garmin losing the signal? (Read 1411 times)

Garmin Forerunner 305 newbie here. I've been having 2 problems:

1.  Losing signal?  On a couple of runs I've been on using the Forerunner, all of a sudden in the run, it stops tracking via satellite and there is a straight line on the map.  It looks like it lost satellite feed, even though it didn't give me any warning on the device.  Is something wrong with the device?

2. The Garmin Connect mileage does not match Running Ahead log.   Usually about a 1/2 mile or so.  Anyone else have these problems?

Thanks and happy holidays!

Is the area where you lose the signal open, or in the city, lots of trees, etc?

I have an old 201 which is less sensitive, but these will interfere with your signal, as well, if they're dense enough.

Does it always happen near the same place? I have a couple of areas where mine will almost always drop the signal. Not sure why, because its mostly open, but it happens about 80% of the time I'm on that stretch.

There are some settings that you can adjust, I think. Make sure its set to update as frequently as possible. I can't remember exactly, but I think its every second.  Make sure the battery is charged well. Mine seems to drop more when I'm low on charge. Mine beeps when it drops the signal. This maybe be a setting you have to change as well, if yours doesn't .

The straight line is an extrapolation from the last point before it drops to the next point it picks up. If you've run some curves or corners in that time, your distance won't be accurate. If you're running in a straight line, or close, it will be fairly close.

You're probably getting erroneous pace because the GPS is loosing signal.  I'd recommend you try a few things:

1. Turn the unit on, let it sit on something (like porch railing, hood of car, etc) with a clear view  of the sky and let it acquire GPS signal. 

2. Go to Navigation > Satellite and see what it shows for accuracy.  (should be around 20 feet or lower)

3. Try clearing the GPS cache so that it has to learn and update its satellite database.  

Outside with a clear view of the sky, and with the Forerunner sitting on a surface (hood of car, for instance) press and hold the down arrow, keep the down arrow pressed while powering on, let go after a few seconds. Then check accuracy field to see if it is lower.

4. Make sure your Forerunner has the latest device and GPS software.  The Garmin web updater software (link) will help you with this.

As a computer GEEK, I'm aware of what clearing cache will do for a PC......so I can see this helping.....BUT as a brand new Garmin owned (Santa brought me one) I have to ask...How do you clear the cache on a Garmin??

For faster startup, the Garmin caches the last satellite constellation it used (which birds were used, which were primary, which were reference, etc,etc).  At next power-up it then just tries to re-establish what it last knew. This works well.  But the GPS satellite constellation is ever changing, the Garmin has different views as its location changes and all this type of thing can lead it do try and lock into the weaker satellites.

Depending on the model, the cache clear varies.  For the Forerunner 205/305, I know it is press & hold down arrow during power up.  Any of the other device reset (hard, soft) will also clear the GPS cache.

It has happened a couple of times and it wasn't near trees.  The other thing that is happening is it is reading my pace wrong.  It told me yesterday that I ran a 5 minute mile.      I am not running near trees but near water by a lake.

 Have you ever looked closely at the route when you uploaded your workout? The map will show you were the data points are and you should be able to see if you have some bad data points. I've seen some data points get place several hundred feet behind other points. It looks like I turned around and ran a couple hundred feet over again when I never did. Something like that would definitely give you an erroneous pace since the distance covered would be much longer and the time would be the same.

I actually upload all my data to Sport Tracks first and look at the route before I upload to RA. If the route has some bad points or filleted a corner, I'll edit the points in ST to get a more accurate distance.