AccuTracking

I'm tracking a unit at 5 minute intervals with a Boost i415 phone . I'd like to know why I'll get a good black GPS location fix, but then after that, I'll get a lot of red Cell Tower Locations, like for hours at a time, when the unit I'm tracking hasn't moved at all for hours ? Then, I'll get a good black fix again, and the unit appears to have moved a few yards, but then again, I'll get hours of Cell Tower locations after that. This causes the Travel Report to be incorrect, and I often can't tell exactly how long the unit was at particular location if it really does move and the next black GPS fix is miles away. BTW, at first I thougth this problem was caused by a low battery and poor signal strength, but it has been happening with a full battery. If I can get a black GPS fix and the unit doesn't move for hours, shouldn't all of the entries in the tracking history be black and not have a bunch of red cell tower locations mixed in ?

Please help explain this.

Thank you.

The red cell tower locations has nothing to do with phone moving or not. It only occurs when the phone cannot get a GPS fix due to poor sky views. And cell tower locations are not considered as real GPS positions by geofence alerts and travel reports, as explained here in the knowledgebase.

The drifting you see in the black GPS positions is a different issue. It's the normal fluctuation of the GPS signal and shouldn't be greater than a few hundred feet.

I understand that cell tower locations are not real GPS locations and that when it can't get a good GPS fix it will find the nearest tower. My question was that if the unit isn't moving and I already got a good black GPS location, then why don't I continue to get the same relative location in black while the unit remains in the same place ? Why do I keep getting like 1 - 2 hours of the same cell tower location before I get another GPS fix in black, even when signal strength and battery power are good ? This doesn't make sense to me.

Thanks for bearing with me on this topic.

That's because the GPS acquisition may succeed or fail at different time, even at the same spot, due to the gps quality. For example, when I take the phone into my house and can see the acquisition fail 90% of the time at the same spot. So this is really GPS reception related. You might not be using indoors but your reception could be blocked if installed in cars.

Your phone may be standing perfectly still, but dont forget that the 27 or so GPS satellites are constantly moving around the Earth thus the GPS geometry is constantly changing. Your phone may be able to see 5 satellites now but then in 5 minutes it may only be able to see two satellites because they have all moved several thousand miles during that time.