked and there is usually a service available that is a "networked solution". What they mean by that is that if the rover regularly sends its position back to the base network, instead of just providing corrections from the nearest base (which may still be tens of miles from the rover) the network creates a "virtual" base station which gives corrections as if it were close to the rover, thus maintaining accuracy.

 

As people have said, Jerry has been doing a lot of testing in Florida with some pretty good results so far.

 

There are some other considerations to take into account such as whether the network supports Beidou and Galileo satellite constellations in addition to the usual GPS and GLONASS. If just the latter two, then this halves the number of possible satellites that can be used and as usual, it is the more the merrier for RTK GPS systems.

 

For the nerds, there is also tectonic plate movement to consider. This could determine how often you need to remap the course. The CORS network uses the NAD83 data set and Sure-Path uses WGS84. Some states such as Florida are only moving a few millimetres per year where as California.... :smile: Geodetics is a whole science in itself.

 

James

[Jtim3032]

@MichaelGoodman price for Sure-Path rover is half the cost of the full system.

[Jtim3032]

@rayn find out if there is a VRS (virtual reference station) service available. If so, it doesn't matter how far from a physical station you are.

[Jtim3032]

@Chad_Scott @paul

 

I originally started off using local radio modems. A bad experience near a busy airport whose radars completely obliterated the radio modem's signals persuaded me to start considering using cellular coverage instead and I found that in most circumstances it was far more reliable. Sure-Path will work with radio modems too but decent ones are expensive. My preferred recommendation now is to setup a local WiFi network using Ubiquiti or similar units. This can also solve other problems such as boat camera to shore transmissions which can interfere with other radio modems. If all the tech in the boat is on the same communication system, there is no likelihood of one interfering with another.

[liquid d]

Or you could just buy the whole system, make the guy some money, and when you go to someone else's site, you bring your whole system and not worry about all the other stuff!

[skierjp]

@liquid d ?I was waiting on someone to suggest that. Freaking skiers are just cheap and they’re the ones complaining about the sport slipping away.

[lpskier]

Isles of Lake Hancock connected to a base 30 miles away. They also had a SP base station on site connected to a second phone in the boat. Because of the Florida DOT system resulting in the virtual on site base station, there were no deviations between the phone connected to the DOT base 30 miles away and the phone connected to the SP on site base. And it’s free.

[Jtim3032]

A small clarification....proximity to a physical base station is not really relevant when using the VRS (virtual reference station) solution. The system creates a virtual base using correction data from ALL the active physical stations in the network. Time will tell as to whether the VRS solutions are reliable from different providers.

[Milford]

We have 30 owners on our 2 lake site and are hoping to get 6-8 of them to go in on a base station and buy rovers for each boat. Cuts the price per owner down to around $1200 each and gives us a whole lot of control without any hassle. The price of knowing your getting great ride and that your fellow ski partners and neighbors are investing in becoming the best boat drivers possible....priceless!

[Horton]

@milford wait until Parsons has his rover for a week or two the move the base station about 3 inches

[teammalibu]

@Horton i did that to @jayski i just turned the pylon mount sideways while he was driving.

 

[MISkier]

From the 2021 Proposed rule changes:

 

PROPOSAL 17: 15.06D1a-d

1) Delete the steps (15.06D1a thru d) in AWSA Rule rules for EC Video and refer to the IWWF Rule Book for EC Video.

 

2) Added a statement that we can use an Approved Boat Path Measurement System as stated in IWWF Rule book.

 

15.06 Technical Requirements

 

D. Slalom Requirements:

 

1. End-course video or Approved Boat Path Measurement System:

a. End Course Video and/or Approved Boat Path Measurement System must be used in Class E/L/R tournament per IWWF specifications Rules.

 

a. End Course shall be recorded in the Slalom event for all passes. A rigidly mounted video camera shall be operated from a point on the centerline on at least one end of the slalom course, adjusted to show all of the boat guides in clear focus and equipped with sufficient power to display the far entrance/exit gate occupying at least 1/6th of the full width of the screen (1/3 width or larger is recommended).

 

b.It is recommended that a radio receiver be placed by the recorder so that all radio transmissions are recorded on the audio track, and that the skier's name and speed and/or line length be announced on each pass, and the actual times recorded by the official timing devices also be announced.

 

c. A black 5cm (2”) (approximately) wide strip on the middle of the windshield will be used to show up on the end course video. If the boat already has a visible center mark on the windshield this is not necessary. A visible mark would be a center seam between two halves of the windshield or a center swing out window that would have vertical seams on either side of center. The mark, if required would only need to come up approximately half way to the top of the windshield, but be clearly visible in the end course video.

 

d.A mark or small post on the top of the windshield that is visible in the end-course video camera (both directions) shall be placed 20 cm from the center of the windshield on both sides of the center to aid in the determination of the 20 cm deviation (for onsite video review).

[disland]

If you use the Boat Path measuring system and no end course video what do you send in with the TC report?

[MISkier]

I thought I heard something about an integration into the scoring system. I haven't seen anything specifically confirmed nor any details, but it seems that it would need to link the path data to the pass/skier somehow.

 

@Jtim3032, do you have any details on how the submission of path data will likely transpire?

[Chad_Scott]

It does tie into the waterski connect system and at the end of the event you can download all of the data from the event. Much quicker than looking through hours of end course video

[MISkier]

Is there any video demonstration of how that works and what the screens look like? Would be very informative to have some YouTube videos on this particular function.

[mbabiash]

I feel like both should be used. Who’s to say that people won’t just turn in random data from sure path. With no video, how fin you ensure that the data corresponds with a particular skier/tournament.

Cheaters will cheat.

[Horton]

@mbabiash with your line of thinking who's to say they aren't turning in video of practice? I believe the future state of sure path is that the data is going up to the cloud real time and there is a timestamp on every pass. furthermore that data can be commingled with scoring so you can see which pass is which skier and line length.

 

I'm pretty sure all the infrastructure for this already exists but I have not personally seen it work.

[teammalibu]

@Horton when you send in end course video of a tournament you also include the Slalom Detail Report that is synced to the time on the video. That report includes skier time and score for every pass also list the driver!

[disland]

The Russians can hack the pentagon, if you want to cheat that bad be my guest

[Horton]

@teammalibu yeah you're supposed to. do you think everybody does?

[Jtim3032]

@MISkier we have been working for some time on a data link between Sure-Path and the two main scoring systems, WSTIMS and Lion. The link is via an online server. In tournament, this server can record all the boat path data as it goes through. Since the scoring software will be providing the driver name, skier name, boat speed, rope length etc to Sure-Path (and embedded in the Sure-Path data file), there is no more chance of mismatches than there has ever been.

 

@mbabiash Also, we are not doing away with end-course video yet. It still has to be recorded and submitted when required. The main difference is that IF there is a Boat Path Measurement System in use, the end-course does not have to be monitored live by a judge. Instead, Sure-Path (or the BPMS in use) will be sending the data back to an application in the judging area which gives instant guidance on re-rides. The data also goes into the scoring program.

 

We are about to release a version of the rover software which implements the new rule 8.15 and the judging application to go with it.

 

As soon as I get time, I will be putting more information on the web site.

[lpskier]

@Jtim3032 What device will we need in the judges’ tower?

[blakeyates]

@skierjp, I was thinking the same thing. The majority of skiers make an above average income and they look for ways to get things super cheap. The bad news is when the system doesn't work right, they wonder why? If we're going to use this technology let's do it right. If we can't afford it, then status quo will continue.

[Jtim3032]

@lpskier we have a Windows application that can receive and display the Sure-Path summary screen immediately after the pass. If linked to the scoring program, the timing data goes there also.

[disland]

@Jtim3032 So no more calling in times over a radio? That would be awesome

[BS74]

Who pays for these things to be used in tournaments? Do you need one for each boat?

[Not_The_Pug]

@BS74 mostly being purchased by drivers who want to be better and get a good ride in practice. Our lake bought one base and so far individuals have purchased 5 rovers. Any other members that want to add it to their boat can just buy a rover. Two of the individuals that bought the system are promo boat owners, so we will have the use for tournaments.

[skierjp]

Not real sure a Promo Team Member is going to offer up their equipment for free. After all, they had to pay for it.

[Milford]

@skierjp I would think that if someone has ponied up the $$ to buy a Sure Path system and they were going to be at a tournament with a base station nearby, I can't imagine them not wanting to use it in the tournament. It's not like a boat that depreciates with every hour used. Why not make the tournament as good as it can be?

[lpskier]

I have seen two tournaments rent Surepath. $200-300.

[Jtim3032]

@disland yup, no more calling in the times :)

@lpskier interesting....as with virtually all software, renting out its use commercially is strictly against the licence agreement.

[dchristman]

Ruh-roh

[skierjp]

Maybe renting the device is the wrong term. If a TC has it as part of his setup for a tournament you can guarantee the tournament site will be charged.

[Jtim3032]

@skierjp yes, your statement may well be true. But it doesn't mean that it is legal ;) . Use for homologation could be seen as being for the TC's personal use. Use for boat lane tracking in the tournament could be "leasing" if charged for. For more information on our licensing policy, see here sure-path.com/leasing-sure-path.html

[disland]

Can a rover connect to an iPhone acting as a wifi hot spot?

[Horton]

@disland yes that is what we do.

[skiinxs]

@disland Yes, but I found it is much more reliable to use a cell data card. It was also a pain to have my cell dedicated to the boat, especially when someone else was driving. Here is a tip that may save you a lot of time. After deciding to switch from cell wifi hotspot to dedicated data, I added a line to my AT&T account for the rover. (AT&T is the only carrier that has service at my lake.). After several weeks and countless hours with AT&T tech support, I gave up on AT&T as they were never able to get their sim cards (tried several) to work in the rover. James suggested that I try Red Pocket mobile. With Red Pocket, their card worked perfectly with no hassle, simple online setup, and cheaper than an additional line on my AT&T account. ($15.49/mo including taxes for more data than you ever need with Sure Path and an extra phone line to boot) The really funny part is they resell service on the AT&T towers.

[Jtim3032]

@disland in theory yes but results of hotspotting seem to be mixed. Usually it works fine but sometimes seems patchy. I would normally suggest starting using a hotspot and only get a sim card if it becomes necessary.

[lpskier]

My experience with using my phone as a mobile hot spot was less than optimum. Get the SIM card.

[Jtim3032]

@skiinxs thanks for the input. I think the extra level of abstraction is all that is needed to stop or at least inhibit the usual market protection practices built in to AT&T's system. AT&T are not the only culprits. Verizon I believe are the worst. Another trick is to activate a native AT&T sim in a genuine AT&T phone. Then switch the sim to the Sure-Path phone. The AT&T scanning for "none genuine" unlocked phones seems to be periodic and so eventually the card may stop working again. This happened to another customer and just switching the card out to another phone and then back again cured it. I could start a good business shipping out UK sim cards. It's actually cheaper to use one of those in the US than a native US card!

[disland]

@Jtim3032 I live on my lake, so if I deploy an outdoor wifi AP such that I have wifi coverage on the lake that will work also correct?

[Jtim3032]

@disland yes it will. Ideally the AP should have line of site if the boat whilst in the course. How far the boat will be at its furthest point will determine just how big you have to go with hardware.

[Skirvind]

Yes the rover can run in wifi

[Horton]

@Skirvind you have wifi that covers your whole lake?

[Skirvind]

@Horton I do have wifi coverage over the whole lake. I ran surepath all summer using it. I can share my setup with you if you want.