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Author Topic: Problems with receiving GPS signals  (Read 36086 times)

Hubert

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Problems with receiving GPS signals
« on: May 05, 2010, 02:59:54 am »

Hi Geoffrey,

yesterday I wanted to perform some kind of a simple interval training (3 Min. fast / 3 Min. slow).

I did everthing like I do always: I drove with my car to one of my training tracks. When I left my car,
I switched the watch on. Then I changed my shoes (from normal shoes to running shoes) and went
about 200m from parking lot to training track. I did this many times before and the time, needed from
switching the watch on to starting my training was always enough to get the satellite fixed.
Yesterday is wasn't !  >:(

Yesterday there was one difference: I wanted to use the time during satellite finding to change my auto
lap setting. So I changed it from distance based auto lap to a 3Min. time based auto lap.

When I started my training, the watch told me, that GPS is weak and asked if I want to start my training
anyway. From previous trainings I assumed, that it could only take a minute to get GPS signals.
So I started my training.

To make the story short: There was no GPS signals for about 20 Min. !  :(

But this wasn't the only problem !

Of course I was waiting for the 3Min. auto lap alert. When I first looked at my watch it was already 3:45
and I thought, I might haven't heard the beep. Same at 6:10. Next I watched the display from 8:50 to 9:10.
There was no alert !  :(

So I forgot the watch more or less and continued my training.

Then after about 20 Min., I suddenly noticed, that the total time had changed from before 23:xx to 01:xx  ??? :o
The GPS signal was there and reseted the timer !  :o Oh no !  >:(

The good thing was, that from now on, the auto lap worked as expected.  :)

The bad thing was, that also after finishing my training, the first part of my training (without GPS) was
completely gone. Disappeared. No data all.  >:(

As a summary, there a the following items:
* Why did it take about 20 Min. to get GPS signals ?
* Why does timer based auto lap not work without GPS ?
* Why is training resetted when GPS signals comes ?  (This is really the worst part  :'( )
   I think we had a similar discussion for GH-625 and I thought it was solved...

There is one more item:
During the first 20 minutes, the watch asked me if GPS should be resetted (Y/N).
I do not understand the meaning of this question ! Can you explain, what happens exactly, when I answer
Yes or No ?

Regards, Hubert
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TWG_TECH8

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Re: Problems with receiving GPS signals
« Reply #1 on: May 08, 2010, 03:36:54 am »

Hi Hubert,

It is appreciated that you provided so detail information! Let's cool down to make thinking: :D

Here is my answer to your questions:

Quote
I did this many times before and the time, needed from
switching the watch on to starting my training was always enough to get the satellite fixed
Did the GPS be off? Or the whether was worse than before?


Quote
There is one more item:
During the first 20 minutes, the watch asked me if GPS should be resetted (Y/N).
I do not understand the meaning of this question ! Can you explain, what happens exactly, when I answer
Yes or No ?

Quote
To make the story short: There was no GPS signals for about 20 Min. !
It is recommended facing to sky to get 3D fix and then go for training. Because GPS antenna needs to aquire completed ephemeris for 42s, if we change atenna direction, the signal is easy to get lost.

Quote
There is one more item:
During the first 20 minutes, the watch asked me if GPS should be resetted (Y/N).
I do not understand the meaning of this question ! Can you explain, what happens exactly, when I answer
Yes or No ?
After power on device and if didn't get fix for 3min. Watch will ask you "RESET GPS?" to peform cold start in order to get faster fix.

For sure, the timer will be resetd till get 3D fix in order to get accurate training performacne likes avg speed, total training time...

About the alert time, I will do more check.


Sincerely,

Geoffrey

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Hubert

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Re: Problems with receiving GPS signals
« Reply #2 on: May 08, 2010, 05:13:39 am »

Hi Geoffrey,

thank you for answering and of course I like to share our ideas:

Following my answers:

Quote
I did this many times before and the time, needed from
switching the watch on to starting my training was always enough to get the satellite fixed
Did the GPS be off? Or the whether was worse than before?
Of course GPS was activated. And signals were received after about 20min. without any further
settings. It came up automatically. That means: GPS was on all the time for sure.
Weather was good ! Almost clear sky. Only a few clouds. Shouldn't be a problem.

Quote
Quote
To make the story short: There was no GPS signals for about 20 Min. !
It is recommended facing to sky to get 3D fix and then go for training. Because GPS antenna needs to aquire completed ephemeris for 42s, if we change atenna direction, the signal is easy to get lost.
Okay - I didn't do that (and I have never done this before...).

For sure, the timer will be resetd till get 3D fix in order to get accurate training performacne likes avg speed, total training time...
"For sure ? " No - I really do not like this. And I think, I'm not the only one.
When timer is resetted, maybe you get a better value for avg speed - however a lot of other things
are completely wrong: like total distance, total time, Max/Avg HR, calories and more.

As a compromise, I could imagine, to allow the timer to restart, but to save the first part of the data.

About the alert time, I will do more check.
Okay - that's fine.

Regards, Hubert
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abdominizer

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Re: Problems with receiving GPS signals
« Reply #3 on: May 08, 2010, 01:05:52 pm »

For sure, the timer will be resetd till get 3D fix in order to get accurate training performacne likes avg speed, total training time...
"For sure ? " No - I really do not like this. And I think, I'm not the only one.
When timer is resetted, maybe you get a better value for avg speed - however a lot of other things
are completely wrong: like total distance, total time, Max/Avg HR, calories and more.

As a compromise, I could imagine, to allow the timer to restart, but to save the first part of the data.

I would rather have timer running and some values incorrect! Especially if I don't get 3D fix before the start of a race. In a race a timer reset would be very bad, at least for me, with timer running you could always do your math in your head to se how you are doing, a timer reset will complicate a lot!

Regards,
Jonas
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Hubert

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Re: Problems with receiving GPS signals
« Reply #4 on: May 09, 2010, 05:27:03 am »

I would rather have timer running and some values incorrect!
... a timer reset will complicate a lot!
Exactly !

Regards, Hubert
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TWG_TECH8

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Re: Problems with receiving GPS signals
« Reply #5 on: May 09, 2010, 10:43:53 am »

Hi Hubert,

Quote
"For sure ? " No - I really do not like this. And I think, I'm not the only one.
When timer is resetted, maybe you get a better value for avg speed - however a lot of other things
are completely wrong: like total distance, total time, Max/Avg HR, calories and more.

As a compromise, I could imagine, to allow the timer to restart, but to save the first part of the data.

Our scenario is:
1. 3D fix? -->Yes Go (2a)
                   No Go (2b)
(2a) Start timer to training and record data Go 3.
(2b) Start timer to training, get 3D fix and then reset timer and then record data
3. Stop timer
4. Saving data

The logic is same as GH-625 and should be no problem.

Geoffrey
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Roger C

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Re: Problems with receiving GPS signals
« Reply #6 on: May 09, 2010, 12:43:07 pm »

Hi all!

Well we bought a GPS watch and in the manual it says, before start get 3dfix, because its very hard for the satellites to get a fix when we start to run.

But to say that reset of the timer when we get a 3D fix is correct is also totaly wrong, of course should the timer never be reset until i choose to do so, but if that happends in a race...then my gh-625 have done its final race. And it never reset when i lost the 3D fix when i already have started my race, with GPS fix, so that problem at start should not be a problem for the watch.

A "simple" fix to this should be that if we dont have time to wait for a 3D gps fix, it should automaticly start in indoor training mode, with no GPS enable, this is a much easier way to use indoor mode.

So no gps fix = indoor mode

Have a nice workweek all ! :)

/Roger "problemsolver"

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Longjog @ GS-Sport-Servicecenter

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Re: Problems with receiving GPS signals
« Reply #7 on: May 09, 2010, 12:43:45 pm »

Hi,

my GH 505 runned its first marathon with me today.
Disappointment is big. Not because of me but because of the GH 505. It would have been better to take the GH 625 with me.
What has happened?
Before start I started the watch to get 3D fix. It was raining and cloudy, but it did get 3D Fix after a while. Then I started but I have to notice the GPS accuracy was not as good as I accustomed. The first 1k auto lap was 35 m to early and this did go on every kilometer. So pace and AVG Pace were "to fast" also. At the 16k sign I had 18,4 k on my GH 505. At 35 k on the watch GPS-signal was lost  >:(.
I do not think this was a problem with signals of the satelites but with the receiving of them with the watch.

The days before I noticed that GH 505s Auto-Lap function did beep mostly earlier than GH 625, (I didnīt wear them the same time, but I know at which points of my standard-track my GH 625 did beep).
Maybe this is a problem of the firmware 1005061?
When I download the track with Training Gym Pro I can see the track often isnīt straight like the street or way I did run, but it goes left and right (looks if I was drunken 8)).
Do the other testers have also such a problem with accuracy of GPS?
Geoffrey, please help!

Regards

Longjog
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zingo

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Re: Problems with receiving GPS signals
« Reply #8 on: May 09, 2010, 01:00:22 pm »

I also do not like the "and then reset timer" part of 2b

(2b) Start timer to training, get 3D fix and then reset timer and then record data

The timer should be the single most important thing in a trainging watch that is it's reason to exist, GPS/HR and the other stuff are the secondary addons. I'd like the other values to be wrong and if possible calculated from the point where the GPS fix was made as this was the best one can do. Maybe it can be shown that this has happend by some grapically indication like bolding the uncertant values or put some symbol in the statusbar or change the GPS status icon to something other like reversing it.
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Hubert

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Re: Problems with receiving GPS signals
« Reply #9 on: May 09, 2010, 02:54:12 pm »

Hi Hubert,

Quote
"For sure ? " No - I really do not like this. And I think, I'm not the only one.
When timer is resetted, maybe you get a better value for avg speed - however a lot of other things
are completely wrong: like total distance, total time, Max/Avg HR, calories and more.

As a compromise, I could imagine, to allow the timer to restart, but to save the first part of the data.

Our scenario is:
1. 3D fix? -->Yes Go (2a)
                   No Go (2b)
(2a) Start timer to training and record data Go 3.
(2b) Start timer to training, get 3D fix and then reset timer and then record data
3. Stop timer
4. Saving data

The logic is same as GH-625 and should be no problem.

Geoffrey
Hi Geoffrey,

the fact, that GH-625 has the same logic doesn't make things better... Far from it !

But you are right. I remember, that we had a similar discussion for GH-625.
And I myself had the same problem with my GH-625 one time in vacation when I first started
my GH-625 at a complete new position. Even after 10 min. there was no GPS fix and I
decided to start my training anyway. And after another 10min. the timer was resetted  :'(

The current procedure you decribed is the worse I can imagine (sorry to say that...).
You could do almost everything, but don't reset the timer !

Let's think about a solution:

* When there is no GPS at start, there is a question, if you want to start anyway.
   That's fine. And users who have time to wait, may answer No and wait longer for a GPS fix.
* But users answering "Yes" (start anyway) want to start their training - or even more
   important: their competition !  Their decision means: YES, start normal training (including
   every possible function !) and GPS data is not needed.
* They want to have the timer. They want to have HRM. Maybe calories (I don't need them).
   They want to have everything. And they accepted, that GPS will not be available.
* I personally would expect, when GPS signals become better, from that moment on,
   all GPS related information will appear automatically - including some error caused by the missing
   start part.

How could that be done ?

* Isn't it possible to start the watch in a mode similar to indoor mode ? Indoor mode also provides
   all functions besides GPS.
* So, maybe the question at the beginning could be changed to: "No GPS. Start in indoor more ? Y/N ?
* And then, same as before: Answer "No" means: Wait for GPS.
   Answer "Yes" means: Start in indoor mode. With all functions included (besides GPS).
* And could it not be possible to try to get the GPS fix during this mode and switch GPS
   functions on as soon there is a GPS fix ?

This would meet my personal expectations of a smart watch.
And I would like to know, how other users think about it.

Fortunately this situation seems to happen very seldom, and maybe not all users have made
this experience. But if it happens, we should have a good solution.
Maybe we should share this discussion (somehow) also with GH-625/615 users, because
they all are involved.

Regards, Hubert
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GH-505 M, Firmware: F-GGH-2C-1007161 (Beta)
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abdominizer

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Re: Problems with receiving GPS signals
« Reply #10 on: May 09, 2010, 02:55:43 pm »

Our scenario is:
1. 3D fix? -->Yes Go (2a)
                   No Go (2b)
(2a) Start timer to training and record data Go 3.
(2b) Start timer to training, get 3D fix and then reset timer and then record data
3. Stop timer
4. Saving data

The logic is same as GH-625 and should be no problem.

Geoffrey

Geoffrey,
I Know this logic is the same as in GH-625, but there has been discussion about this before and I think we concluded it would be better to keep timer running. Resetting the timer will cause more problems as said before!

Sincerely,
Jonas
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abdominizer

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Re: Problems with receiving GPS signals
« Reply #11 on: May 10, 2010, 01:44:18 am »

You could do almost everything, but don't reset the timer !

Let's think about a solution:

* When there is no GPS at start, there is a question, if you want to start anyway.
   That's fine. And users who have time to wait, may answer No and wait longer for a GPS fix.
* But users answering "Yes" (start anyway) want to start their training - or even more
   important: their competition !  Their decision means: YES, start normal training (including
   every possible function !) and GPS data is not needed.
* They want to have the timer. They want to have HRM. Maybe calories (I don't need them).
   They want to have everything. And they accepted, that GPS will not be available.
* I personally would expect, when GPS signals become better, from that moment on,
   all GPS related information will appear automatically - including some error caused by the missing
   start part.

How could that be done ?

* Isn't it possible to start the watch in a mode similar to indoor mode ? Indoor mode also provides
   all functions besides GPS.
* So, maybe the question at the beginning could be changed to: "No GPS. Start in indoor more ? Y/N ?
* And then, same as before: Answer "No" means: Wait for GPS.
   Answer "Yes" means: Start in indoor mode. With all functions included (besides GPS).
* And could it not be possible to try to get the GPS fix during this mode and switch GPS
   functions on as soon there is a GPS fix ?

This would meet my personal expectations of a smart watch.
And I would like to know, how other users think about it.

Fortunately this situation seems to happen very seldom, and maybe not all users have made
this experience. But if it happens, we should have a good solution.
Maybe we should share this discussion (somehow) also with GH-625/615 users, because
they all are involved.

Regards, Hubert

I agree! Good suggestion Hubert!

Regards,
Jonas
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Longjog @ GS-Sport-Servicecenter

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Re: Problems with receiving GPS signals
« Reply #12 on: May 10, 2010, 06:56:27 am »

I agree! Good suggestion Hubert!

Regards,
Jonas
I fully agree also but I also ask myself why does the watch need so much time to get 3D-fix?
Okay, when the GPS is resetted (coldstart) it will need some minutes to acquire the signals. But if it is a warmstart normaly the 3D-fix should come in less than one minute.
If you have a competition you know all this and you can switch on your watch early enough to get 3D-fix.
At my comeptition yesterday I did have to wait several minutes to get the 3D-fix, but I did get it - and I did lost it after 35 km. But why? Other GPS-watches did receive GPS-signals all the time, but my brandnew GH 505 not. Maybe only 4 satellites were received and this is the reason for the inacuracy (for example: at the 16k sign GH-505 says 18,4k). Every kilometer was to short. First only some 10 meters but suddenly my pace jumped from 4:30 to 3:50 without really getting faster. Reason was the distance which was measured to long. (750 real meters, or near by this, were measured as 1k).

I did have the problem of lost GPS-fix when I used GH505 the very first time and yesterday, when I was 45 km away from the town the last time I have had a 3D-fix.
Hubert, you have written you did have had problems getting 3Dfix when you have been in holiday, far away from home.
Do you think itīs possible this can be a reason for an insufficient GPS-fix?

Regards

Longjog

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abdominizer

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Re: Problems with receiving GPS signals
« Reply #13 on: May 10, 2010, 08:49:33 am »

I agree! Good suggestion Hubert!

Regards,
Jonas
I fully agree also but I also ask myself why does the watch need so much time to get 3D-fix?
Okay, when the GPS is resetted (coldstart) it will need some minutes to acquire the signals. But if it is a warmstart normaly the 3D-fix should come in less than one minute.
If you have a competition you know all this and you can switch on your watch early enough to get 3D-fix.
At my comeptition yesterday I did have to wait several minutes to get the 3D-fix, but I did get it - and I did lost it after 35 km. But why? Other GPS-watches did receive GPS-signals all the time, but my brandnew GH 505 not. Maybe only 4 satellites were received and this is the reason for the inacuracy (for example: at the 16k sign GH-505 says 18,4k). Every kilometer was to short. First only some 10 meters but suddenly my pace jumped from 4:30 to 3:50 without really getting faster. Reason was the distance which was measured to long. (750 real meters, or near by this, were measured as 1k).

I did have the problem of lost GPS-fix when I used GH505 the very first time and yesterday, when I was 45 km away from the town the last time I have had a 3D-fix.
Hubert, you have written you did have had problems getting 3Dfix when you have been in holiday, far away from home.
Do you think itīs possible this can be a reason for an insufficient GPS-fix?

Regards

Longjog

Hello all,
I have not had any problems with inaccurate distances or lost 3D-fix with my GH-505 but I have noticed that it takes more time to get a 3D-fix than my old GH-625 does. When starting my run from home and the last run I did also ended at home, the GH-505 always take a couple of minutes to get a fix, my GH-625 will get a fix in under one minute. In a cold start away from home at a X-country race in the middle of the forrest the GH-505 took over 15 minutes to get a fix, but to be fair I was walking in a heavy pineforrest at that time and me moving combined with poor GPS coverage might have been the reason for the long fix time.

Regards,
Jonas
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Test getting 3D-Fix
« Reply #14 on: May 10, 2010, 11:20:52 am »

Hello,

I made a test with my GH615 and GH505

Switch on
GH615 0:58 to 3D-fix, with 6 satelites
GH505 1:40 to 3D-fix, with 4 satelites, 5 after a while

then switch of, turn on again:

GH615 0:01 (at once) to 3D-fix
GH505 0:40 to 3D-fix

Why???

Regards

Longjog
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