WatchUSeek Watch Forums banner
1 - 9 of 9 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter · #1 ·
The watch seems to take a long time to acquire a signal compared to other GPS devices I own. To experiment, outside with a clear view of the sky, not moving, and the X10M showing 5 bars, if I turn off the GPS then within a few seconds turn it back on, it can take up to 90 seconds to reacquire.

Other devices I have refer to cold versus warm start-ups - cold being moving more than 500 miles and/or not having the unit on for a while. With my other devices, including the Garmin Forerunner 405, the reacquisition is within a few seconds.

Is seems the X10M considers everything a cold start and does not use any previous data to get a fix.

The situation is made worse when walking. It is my experience that moving increases acquisition times in general, but in this case the X10M took approx 8 minutes to get a fix before showing 5 bars.

I suspect my unit is not defective because it eventually shows 5 bars, but this is puzzling with a newer generation GPS chip.
 

·
Registered
Joined
·
14,018 Posts
LOL... you have GOT to be kidding me? I would KILL for 90 seconds. LOL Tell you what, you borrow my X9 and see how you like them apples! LOL

Try 7-9 minutes... clear sky... not moving... LOL.

90 Seconds is a nice improvement!
 

·
Registered
Joined
·
1,574 Posts
It is because the X10 does not have an internal atomic clock like traditional GPS devices do. In order to keep the size down, they have removed the internal atomic clock, and instead take longer to get three or four agreeing signals from the GPS satellites to calculate a correct time. Then it can determine the correct position based on the inforamtion.
 

·
Premium Member
Joined
·
7,747 Posts
It is because the X10 does not have an internal atomic clock like traditional GPS devices do.
You're going to have to explain this one ...

I know of no consumer GPS devices which have an "internal atomic clock."

What exactly do you mean? :-s
 

·
Registered
Joined
·
1,800 Posts
You're going to have to explain this one ...

I know of no consumer GPS devices which have an "internal atomic clock."

What exactly do you mean? :-s
Yeah, I didn't ever read about my Garmin GPS60CSx having this feature. When I turn it on though I get a lock on in a few seconds if I have already locked it previously that day in the same location. I even get a lock indoors...:-!
 

·
Registered
Joined
·
1,574 Posts
Well the wayit was explained to me....

GPS devices basically use a clock. on each standard GPS device there is an atomic clock which receives a signal broadcast from the national institute of standards that constantly updates time. A similar feature is on some of the Casio Pathfinder watches...

Well satellites orbiting the earth are sent this information as well. The GPS signal that you actually recieve is a time code and location code from the satellite. By comparing the time signals on each of the three satellites and comparing them to the atomic clock built into the receiver, you can calculate the length of time required for each signal to go form the satellite to the receiver, and thus the distance. A fouth satellite is required to calcualte the altitude and corrects for timing discrepancies.

All GPS receivers have an onboard atomic clock (except the Suuntos). Because the receiver for an atomic clock is relatively large, (as the Casios with this feature are not exactly diminutive), this takes up a lot of space. Suunto has opted to eliminate this part in favor of a software solution that captures multiple signals and uses that to calculate the exact time. The result is longer lock times, but with less parts.

This is why it takes SO much longer time to get a good position lock when you are using your X10 while moving to get your first lock...
 

·
Premium Member
Joined
·
7,747 Posts
Well the wayit was explained to me....

GPS devices basically use a clock. on each standard GPS device there is an atomic clock which receives a signal broadcast from the national institute of standards that constantly updates time. A similar feature is on some of the Casio Pathfinder watches...

Well satellites orbiting the earth are sent this information as well. The GPS signal that you actually recieve is a time code and location code from the satellite. By comparing the time signals on each of the three satellites and comparing them to the atomic clock built into the receiver, you can calculate the length of time required for each signal to go form the satellite to the receiver, and thus the distance. A fouth satellite is required to calcualte the altitude and corrects for timing discrepancies.

All GPS receivers have an onboard atomic clock (except the Suuntos). Because the receiver for an atomic clock is relatively large, (as the Casios with this feature are not exactly diminutive), this takes up a lot of space. Suunto has opted to eliminate this part in favor of a software solution that captures multiple signals and uses that to calculate the exact time. The result is longer lock times, but with less parts.

This is why it takes SO much longer time to get a good position lock when you are using your X10 while moving to get your first lock...
Well ... whoever explained it that way was ... wrong. :-x

See a good explanation HERE about how the signals from 4 or more satellites are used to correct the internal clock (can be a simple quartz watch movement, NOT an "Atomic Clock") of the GPS receiver to yield a correct position.

There are no "Atomic Clocks" in any consumer GPS receiver.

Any delay in "warm start" and "cold start" acquisition time is most probably due to the software algorithms used to assume a position before adequate satellite signals are acquired.

HTH

ETA:

All GPS receivers have an onboard atomic clock (except the Suuntos). Because the receiver for an atomic clock is relatively large, (as the Casios with this feature are not exactly diminutive), this takes up a lot of space.
Do you have an example of a Casio GPS receiver with an "Atomic Clock" which is "Not exactly diminutive?"

.
 

·
Registered
Joined
·
1,574 Posts
I misspoke in calling them "atomic clocks" they are in fact Radio clocks

And the Pathfinder 1500 is an example of this type of device..

Yes- an atomic clock has Cesium oscillating between magnetic fields and yada yada yada...
 

·
Registered
Joined
·
49 Posts
Discussion Starter · #9 ·
I am not 100% sure this is complete, but I think the issue of a cold versus warm start is a software algorithmic issue, as mentioned above.

When powered off, the other GPS units remember either the location and / or the specific satellites in view. Then when powered on, either using the list of satellites that were previously viewed, or determining a best guess of which satellites based on current time and previously stored location, a group of satellites is determined.

If most of those satellites are in view, acquisition is quick. Otherwise, the unit must try different combinations of satellites to see which are in view, and that takes the longer time.

If this is an accurate explanation, then it is hard to understand why it is not implemented by Suunto.

But, again, I may be missing something....
 
1 - 9 of 9 Posts
Top