U-Blox 9 is now out, even more accurate than 8 and with cm accuracy. Will update my bluetooth dongle to this once I can get my hands on the chipset.
Select to expand quoteRoo said..
U-Blox 9 is now out, even more accurate than 8 and with cm accuracy. Will update my bluetooth dongle to this once I can get my hands on the chipset.
"Stand-alone u-blox F9 solutions robustly achieve meter-level accuracy. To achieve centimeter-level accuracy, u-blox F9 offers optional on-chip Real Time Kinematic (RTK) technology."
"Product samples will be available in the course of 2018."
Citations from the official announcement at www.u-blox.com/en/press-releases/u-blox-announces-u-blox-f9-robust-and-versatile-high-precision-positioning-technology
Select to expand quoteRoo said..
U-Blox 9 is now out, even more accurate than 8 and with cm accuracy. Will update my bluetooth dongle to this once I can get my hands on the chipset.
Thanks for the heads up Roo. 
It looks like the Ublox M9/F9 may be capable of PPP-RTK cm level positoning by default, and at consumer level prices, but exact model details are thin on the web so far.
It will be interesting to see what multi frequency capability does for Doppler speed accuracy.
It also sounds like there is a bit of a way to go in developing accessible, freely available correction data (State Space Representation -SSR)
via public broadcasting networks for many countries, Australia included, to take full advantage of the positioning accuracy that may be possible.
This clearly looks like another step closer the consumer accessible, cm level positioning accuracy. 
Select to expand quoteboardsurfr said..
Since the USB dongle has accuracy comparable to the GW-60 and provides accuracy estimates, it may be worth considering to have it as an "officially approved" device for GPSTC. ......It would be nice to get some feedback. If there's no general interest, I'll just pursue an ok to use it for GPSTC postings as a custom ublox-based device.
I have already raised with the GPSTC advisory group the fact that I am happy to recommend UBLOX based, UBX producing 10Hz and higher devices for approval on GPSTC. Extensive testing by Roo, Manfred, Gyro, Myself and others have completely satisfied me that the data is accurate, reliable and the error values are at least as good as other approved devices from well constructed ublox based custom devices. From my point of view, the only reason that they are not listed yet is that there are no production consumer devices available, and only a few custom built devices in use, and no one has asked for a particular device to be approved.
Sounding more interesting all the time, ublox9 on a Pi running ubuntu, would definitely get me in.
Select to expand quotedecrepit said..
Sounding more interesting all the time, ublox9 on a Pi running ubuntu, would definitely get me in.
It's great to see that ublox keeps improving the chips. It will be interesting to see what impact RTK (etc.) has on doppler speed accuracy. Taking just the numbers, cm accuracy still translates to position errors in the low percentage range (4 cm would be about 2% with 40 knot speeds at 10 Hz, more at lower speed or 18 Hz). That would be actually be worse to the accuracy that we can get from the GW-60 with good reception (+- 0.4 knots, 1% at 40 knots). But that's too pessimistic a view, since even now, with position accuracy in the meter range, the positional speeds are typically very close to doppler speeds. For some reason, though, I think that excitement about ublox9-ubuntu-pies will remain the exception 
.
Yes. It will be interesting to see how the use of more satellites and dual frequency affect Doppler accuracy. I don't think the RTK process will affect the Doppler directly.
It is interesting that in 2008, the WSSRC accepted a GPS (Trimble survey grade) with a proven measurement error of less than 10cm, but some time after 2009, they updated that to 5cm. The HDOP error amount is added to the distance measurement (500m/1NM) and the total time over that distance is taken as 500m/NM.
Looking at my recent results, the Doppler error over 10 seconds from the Locosys GW60 5Hz device worn on the wrist at around 40 knots will usually be between 0.07 knots and 0.18 knots.
For a GW52, worn on the head, it is between 0.04 and 0.065 Knots.
Over 500m, the GW60 dopper error is in the order of 0.05-0.09 Knots. For the GW52 it was between 0.025 and 0.04 knots.
As an aside. it is clear from this example how much better the GW52 is when worn on the head.
For the 10Hz ublox M8 based gps I have tested (worn on my head), the error figures are commonly as good, or better than, the GW52, and at 18Hz, they are better again.
Error for individual points at Higher Hz rates is higher, but this error cancels out to a lower overall error over more points. The method we use may be slightly optimistic, in that it might not fully take into account all the the sources of error, all the time, but it was tested against the Luderitz fixed gates in 2013 by Manfred Fuchs, using data from myself and others, with Ublox M6 10Hz and GT31's and came up very close. By that I mean the differences were mostly within the error margins calculated for the GPS and the video timing. Later model GPS chips have been proven to be significantly better (lower error), so I would be very surprised if the results were not much closer if we repeated the tests.
The point I am making is that the current approved devices are, for all our intents and purposes, as good as the WSSRC 500m record video timing.
It is my understanding that current RTK systems are generally accurate in the order of 3-5cm in dynamic use. Fixed survey can get within a cm. Think about how difficult it would be, even for a surveyor, to measure the 500m course video transit markers at Luderitz and keep them within a cm or two! I think this is why they are reported to be set around half to one meter over 500m, although some of that will be to take into account the video timing error range as well.
Going back to the WSSRC GPS error allowance. If you add 5cm to each end of the 500m course (500.1m), you will have to go approximately 0.01 Knots faster to get your 50 knots = 50.01 knots (I worked it out on 25m/s. which is 48.5961 knots) . So just for the GPS alone they allow for around 0.01 knots error.
If a fixed video timing course of 500m is actually set at 501m, you would have to go 0.1 knots faster to get your 50 knots = 50.1Knots, and this is not taking into account video timing error range. It appears to me that our current best Doppler devices are capable of at least this order of accuracy.
Which makes me wonder: Even if we have an RTK device capable of 3-5cm positional accuracy, are we any better off than with current Doppler? (I know it would make the Alpha more accurate because of the current positional error range in the proximity circle)
Caviet: I am absolutely not competent in Maths, so please check my calculations for dumb errors! 
Select to expand quotesailquik said..
The point I am making is that the current approved devices are, for all our intents and purposes, as good as the WSSRC 500m record video timing.
I did not check your calculations, but I bet you are right.
The biggest issue I've seen with both u-blox and GW-60 data is that the errors are not random anymore when the signal is poor (SDoP near 1). Here's an example from a driving test (which avoids issues like hand movements) from 2 GW-60s lying side-by-side:
Speed was around 65 knots, differences in the region shown are 0.5-1 knot, the region is about 3 seconds long. Note that one of the two watches consistently shows higher speeds over a couple of seconds (~10 points). There are multiple regions in the tracks where the SDoP values went up, and one of the watches would consistently be higher than the other for a few seconds. This would be extremely unlikely for purely random error - basically, the error is not random. In such regions, the average error should be used for estimates, not the much lower estimates that GPSResults gives. Measuring this region at a higher rate would not help: you'd get the same averages, but an even lower error estimate (which would be even more wrong).
What's the relevance? If you go from 5 Hz to 18 Hz, the reported accuracy is likely to up by a factor of almost 2. The actual accuracy, however, may not have changed, because the math used is based on assumptions that are not met by the data. What definitely goes up by a factor of about 4, however, is the file size, and the wait time when the software calculates results. Switching categories in GPSResults when looking at a longer 5 Hz session already requires lots of patience (the same is true for GPSAR whenever it has to calculate alpha500s).
I think you are probably correct in about the error not being 'random' in the situation where the SDOP is quite high. Thankfully, that is pretty rare when on the water sailing in normal conditions, during the runs that count, with the GPS worn well for good sky view. Of course you are always going to get poor data when submerging the GPS during crashes and water starts etc, but those bits should never count in anything.
Tom Chalko made the statement several times that the Doopler error gets better when speeds increase. He tried to explain to me why that is a couple of times, but I did not really understand it fully. Others who did understand his reasoning agreed with him so I just accepted it.
Tests done with multiple side by side Higher Hz devices do support the least squares averaging though, up to at least the Nautical mile distance. After that, the differences between devices sometimes fall outside the error range reported (for instance - 1 hr).
I agree that file size seems to be an issue for processing some large high Hz files. And the UBX files can be much larger than the SBP files, although I find the processing time pretty much the same. It is one of the reasons I generally only use 10Hz from the ublox M8 though, rather than 18Hz.
Hmmm....
I think I see what you mean though. Here is my max speeds from that session:
What is notable here though, is that the Max speeds from both devices are still a long way within the worst reported error range, and well inside the best reported error in the GW52 in most cases. .
I strongly suspect the higher error values in the GW60 watch were the runs I did with underhand front grip on the other tack. I can probably check that when I get the energy.
Its a pity I have not got 10Hz ubx for this session.
Looks like getting the dongle to work with a Raspberry Pi will be straightforward enough .. check boardsurfr.blogspot.com/2018/03/the-pi-logger.html
Select to expand quotesailquik said..
Or you could skip the dongle plus Rasberry Pi and use a M8 module with a larger, better antenna.
Yes, I could, and I'd get more points on the Ultimate Geek competition. But such prototypes have been in existence for a decade now, and they are of absolutely no value to anyone who does not like to put electronics stuff together. Oh, and you have to do some non-trivial programming, which has so far stymied even the Fangman, whowasgeeky enough to develop his own fins.
I am trying tofindan alternative to the GW-60 that others could use without having to solder different electronics parts together, but there is positively no chance that I will do any kind of manufacturing and selling. I'm trying to come up with an "open source" GPS where just aboutanyone who can install apps on a phone and plug in cables can get one. The Android phone - dongle version was the first try, but it's pretty pointless since OTG phones are so expensive in Australia and Europe. The Raspberry Pi, on the other hand, is available for cheap everywhere, and the Zero W had the small form factor, Bluetooth, WiFi, and other connection options (USB mass storage).Select to expand quotesailquik said..
Send the output via BT to GPS-Logit in your Android phone.
The current version of GPS-Logit on Google Play does not support bluetooth - or if it does, there's absolutely no documentation about how to do this. I understand that he has made a version available to you and Roo that will support it (and/or given you the instructions), but he has not bothered to respond to me when I expressed interest in this version in a email. So that's actuallynotan option.
Re-posting the same pictures of prototypes won't help anyone who does not want to spend $250+ on a GW-60 because the bands break; screen repairs cost as much as a new watch; and Locosys has a "peculiar" attitude towards warranties. Trying to get someone else to make a GPS we can use, or to piggy-pack onto a device developed for other purposes, has also failed - several times already. Maybe a plug-and-play, open-source approach will work better.
BT Module:
I think that Boardsurfr's approach of using easily obtainable, off-the-shelf, and plug-together componentry is a very good approach. Not only does it make it the assembly process easier, but allows for simple hardware experimentation, configuration and upgrades. Going for distance and want your logger to last all day on a small battery? Unplug the screen etc.
I tried to make mine using an Arduino board and Ublox8 and found the soldering and assembly no big problem. The issue I had, was my code efficiency. It worked but I could not get the data processing done without bottlenecks. The quantum leap in processing power of the Pi Zero should remove that problem, and I am also sure that Boardsurfr's code is waaaay better than mine as well. I am excited about this project and I really hope that Boardsurfr's efforts come to fruition. ( plus I will have something to do with all the bits n pieces of a GPS lying on my desk :-)
Select to expand quoteboardsurfr said..
Yes, I could, and I'd get more points on the Ultimate Geek competition. But such prototypes have been in existence for a decade now, and they are of absolutely no value to anyone who does not like to put electronics stuff together. Oh, and you have to do some non-trivial programming, which has so far stymied even the Fangman, whowasgeeky enough to develop his own fins.
Well, excuse me! 
Can't see much difference to the geekiness of trying to build something with a Raspberry PI.
My understanding if Fangys project was a full on GPS that actually records data itself internally, not a BT dongle, which I am sure he could do much more easily. There was no programming required for these dongles.
And no, the standard GPS-Logit does not do BT. If there was enough demand for it, I am sure Manfred would make it available in the same way as the current vesion on Google Play.
Select to expand quotesailquik said..
There was no programming required for these dongles.
If someone sends you code that does the setup of the USB transmitter and then reads the data, then you don't have to program. Someone else has to, though. You still have to solder.
If the person who has developed the code does not release it to the public, and does not send it when asked, then yes, you will have to program to use the dongles. Saying "I'll release if there was enough demand for it" creates a bit of a chicken-and-egg problem. Charging a price for the software that is relative high for typical prices on the platform reduces demand.
Steps to build and use a Bluetooth dongle:
1. Figure out somehow which parts are needed.
2. Solder things together.
3. Put everything in a waterproof box or bag.
4. Ask Manfred Fuchs for a version on non-released software. If he does not answer, write your own software to configure the GPS and bluetooth transmitter, and log the data.
For most speed surfers I know, step 2 would be too much to ask, even more so step 4. In countries like the US, where most windsurfers have iPhones that cost many hundred dollars and will not be taken on the water, add a step to buy an Android phone, and get it set up.
Now assume someone figures out how to build a GPS Logger that's at least as accurate as the GW-60 using a Raspberry Pi, and publishes any software needed as open source, with instructions. Then, the steps would be:
1. Order parts from a list.
2. Connect cables.
3. Download and install software.
4. Put everything in a waterproof box or bag.
That's quite similar to what was needed to get a GW-52 to work. Except for the waterproof bag, it's pretty similar to what's needed with a GW-60, if you want to update the firmware or use the utility program. It certainly won't be for everyone, since you'll still need a waterproof bag and won't get a display (at least initially), but it may be an attractive alternative for some - especially given a cost that's 3-4-fold lower than the GW-60.
As the technical guy recruiter on our GPSTC team, I have had to help the majority of our team members with the setup of their GPS units, from GT-31s to GW-60s; sometimes, that included ordering devices for them. With a Raspberry Pi logger, the entire setup would take about 5 minutes by just cloning SD cards, so that's perfectly doable. Soldering stuff together is a different story.
Why so stroppy Peter
There is no programming or coding required for BT dongle - whatsoever!
Even I eventually figured out how to use U-centre to set up the GPS. Instructions easily found. You did it too for your USB dongle!
There are exactly three parts which need assembling which is no different from your idea and they have been listed here explicitly yet again.
Yes, there is some soldering - Many have a friend who can do that - I asked one nicely and he helped me.
The otter box is also available everywhere cheap for the waterproof container. Or you can get creative and find/make a smaller one.
Even you bought an Android phone in the USA for less than $100. We got them for $15-20, although I have not seen any that cheap just lately.
OK. You have your knickers in a knot because Manfred won't answer you. I wonder what you said to him?
There are alternative ways to record the BT output using a Phone.
Hey, I really do like what you are trying to do Peter. Just pointing out another way for a 'GPS alternative' that already exists, has been tested, and works.
I wish you all the best with your project. If you can get it going, and I really hope you can, I will be very interested in doing it myself. All this because we can't get a reliable, low cost OTG phone. If we could, or can in the future, I will be one of the first to try that also.
That said, the commercial GPS are still a lot more convenient and are actually low cost and simple to use compared to almost every other piece of essential equipment we use for our sport.
But DIY is always cool and interesting.
I currently use a phone (Alcatel Pixi) and it's GPS for logging and viewing sailing data. I was going to build up a U-Blox to Bluetooth interface like sailquik is talking about here. I made a diagram so I could visualize what parts were needed (I have not built it up so it could be wrong!) see below:
I did not end up making one as it seemed results couldn't be posted to GPS-TC as a home made device isn't approved (I could be wrong on this), so I started saving for a GW-60. I'm now nervous about the reliability of the GW-60 and are watching this thread with interest as to an alternative.
Can someone please confirm that U-BLOX M8N data is not currently supported for GPS-TC? If it is not supported, then I assume this is because there has been no 'mainstream' product available to test and approve?
Select to expand quotesrtgumbee said..
I currently use a phone (Alcatel Pixi) and it's GPS for logging and viewing sailing data. I was going to build up a U-Blox to Bluetooth interface like sailquik is talking about here. I made a diagram so I could visualize what parts were needed (I have not built it up so it could be wrong!) see below:
I did not end up making one as it seemed results couldn't be posted to GPS-TC as a home made device isn't approved (I could be wrong on this), so I started saving for a GW-60. I'm now nervous about the reliability of the GW-60 and are watching this thread with interest as to an alternative.
Can someone please confirm that U-BLOX M8N data is not currently supported for GPS-TC? If it is not supported, then I assume this is because there has been no 'mainstream' product available to test and approve?
The answer to you last paragraph is in the 5th post on this page. Basically you got it. No one has asked for it yet.
We didn't use a seperate voltage regulator, but it may have already been in the salvaged usb power bank we used as a battery.
The Ublox GPS is configured with the free Ublox tool: U-Centre, to output the required .ubx sentences, rather than the default NMEA.
The BT version of GPS-Logit is not yet commercially available. But there may be another way to record the data to an Android phone and Roo recorded the data to a Palm computer many, many years ago.
Andrew, thanks for the clarification. It's easy to misunderstand where someone is coming from in these posts, my bad . Hopefully, we'll get to sail together a bit next year, and have a few beers, that helps communication.
I found several web pages with instructions for a bluetooth GPS, for example at www.thingiverse.com/thing:698168
That does indeed look pretty easy. The biggest attraction is the size and power consumption of the thing. My Pi Zero right now needs about 0.1-0.15 A. The BT GPS should need less than half of that, so it should work better with a smaller battery. From what I read about the serial-to-bluetooth thingy, connecting it to the phone should be easy. Getting the data from Bluetooth should be a pretty straightforward modification of the app I wrote for the dongle, so I may look into that, too, if I can find my soldering iron.
I like going the easiest way, and it might actually be easier to get the Bluetooth communication going with the chip + BT-serial combo, since that requires figuring out only the receiving part. After that, I can add the sending part from the Pi Zero. Once those things work, we can ask Matthias if he can add the bluetooth functions to Windsport Tracker.
For the vast majority of windsurfers, convenience will remain the top priority, and buying a GW-60 is hard to beat on that. But having choices is always nice, and complete monopolies like the one Locosys has now rarely motivate companies to be nice to customers.
It's also fun to play around with the Pies. Things are so easy compared to early Linux days! So many things to try - maybe this: after a session, disconnect the GPS, and connect a USB stick. The Pi automatically copies the new data file to the USB stick, and then shuts down. Or maybe just use the Bluedot Android app to shut the Pi down, after transferring the new log file over bluetooth. So many things to try!
I look forward to meeting you Peter.
I like to idea of using the Rasperry to construct a recording logger. That makes a lot of sense to me. I am guessing it could also have a very large battery life and very large memory? For many things one does not need a display screen, and there are other ways to get that.
Obviously easier and simpler to do with that GPS ublox7 dongle, but is it much more complicated to connect it to a ublox 8 or 9 module with a larger antenna? It would all have to go inside a waterproof case anyhow.
Just looked again and those M8n GPS module with patch antenna are now down to Aus$15 to 16.
For those interested in using a Raspberry Pi Zero, I found this nice battery solution that allows you to use all sorts of power options and provides some shutdown protection as well.
juiceboxzero.com/
It is a kickstarter project and I don't know if they have actually got any to market yet - I have contacted them but not heard back yet. I will post if/when I know more.
Thank you Andrew for clearing up my question
I also think the Pi zero W is a great idea. The power consumption is high in comparison to an embedded solution, but the versatility and potential ease of use more than make up for it. The red battery in the Cell phone + Bluetooth interface Andrew posted above, looks to be a 18650 cell and these commonly come in 3400mAh capacity. I could see a Pi fitting in that same container with the same battery and even if it were drawing 0.2A, it would last for 17hours.
I just checked the hardware schematic and the Pi takes an micro SD card so you have many GBs to play with.
The Pi has its own voltage regulator (3.3V and 1.8V) so it can be powered directly from a Lithium ion cell of 3V to 4.2V. The Pi's header pins allows access to the 3.3V output and RX and TX data so hardware wise the Ublox M8N could be soldered onto these pins. I assume the software setup would be easier or the same as using the USB GPS dongle?
The end product could like the logger described here: rtkexplorer.com/pi-zero-based-gps-data-logger/ Looks ideal!
I follow this thread with interest as the GT 31s get older and the watch is a piece of crap. I figure that when I run out of GT 31 I'll retire from GPSTC as the watch is just useless for me.
So the question is ... is there an off the shelf product that I can purchase that will log speeds , record and have a battery and storage good for 24+ hrs. A screen isn't necessary. I can do a bit of soldering but forget anything fancy or programming.
Select to expand quotekato said..
So the question is ... is there an off the shelf product that I can purchase that will log speeds , record and have a battery and storage good for 24+ hrs. A screen isn't necessary. I can do a bit of soldering but forget anything fancy or programming.
Gyro.
There was also a Dual xgps500 high precision Logger and BT dongle that was shown as 'coming soon' in 2016. It was to be based on the ublox M7p GPS. It promised to be great for us but I can't find any mention of it now so I guess the $ case for it didn't add up and they didn't go ahead with it. It would have been 3-4 hundred dollars though.
I have not seen any word from Flysight for a while, but their GPS logger also uses the Ublox7 GPS and can probably be configured to output ubx data with doppler error. Last I looked they were about Can$250.
But for those who want the best, the Gyro from the Netherlands is the go. It uses the ublox M8 GPS, has a screen with all the GPS sailing categorys (genie) feedback, is slightly smaller than a GT-31, but is custom made for windsurfing. Custom order only as far as I know, but their website still says they are not yet accepting orders.
gearloose.nl
The development story here: forum.windsurfing.nl/viewtopic.php?f=62&t=13890429 (use a translator App - it is all in Dutch)
Select to expand quotesailquik said..
Obviously easier and simpler to do with that GPS ublox7 dongle, but is it much more complicated to connect it to a ublox 8 or 9 module with a larger antenna? It would all have to go inside a waterproof case anyhow.
You're talking about 2 different things: 1. using a newer ublox chip, and 2. using a larger antenna.
1. Using a ublox 8 instead of a ublox 7 requires no changes per se. The same holds when ublox 9 thingies become available. Even ublox 8 USB dongles are now available, but have to be ordered from China, which adds a few weeks of delivery time. The biggest potential advantage of the ublox 8 is that it can track Galileo sats, vs. just GPS and GLONASS in the ublox7. More satellites can increase accuracy, and Galileo may be better than GLONASS.
2. A larger antenna means a non-USB connection. The VK172 mouse has an 18x18x2 mm antenna; the ublox 8 modules often come with 25x25x2. A larger antenna should improve signal strength and thus accuracy. However, this requires some soldering, and therefore will not be "plug and play".
The big question is how much can be gained by upgrading the chip or the antenna. You have mentioned Manfred's results from L?deritz, where even a ublox 6 was as good as gated timing. The data with the ublox 7 dongle are very good if the reception is good. If the USB dongle would be mounted on top of a helmet, any improvements in speed accuracy that could be achieved with newer chips and larger antennas would probably be in the 0.02 knot range - largely academic with no practical relevance.
Accuracy problems arise when the GPS is worn on a less-than-ideal location, and the satellite signal is partly blocked. Examples are the GW-60 in an underhand grip, or an armband holding any GPS slipping so that it is under the arm, or between the arm and the body. The interesting question is how much a newer chip and/or larger antenna will help in such a situation.
The fun thing is that all this can be quantified. We have two outcomes we can look at, the SDoP values and the accuracy compared to other units in multi-GPS tests. We can correlate that to primary measurements (# of satellites, satellite distribution, and S/N ratios for each satellite), and then see how things change for different configurations (top of the head, upper arm, under arm, ...). One possible outcome is that "clear view" is much more important than anything else; another possible outcome is that a newer chip with a larger antenna works wonders and gives great data regardless of obstructions. Chances are the result will be somewhere in between; I'd like to know where exactly. I got some ublox6, 7, and 8 chips lying around.
The nice things about making your own logger and recording software are that (a) it's very easy to change recording options (for example add detailed satellite information), and (b) it's cheap, so you can make a few for tests without having to spend hundreds or thousands of dollars.
One of the things I'd like to check out are "fatter" antennas, for example an 18x18x4 mm patch antenna. Orientation of the antenna to the satellites seems to be very important. The phone antennas, which are basically small 2-dimensional sheets with almost zero thickness, do quite well when pointing up, but the signal degrades more if they point the wrong way. It could be that the thicker antennas are less sensitive that way; at least that's what the graphs in the papers about GPS antennas seem to show.
Of course, I really hope that it will be too warm and windy soon to do all these things..
