Is it me only or most common? Recently my logs comes with up to 30 minutes holes.GPS GW 60
30 Nov
26 November
apparently another sailor , same place, same time experienced even worse reading
What do cause the problem? Are we preparing for WWIII or UFO just landed near by recently?
Luckily we are not yet at the stage of self sailing autonomously windsurfing boards. Could crash for sure or make a good dip towards New Zealand with such navigation.
third sailor at same place
then Brisbane 60 km away affected too
But suprasingly Lake Cootharaba ( 300km ) wasn't yet invaded by Aliens !? or just single hit at 3pm exactly
Yep, story becomes more and more fascinating. The most probable explanation is that Earht was hit by wormhole ( Time shifting device/phenomenon) that cause Y2K problem appear suddenly after 20 years past.
www.abc.net.au/news/2019-04-10/weather-balloons-grounded-in-gps-clock-rollover-glitch/10984806
poor sat coverage on the Eastern states. If you change the filters to say 4 sats instead of the default 5. I predict those holes will get smaller.
The dater is probably there, but the filters are preventing the from displaying. Although looking at the green line, (the sat numbers), that bad period of yours has periods with no reception at all.
And the bottom display is still showing mainly 5 sats. Looks more like he was having a rest. You'll notice he has a thick black line at the bottom. you don't.
The thing with the watch with it's smaller antenna and wrist mount it's often not in the best position for good reception. Not using the underhand grip will improve things, but probably not enough in your case.
It can also be instructive to turn on SDoP when looking at this stuff.
This is particularly and issue with the GW-60 becasue of the way it is worn on the wrist and is often in underhand grip (all watch type GPS will probably have this issue).
Here are the satellite visibility/availability charts for 28/29th Nov at Wellington Point, Qld.
Note that with the elevation mask set at an optimistic 10 degrees, there is still a maximum of 5 or 6 sats that should be available for the early afternoon. But some of those could be very weak (low in the sky)
.
But notice also that if we raise the elevation mask to 20 degrees (above the horizon), it gets a LOT more problematical for a much greater period of time. Any of the yellow period is likely to be an issue:
The best advice I can give, if you know there is low satellite availability, is to try to avoid underhand grip, or to wear your GW-60 on a different part of you body so that the antenna has a better sky view.
Generally speaking, we dont see this issue with the GT-31 as it has a larger antenna, and is usually worn on the upper arm where it usually has a better sky view. The same applies to the GW-52 because it too is usually worn the same way.
This is also a big reason why the Motion GPS is a big step forward. It is Multi-GNSS. That means it can use the satellites from two (or even 3) seperate systems. Ie, GPS plus another (usually Glonass or Gallileo). AND, it is worn on the uper arm. So a situation with an inadequate number of satellites for a very good solution (fix) is extremly unlikely to arise.
Select to expand quotesailquik said..
This is particularly and issue with the GW-60 becasue of the way it is worn on the wrist and is often in underhand grip (all watch type GPS will probably have this issue).
Here are the satellite visibility/availability charts for 28/29th Nov at Wellington Point, Qld.
Note that with the elevation mask set at an optimistic 10 degrees, there is still a maximum of 5 or 6 sats that should be available for the early afternoon. But some of those could be very weak (low in the sky)
.
But notice also that if we raise the elevation mask to 20 degrees (above the horizon), it gets a LOT more problematical for a much greater period of time. Any of the yellow period is likely to be an issue:
The best advice I can give, if you know there is low satellite availability, is to try to avoid underhand grip, or to wear your GW-60 on a different part of you body so that the antenna has a better sky view.
Generally speaking, we dont see this issue with the GT-31 as it has a larger antenna, and is usually worn on the upper arm where it usually has a better sky view. The same applies to the GW-52 because it too is usually worn the same way.
This is also a big reason why the Motion GPS is a big step forward. It is Multi-GNSS. That means it can use the satellites from two (or even 3) seperate systems. Ie, GPS plus another (usually Glonass or Gallileo). AND, it is worn on the uper arm. So a situation with an inadequate number of satellites for a very good solution (fix) is extremly unlikely to arise.
Motion has been a 8 month wait for people since ordering. Still not an option readily available.
Select to expand quoteCocky2 said..sailquik said..
This is particularly and issue with the GW-60 becasue of the way it is worn on the wrist and is often in underhand grip (all watch type GPS will probably have this issue).
Here are the satellite visibility/availability charts for 28/29th Nov at Wellington Point, Qld.
Note that with the elevation mask set at an optimistic 10 degrees, there is still a maximum of 5 or 6 sats that should be available for the early afternoon. But some of those could be very weak (low in the sky)
.
But notice also that if we raise the elevation mask to 20 degrees (above the horizon), it gets a LOT more problematical for a much greater period of time. Any of the yellow period is likely to be an issue:
The best advice I can give, if you know there is low satellite availability, is to try to avoid underhand grip, or to wear your GW-60 on a different part of you body so that the antenna has a better sky view.
Generally speaking, we dont see this issue with the GT-31 as it has a larger antenna, and is usually worn on the upper arm where it usually has a better sky view. The same applies to the GW-52 because it too is usually worn the same way.
This is also a big reason why the Motion GPS is a big step forward. It is Multi-GNSS. That means it can use the satellites from two (or even 3) seperate systems. Ie, GPS plus another (usually Glonass or Gallileo). AND, it is worn on the uper arm. So a situation with an inadequate number of satellites for a very good solution (fix) is extremly unlikely to arise.
Motion has been a 8 month wait for people since ordering. Still not an option readily available.
The fact is that the Motion is still currently the best out there. Good things come to those with patience. 
If you can't wait, the GW-60 is still the best of the rest keeping in mind what is written above.
Nothing will ever be perfect for all people.
Here is an example from Budgie today. I was using my GW60 and Motion. The GW60 missed my best run of the day (40.1kts) but fortunately the Motion saved the day.
Interesting that the GW60 even with missing sats, had a very similar looking graph.
So was that an underhand grip on the down wind run? Looks like you lost reception as you went downwind, and got it back as the run finished
Select to expand quotedecrepit said..
Interesting that the GW60 even with missing sats, had a very similar looking graph.
So was that an underhand grip on the down wind run? Looks like you lost reception as you went downwind, and got it back as the run finished
No the GW60 was on my back (left) wrist which would have been facing upwards.
Be careful with your time zones Daffy, those graph you posted are for GMT. We are 11 hours ahead so right in that nasty yellow patch. My run was at 3:44 pm NSW time
Select to expand quotetbwonder said..
Be careful with your time zones Daffy, those graph you posted are for GMT. We are 11 hours ahead so right in that nasty yellow patch. My run was at 3:44 pm NSW time
Ahhhhh!!! Stuffed up again! 
Sat availability table corrected. But it does look like there should have been OK availability at the time of your run. And if the GPS was overgip, something else must be at play on this track. It's a bit of a mystery........
I have had the same issue a couple of times recently. On the most recent occasion, I spoke with other sailors as it happened, three GW60's and two GT-31's lost signal at the same time(just after 4pm NSW), regardless of orientation. It lasted about 20 minutes then all devices worked fine again for the rest of the days sailing.
Hmmm..... I wonder if some bad Foriegn State actor is meddling with the GPS system, as part of a nefarious plot to undermine the GPS-TC? 
Today I put a GT 31 on the roof at home for 10 hours from midday until 10pm (NSW Daylight saving time, GMT +11 hours). I then exported the satellite data from Real speed into Excel and then superimposed this data (The blue line) on to the Satellite prediction chart. The funny thing is to make it align I had to shift it 2 hours. So it looks like a predicted time of 2PM equates to an actual time of 4PM.
This is really confusing. Daffy can you figure this out?
It beats me!
on the face of it, it looks like an error in the time zone offset calculation, but that would be very surprising.
I have however, forwarded your results to Navcom support to see what they say about it. 
Seen dropouts on my GW-60 in the past but it's become worse lately it's not the devices
I attempted to repeat Andrew's experiment here in Vic.
I was curious to see if there was any significant difference between 3 different GPS only GPS's.
GW-60
GW-52
Ublox M8 custom GPS sending data via Bletooth to GPS-Logit on Android Phone.
(The latter I had to run at 18Hz so it defaults to just using the GPS GNSS)
The test went from 2.26pm to 6.26pm Australian Eastern Daylight saving time.
My computer graphics skills are no where near as good as Andrew's, so here are the results in separate pictures:
Prediction from NAVCOM: (yellow is 6 sats) @10degree mask
2.30pm - 6.30pm
GW-60:
GW-52
UBLOX GPS:
Some observation about the results:
As Andrew observed, the pattern seems to lag a bit behind the predicted table. In this case by about 1 hr.(The graphs are for the exact same time span, but I could not quite get the scale the same)
I was a little surprised that the smallest antenna (GW-60) 'saw' almost identical sats as the next largest (GW-52) and the largest (Ublox)
Even more surprising because I set the GW-60 with the screen and antenna facing the sky, but when I came to turn them off, it was upside down on the steel roof of my trailer with the screen and antenna facing down! Perhaps the steel sheeting was acting as a ground plane?- I am going to have to repeat the experiment on a different surface?
Only the Gw-52 dropped briefly to just 5 satellites.
The Ublox did seem to get one more satellite than the others for some of the time, so that may be the effect of the larger antenna.
An interesting side issue is that I have sat signal strength indication for the UBLOX GPs, but not the the Locosys 5Hz ones as they don't save it, one small advantage of using the NAV-SAT sentence in the UBLOX for research. The older GT31 SBN file give the satellite position, but not the signal strength, so I can't do any direct comparisons for that.
The Android phone was down the 1% battery power when I turned it off, but I was surprised that it did last the 4 hrs logging at 18Hz.
GPS-SpeedReader would not open the 18Hz file! I had not even thought of that before,
It did give a partial report though.
Good old RealSpeed was the only one which actually graphed the satellites in a useful way, and was also able to export the data in CSV format. It is still a very useful bit of software, even if it has fallen well behind on some other ways.
It happened again at Yamba last Tuesday. There were four of us on the water on multiple device types and we all experienced the same dropouts at the same time. It always seems to coincide with the best winds.
Below is a sample from my GW-60.
This is a really good argument for using multi GNNSs, it's a pity locosys don't do it.
Select to expand quotedecrepit said..
This is a really good argument for using multi GNNSs, it's a pity locosys don't do it.
Would also be an argument to produce your prototypes in a small series as a backup, at least until the Motion is available without a backlog. Even if it drops a point every now and then at 5 Hz, that's a lot better than loosing most points for half an hour. Might keep you busy until your back is better 
(as long as you watch your posture when putting things together).
The low sat count for the GPS system is not an anomaly, it is becoming the norm. The latest generation of birds being launched are being repositioned to benefit American assets. Jamming and s****ing are becoming the norm in certain areas so assets are being repositioned to boost SNR as part of the preventative measures. With the worldwide coverage from the various systems there's no need for the American GPS to cover every area of the globe. If you want full coverage using all the systems spend $20 for the latest receivers.
Select to expand quoteRoo said..
The low sat count for the GPS system is not an anomaly, it is becoming the norm. The latest generation of birds being launched are being repositioned to benefit American assets. Jamming and s****ing are becoming the norm in certain areas so assets are being repositioned to boost SNR as part of the preventative measures. With the worldwide coverage from the various systems there's no need for the American GPS to cover every area of the globe. If you want full coverage using all the systems spend $20 for the latest receivers.
That does not help with Using GW60, GW52 or GT31.
GarminDoppler is working fine on GPS at the same when over devices fail even without using Glonass.
Canmore is also not having the data drop out.
Select to expand quoteCocky2 said..
GarminDoppler is working fine on GPS at the same when over devices fail even without using Glonass.
Canmore is also not having the data drop out.
Evidence??
Select to expand quoteRoo said..
If you want full coverage using all the systems spend $20 for the latest receivers.
Please explain.
Select to expand quotesailquik said..Cocky2 said..
GarminDoppler is working fine on GPS at the same when over devices fail even without using Glonass.
Canmore is also not having the data drop out.
Evidence??
If you want files I can do that for you no worries. All checked in GPS results.
as Garmin and Canmore do not count satellites then they still give a result.
GPS results only lets you filter down to 3 satellites so will not show data if less.
You can also check Trackpoint data on the file and it is picking up data during the dead periods.
Select to expand quoteCocky2 said..sailquik said..Cocky2 said..
GarminDoppler is working fine on GPS at the same when over devices fail even without using Glonass.
Canmore is also not having the data drop out.
Evidence??
If you want files I can do that for you no worries. All checked in GPS results.
as Garmin and Canmore do not count satellites then they still give a result.
GPS results only lets you filter down to 3 satellites so will not show data if less.
You can also check Trackpoint data on the file and it is picking up data during the dead periods.
Thanks. What I would like to see is if other devices are getting more satellites, not just giving a results with less than the specified minimum of 5. PM'd you.
Select to expand quoteRoo said..
The low sat count for the GPS system is not an anomaly, it is becoming the norm. The latest generation of birds being launched are being repositioned to benefit American assets. Jamming and s****ing are becoming the norm in certain areas so assets are being repositioned to boost SNR as part of the preventative measures. With the worldwide coverage from the various systems there's no need for the American GPS to cover every area of the globe. If you want full coverage using all the systems spend $20 for the latest receivers.
What phone app is this Roo?.
And where is the sat data come from?
Is it from a multi GNSS phone, or from an accessory BT reciever?
And what part of it can be had for $20?
