Select to expand quote

Roo said..
SDOP values are pretty meaningless for the the GPSTC. Nobody ever checks them and there's no mechanism in the posting system for rejecting tracks that are out of range or have errors. If you are going to use the values then you need to rebuild the system/software to take advantage of them. They may be great for record attempts but that's not what the challenge is about. I doubt even 1% of GPSTC speedsailors even know what they are. For the ones that spend hours poring over the data they are a bit of a giggle but making things simple and getting out on the water are more important to the majority of sailors.

Roo

Decrepit posted prior to your post, a good example of how SDOP helped him: www.seabreeze.com.au/forums/Windsurfing/Gps/GW52-guide/?page=3

What are you going on about?

Select to expand quote

Roo said..
SDOP values are pretty meaningless for the the GPSTC. Nobody ever checks them and there's no mechanism in the posting system for rejecting tracks that are out of range or have errors. If you are going to use the values then you need to rebuild the system/software to take advantage of them. They may be great for record attempts but that's not what the challenge is about. I doubt even 1% of GPSTC speedsailors even know what they are. For the ones that spend hours poring over the data they are a bit of a giggle but making things simple and getting out on the water are more important to the majority of sailors.

Roo

I've been helping a mate sort out his Alphas, he had a 26kt last week that his captain rejected, because the positional and doppler tracks didn't align. I have a feeling that the sdop speedgraphs are a more accurate indication of how valid an alpha PB is.
Certainly when there is a dispute over questionable results, it's nice to have all the data to make some sort of judgement.

Mathew stick your head back in mate!

What I said was there is no system in place that uses the SDOP when we post to check if the track or data is accurate. It can be done manually as Decrepit demonstrated but ideally integrating into the system so it does it automatically though KA72 /GPSResults etc before posting and cleans the tracks would be ideal. The software already has filters set for sat numbers/hdop/acceleration that I initially proposed back in 2006/07. If sdop is available why not incorporate that as well to improve the accuracy. If we aren't going to use them why have them. As I said very people know what they are or understand them.

'SDOP' values are only available from certain specialised Sirf chips that have the correct firmware. Most Sirf chips do not give it and as far as we know, no phone GPS have that output.

'SDOP' values are of vital importance to the GPS-TC as they enable us to evaluate the truth of data if there is any dispute or doubt. They also enable us to test and compare GPS units to see if they can be trusted for GPS-TC. (The vast majority of GPS data producing devices can not be trusted).

There is no fields in the NMEA or .GPX file system data for 'SDOP' (or similar) values which is why we went to the binary output of SBN/SBP for the Locosys units.

UBX binary data from Ublox chips does contain 'SDOP' data.

Moving forward, the ideal would be to have devices that produce the 'SDOP' data for everyone, and use that to help automatically filter and correct the posted speeds. Tom Chalko, Mal Wright and others did propose it's addition to the software filters when it was first introduced, but it was thought to be impractical at the time because of the legacy devices we started with, and which a large number of posters were still using, (including the GT-11), which did not include that data.
We really did get the the point where it would probably have been practical just before the end of production of the GT-31 as it was used by the vast majority of sailors. Now we have been set back until a new, universally accepted 'SDOP' 'standard GPS (or GPS's) comes along and becomes readily available at low cost.

Getting out on the water and having fun is the product of many factors.

Having confidence in the numbers you produce while having fun makes it more meaningful and more fun, especially in a team competition.

Little bit off topic (windrace ) but all valid points guys.

SDOP is nice, as Mike found out he was able to tell the GT31 gave a boost (non-real) going into gybe. As an aside on my part, looking into the chip settings the other day I saw my Locosys chip had track smoothing on and static navigation off. I had thought we were getting raw data from the Locosys chip so I was a bit surprised and turned the track smoothing off and static nav on . There were also 4 options for the chip to take in situations where signal is degraded (dead reckoning options) but not knowing which would be better I just left that alone. Anyway the track data next sail was all over the place so I put the original settings back. Fancy that, the guys at Locosys know what they are doing. Seems the data is a bit filtered. Anyway as noticed before by others in comparisons , the Navi continues a little bit beyond the curve in gybes. Mikes "speed boost" no doubt was when the GT31 realized it was heading the wrong way and had to play catch up to get back on track.
Daffy said in another post (Canmore) that this overshooting the corner would not effect the alpha speed ( no doubt thinking it was just a positional error ) but as the distance IS greater whilst the time the same it will affect (increase) the alpha speed. I'm guessing the 5Hz GW52 reacts quicker to changes in direction so gives the more reliable alpha data.

However, Roo is also correct in saying that most will have no idea what SDOP is and little interest finding out. Whilst Andrew is also right saying not all gps can give this info. The obvious answer is that analysing software should have the option for SDOP and those that are interested in records can wear GPS units that produce this data whilst the rest of us can just go sailing with what we have and be just be aware of its limitations.

Hi Arseny

Just tried your app today, very interesting.

Is there a way to start it without the countdown ? (ie simple gps mode ?)

would much prefer to see and hear my speed as soon as I hit the water.

Great work ; thanks

Select to expand quote

seanhogan said..
Hi Arseny

Just tried your app today, very interesting.

Is there a way to start it without the countdown ? (ie simple gps mode ?)

would much prefer to see and hear my speed as soon as I hit the water.

Great work ; thanks

Hi seanhogan

Thank you for trying the app. Yes, you can turn off the starting procedure countdown. Use settings -> Starting procedure configuration (uncheck the first option)

I've just uploaded the new version to Google Play (#52) and recommend to update the app as the update become available.

The new version (#52) of the app contains the following improvements :

All the values inside report and GPX track contains such big amount of decimal places as it possible. It should eliminate the problems with the calculations and give the similar with the GPSLogit result.

Added stats for best 2 points because WinRace app uses usually 3 points (1 sec delay) for the best 2 sec.

Added support of GPX 1.0. The Doppler's speed, course and altitude are included in the file. Also added and ability to log NMEA lines.

Added an accuracy filter by altitude

Decrepit and yoyo thank to you both.

Select to expand quote

OK, best doppler are at 36, 37 and 38sec, best positional are at 35, 36 and 37.
So it's as I said, WindRace is using the positional data to determine the best doppler speeds, that's probably the cause of biggest difference in logit and windrace speed results.
....

The peak of the red line is 37s and the peak of the blue line is 36s The WindRace gps speed is taken from 35, 36 and 37. The three programs I have use 36, 37 and 38 from the logit data.

Although looking at the graph more closely, I think WindRace may have picked the best three, again I have no idea what is going on here????????????????

Mike, I just realized that the updated version has the same stats calculations actually.

As I wrote an Android provides two ways for receiving GPS locations. It is possible to read data from the NMEA protocol received from GPS chipset or to read the locations data on the level of the Android platform. Android possibly corrects the locations received from NMEA using some function/algoritm.

There is an option "use NMEA 0183" in Windrace app. The option controls the source of the GPS locations. And it is selected by default. At the same time other app (GPSLogit for example) can read the locations data on the Android level. That can be the a reason of the difference in data received by different apps on the same device at the same time.

Good oh, thanks for your work arseny, I'll update my program.

Hi Arseny, I note there are still a couple of issues which need sorting (does it ever end?) with Windrace app.
First is the time stamps which are recorded on the gpx file as local time but as gpx convention is for all time stamps to be UTC it mean when you run the file/track on say , gpsResult, GPS Action replay or Realspeed then the time displayed is out by however many hours local time differs from UTC. I suppose it does not matter in Europe where they are the same. If you look at the bottom of the images you see what I mean. images .

Second there is something wrong with the Doppler speeds. This is easy to notice with my Sony Xperia which is one of the phones that have course gps location in which the smallest Doppler increment is 0.25 m/s. I tried 10-12 different speed apps but they all displayed speeds going from 0.0, 0.25, 0.5, 0.75 etc.. but your app displays something different (see images). 0.25,0.5 and 0.75 are 2.8% higher on windrace but other values are lower and some almost the same. I noticed when I looked at the data before your last updates, the gpx the Doppler speeds were being recorded as 0.8 or 0.6 etc. Now you have gone to the other extreme with 15 decimal placed (!!!) but it seems like artificial accuracy of a course measurement which was rounded up or down in the first place.



[/img

There was another interesting thing. When I downloaded #52 and ran it with gpsLogit last night the speed recorded by Logit also had this strange small variance in Doppler speed identical to Windrace. It was as if windrace had taken over the output of the chip and was feeding Logit the slightly altered data. So this may explain why your data now matches Logit. Not because it is now correct but because it is giving Logit the false (Android filtered ?) data. It was also noticeable that the min recorded speed setting on Windrace app of 1km/hr was also the minimum speed of the Logit gpx track even though normally it would show zero when I was standing still. Suggesting as noted above that Windrace was controlling gps output and what Logit would show.

Now just to confuse things further, I did the same test this morning (after adjusting some Windrace settings) and now things are back to the way they were. Logit showing 0.25m/s steps and Windrace something else. (As can seen in images above.)

Now types of files.... sbp would be great if you could get your head around the SiRF binary protocol. It is amazing how much info it packs into such a small size. Each record is only 32 bytes yet has all the info a speed sailor needs. NMEA is the other extreme..huge files. To me it is bit archaic and not surprising from the 1980s. Lots of different sentences each with bits of info we need which are often duplicated in other sentence plus stacks of stuff we don't need. The little walk I did was 13kb sbp and 407kb nmea ! The sbp is only 3% the size.
In regards to gpx files, Manfred's Logit gpx file has only all we need but is 5 times as big as his sbp. Whilst your Windrace gpx file is twice as big as Manfred's with the extra stuff like VDOP PDOP etc. which personally I don't think really need. Just the HDOP.

As for NMEA. I have other apps that allow you to pick the nmea sentences in settings. I would go with just RMC, GGA and VTG but as the nmea data of your files has just one decimal point for the speed I'm not sure I'd bother using the nmea option. I certainly would not be interested in the 10 sentences of GSV data every second which make up the bulk of the file.

Anyway, I'm puzzled by the Doppler speed error and why it altered Logit recording but it is a great little app. Perhaps the font on the lat/long etc on the screen could be sharper for us old guys :-))

Well done Arseny

(edit) Perhaps you could shrink the files a bit by reducing the decimal places. Whilst 1 on the gps speed was not enough I think 15 is a bit of over kill! And for other values such as HDOP etc most programs do fine with one decimal place and surely 3 for speed should be all we need.

Hi yoyo

Thank you for the detailed report.

UTC bug fixed (version #56 uploaded).

Your feedback shows that the big amount of the decimal places and the different Doppler values (WindRace with GPSLogit) are still the subject of the investigation for me. Seems, I need to spend some more time on it (going to do some experiments, tests with my code). I will let you know about the results and updates.

Select to expand quote

Now types of files.... sbp would be great if you could get your head around the SiRF binary protocol. It is amazing how much info it packs into such a small size. Each record is only 32 bytes yet has all the info a speed sailor needs. NMEA is the other extreme..huge files. To me it is bit archaic and not surprising from the 1980s. Lots of different sentences each with bits of info we need which are often duplicated in other sentence plus stacks of stuff we don't need. The little walk I did was 13kb sbp and 407kb nmea ! The sbp is only 3% the size.

Yes, I realized that the support of sbp format should be done in WindRace. It solves the problem of the output size. Possibly I'll be able to add sbp in January or some later.

Arseny

Select to expand quote

yoyo said..

The obvious answer is that analysing software should have the option for SDOP and those that are interested in records can wear GPS units that produce this data whilst the rest of us can just go sailing with what we have and be just be aware of its limitations.

Manfred contacted me to say his GPSResults software already has a a filter built in "maximum speed error" that uses the SDOP (when available) to reject error prone data. I think we owe Manfred a big thinks for all the great software and features he has developed over the years.

Roo

Select to expand quote

Roo said..

yoyo said..

The obvious answer is that analysing software should have the option for SDOP and those that are interested in records can wear GPS units that produce this data whilst the rest of us can just go sailing with what we have and be just be aware of its limitations.

Manfred contacted me to say his GPSResults software already has a a filter built in "maximum speed error" that uses the SDOP (when available) to reject error prone data. I think we owe Manfred a big thinks for all the great software and features he has developed over the years.

Roo

Foot in mouth perhaps ... as an Aussie would say "pull your head in" ?

Actually, as you now know Roo, the SDOP values are used in both GPS-Results and RealSpeed to filter values outside a reasonable range automatically. It was implemented in RealSpeed from the start as well as in GPS-Results. I would have to check, but I think the same is implemented in GPSAR-Pro.

The next step for the future, as I said, is the 'correction' of speeds using the SDOP values, but that will have to wait until more accurate 10hz/18hz GPS's come along where the errors in the 10 second runs will be far lower and we can deduct them automatically. That might be a year or so away...

Actually Andrew I only found out it had this feature after Manfred told me by email today. I had never seen it as it is marked "Maximum Speed Error" rather than "Maximum SDoP". The HDoP filter is marked as "Maximum HDoP". I'm sure I'm not the only one that missed it. Does KA72.com have the same filter and does it implement it when posting automatically to GPSTC?

In your case Mathew I did mean stick your head back in.

Whilst there are some minor Doppler accuracy issues with Windrace (which no doubt, Arseny will sort out in the near future) for now it does not really affect the average speeds. 1/100 knot diff or less usually.




(and yes I know my hours and alphas are crap)

G'day Arseny,

I purchased the pro version and have had a couple of issues with it.

First of all It crashed every time i hit the "start recording" button (I've sent of the reports) I believe this may have been because it was set to GPX 1.1 It starts ok with GPX1.0 ticked.

Secondly since I've loaded windrace, GPSLOGIT has stopped talking to me, with or without windrace being active.

I don't know if anyone else is having any such issues.

Realistically it could be you've made the program "Idiot proof" unfortunately I'm an......

Select to expand quote

When I downloaded #52 and ran it with gpsLogit last night the speed recorded by Logit also had this strange small variance in Doppler speed identical to Windrace. It was as if windrace had taken over the output of the chip and was feeding Logit the slightly altered data. So this may explain why your data now matches Logit....

Hi Alby, I haven't tried the voice thing yet however was going to today as last 2 days the speeds have been reliable with no loss of track recording for both Logit and WRace even when screen goes off. However it seems to me that Windrace appears to be the dominant app in that I think it controls android settings.(to stop phone going to sleep etc when screen off).

Anyway check if the settings on WindRace speech is off. It may have killed all speech on an android level rather than app level.

Select to expand quote

elmo said..
G'day Arseny,

I purchased the pro version and have had a couple of issues with it.

First of all It crashed every time i hit the "start recording" button (I've sent of the reports) I believe this may have been because it was set to GPX 1.1 It starts ok with GPX1.0 ticked.

Secondly since I've loaded windrace, GPSLOGIT has stopped talking to me, with or without windrace being active.

I don't know if anyone else is having any such issues.

Realistically it could be you've made the program "Idiot proof" unfortunately I'm an......

Hi Elmo

Thank you for purchasing pro.

The only crash report I received in Google Play for the last 30 days (4 days ago on Galaxy A5) is related to the pro app with version #51. The bug was fixed and the new app version #53 was uploaded on the next day. You can update to the latest version (#55) using GooglePlay.

WRace is playing sounds with the maximum volume even if the current Android settings are different. Please check the Android audio settings on your device. Most of the apps are using those settings.

Arseny

Hi Elmo

An update: Today I've managed to reproduce the bug with GPX 1.1. Will prepare the new version soon. Thank you for the bug description.

P.S. Unfortunately no any report about the problem received via Google Play. :(

Thanks for the followup.

That's a bugger with the report because I sent 3 of last night.

I still have the issue with the sounds from GPS Logit being killed of, which coincided with the installation of Windrace

The reason why I got Logit was for Alpha feed back.

Is there anything in your script which overrides any other volume controls?

Select to expand quote

elmo said..
Thanks for the followup.

Is there anything in your script which overrides any other volume controls?

i've checked the code. WRace asks for an audio focus from Android system (they are recommending to do in such way) . It happens after the start is pressed. The audio focus is released upon on stop.
Since the app isn't finished good (you have mentioned about the bug) then the audio focus possibly could be not released. I would suggest you to reboot the device and to check the audio settings. You can also turn off the sound and voice notifications using from WindRace's settings.

Hi Elmo

Today I also tested WindRace pro with the navigator app (running at the same time). The both apps were speaking well without problems during the session (i.e. when the audio focus was gained). Let me know if you managed to solve your problem using reboot.

Arseny

Select to expand quote

yoyo said..


Whilst there are some minor Doppler accuracy issues with Windrace (which no doubt, Arseny will sort out in the near future) for now it does not really affect the average speeds. 1/100 knot diff or less usually.

Hi yoyo

I've sorted out the accuracy issues and uploaded the new version (#58).

The update also contains fixes of GPX 1.1 bug (from Elmo) and a bug of NMEA recording (happened when stop is pressed).

I've had to do a full reset of my phone as even removing the windrace app didn't rectify the sound elimination of GPSlogit.

All sorted after the reset Sexy Sadie is now whispering in my ear again.

All the best with your program there is some potential there but as the accuracy is the same as Logit (not very, compared to better GPS devices) and doesn't have Alpha calculations whatever is creating an issue with LOGIT sound that's a big problem for me.

For everyone else, If you don't need Alpha feedback during a session, then Windrace does as advertised, the results caculations aren't as detailed as LOGIT but the Audio feedback is a valuable tool when sailing.

Good luck, I'll keep watch on the development

Select to expand quote

elmo said..
..
For everyone else, If you don't need Alpha feedback during a session, then Windrace does as advertised, the results caculations aren't as detailed as LOGIT but the Audio feedback is a valuable tool when sailing.

Good luck, I'll keep watch on the development

Hi elmo

I've just uploaded a new version. The report now includes best 5 runs statistics (the detailed results). I also added the alpha stats (250, 500).

Feedbacks are welcome and thanks for watching on the development.

Select to expand quote

yoyo said..

Now types of files.... sbp would be great if you could get your head around the SiRF binary protocol. It is amazing how much info it packs into such a small size. Each record is only 32 bytes yet has all the info a speed sailor needs. NMEA is the other extreme..huge files. To me it is bit archaic and not surprising from the 1980s. Lots of different sentences each with bits of info we need which are often duplicated in other sentence plus stacks of stuff we don't need. The little walk I did was 13kb sbp and 407kb nmea ! The sbp is only 3% the size.
In regards to gpx files, Manfred's Logit gpx file has only all we need but is 5 times as big as his sbp. Whilst your Windrace gpx file is twice as big as Manfred's with the extra stuff like VDOP PDOP etc. which personally I don't think really need. Just the HDOP.

As for NMEA. I have other apps that allow you to pick the nmea sentences in settings. I would go with just RMC, GGA and VTG but as the nmea data of your files has just one decimal point for the speed I'm not sure I'd bother using the nmea option. I certainly would not be interested in the 10 sentences of GSV data every second which make up the bulk of the file.

...

(edit) Perhaps you could shrink the files a bit by reducing the decimal places. Whilst 1 on the gps speed was not enough I think 15 is a bit of over kill! And for other values such as HDOP etc most programs do fine with one decimal place and surely 3 for speed should be all we need.

Hi yoyo

Both SiRF binary types: SBP and SBN(limited kinds of records) are supported now by the WindRace.

The significant changes were done to improve the calculations and to write the data with the appropriate precision.

I've also added the filtering of the NMEA records. NMEA log file includes only the significant sentences by default. The accordance between NMEA data (input) and GPS track (output) can be checked much now easier.

feedbacks are welcome.

Hi there

Some improvements were performed since the last post. One of them is useful for the GPS-Speedsurfing fans. Now WindRace allows you to upload your session into GP3S from the report:





Arseny