So right now I just have default "GPS" enabled for my runs. I have noticed that when I go outside and click the Run (Start), the GPS takes a while to lock in (it is red and takes a good 20 secs to go green to say GPS is enabled). Is this normal? There are tall buildings by me but nothing crazy. I know I can enable GPS + GLONASS, and is that what most users do? It says it drains the battery faster than GPS, but is that only when I am using it during my runs? Or if I enable GPS + GLONASS, and never run, will my battery drain quicker if only GPS was enabled? Thanks.
The GPS + GLOSNAS will only effect you battery life while you are using an app (i.e. running). The question is how accurate is your GPS - when you look at your activity in GC is your line mostly on the road or is it all over the place? If it is all over the place, then I would try to turn on GPS+GLOSNAS and see if that helps.
As far as taking twenty to acquire a GPS lock, IMHO that is the high end of normal for an unban environment. I live in New York and I would say that it take between 10 and 30 seconds for me to get GPS. All in all the FR645 is much faster then my old FR225 at getting a GPS signal.
MrJakey For me in UK Glonass seems to have no impact on GPS accuracy or time to acquire satellites either on my 920xt or on the 935 (which is probably more similar to your 645). The time to get satellites sounds high but I can't imagine Glonass would speed it up more likely to slow it. Do you connect to Wifi often as I believe that speeds up satellite acquisition for your usual locations (I think it uploads satellite positions to the watch but I'm sure someone else on here will give a better explanation). As for battery drain I find negligible difference between glonass or not and as emr215 it only drains during an activity. What's your GPS track like when you do get a lock on the satellites?
If you're watch is regularly connected to your phone then the EPO file, which allows the watch to predict where satellites will be therefore speeding up acquisition, should be kept up to date automatically. You can check this by long pressing the Up key then selecting Settings>About and then scrolling to the end. If the file is up to date it will say EPO Current.
GPS+GLONASS will have a higher battery drain rate than GPS alone but the difference is nominal, maybe an additional 1% per hour. I've never seen a real benefit from it in my residential or trail running routes. Some people see an improve on trails, wooded paths, and in cities so it can vary.
Thanks all for the comments. I live in Brooklyn, and usually start my runs near a bridge and a tall building, so that is why it probably takes a while. So does everyone wait until it turns green from red before actually starting the run (ie the timer). When I look at my GPS the lines are straight and not all over the place, so I know it is tracking it correctly.
Yes, it does say EPO Current. What do you mean do I connect to Wifi often - I have a saved Wifi network (my home) but I never actively connect to it - is there a benefit to doing that? I only connected Wifi when I wanted to update the software.
I should note this is the 2nd 645 I have because I returned the other (it froze up) and both have taken this 15-20 secs to connect to GPS at the same start of my runs.
In general it's a best to wait until the circle goes green and you get the GPS Ready message. Not only because it's easier for the watch to finish acquiring the satellites when you're stationary, but with this watch in particular, because it's been suggested that the auto-calibration for the altimeter takes 30 seconds after getting a lock.
Thanks. So I should always be stationary when trying to lock in GPS? Sometimes I have been clicking Start - Run and then started to walk to the location where I actually start my run, getting a head start on the time it takes to lock in GPS. But I assume it is best to go to my start of run location, then try to lock in and stay still?
So if I am on the main screen, and click "Start", it takes me to the Run screen with the runner icon. At the top it says GPS in red. So I should stay stationary and wait for that GPS to turn green, and THEN click Start two more times to actually start the run timer?
What do you mean by the 3d fix / 2d fix? Sorry for all the questions! Much appreciated.
Start the run app. Stand still until GPS is green. Go to your starting point, and when ready, press the start button.
By 2d and 3d, that's 2 dimensional and 3 dimensional. 2d is x and y (think lat/lon), and 3d adds "z" (elevation) 3d is used to calibrate the altimeter.
Thanks Jim - you said you "even disable the start button until there is a 3d fix". How do you do that?
Also when you say start the run app, you mean click start once so it says Run, then click start again to show the timer - and wait until GPS turns green? Does it make a difference if you do it that way or click Start once and let GPS turn green on the "Run" screen?
