I had a Garmin unit a few years ago, but sold it because it constantly lost contact with the satellites when under tree cover. Are the new units, specifically the 820, any better? Is there anyone out there riding one under tree covered roads? If so, can you offer a comment an the unit's ability to maintain contact?

Thanks...

Occasionally any GPS receiver can lose satellites, depending where they are in the sky, what the weather is like (cloud cover and rain don't help), tree cover, canyons natural or urban, etc. It's happened a few times with my 800 and once with my Fenix 3 (not using GLONASS).

Newer units use GLONASS (Russian GPS) as well as US, so that improves reception. I also think newer units in general have better reliability. My 810, which was introduced 3 or 4 years ago, gets great reception in wooded areas. You can also add a $40 speed sensor which tracks distance and speed better then GPS, so if you momentarily lose reception, the unit keep tracking.

How many years back, which Garmin device?

I have an Edge 800 and it works fairly well but as mentioned above, all GPS devices are susceptible to loss of signal. Some devices are better than others, my Edge 1000 is better than my 800 in holding a signal not that my 800 is bad.

I also have a Forerunner 405 that seems to lose signal if I look at it wrong. That's why I asked which device and how many years back. Things have improved IMO.

It's a feature, not a bug. GPS was originally designed and deployed for ships and airplanes, no buildings, trees, or mountains to get between satellites and the receivers.


Some of the newer antenna designs in the last 5 years or so help with sensitivity, but they can still lose lock when the sky view is obstructed.

What puzzles me is that my phone (an iPhone 6s) never loses signal. Why? I'm tempted to give one of the new units a try, since the use of GLONASS might be s difference maker.

Do you really know for sure that your phone never loses the signal? Maybe it does, has clever software to deal with it, and doesn't tell you?

I know that when I run Google Now on my phone, it can be very convenient, but it can give me weird results too. I'll park my car at home, walk into the house, and it'll tell me the trip home will take 30 minutes with current traffic conditions.

iPhone will fall back to using the cellular network for location if GPS signal is lost.


-Tim-

It might lose the GPS signal frequntly and you never know. It's not like Apple lets you know.

Which begs the question, what happens to a tracking app, RWGPS, MapMyRide, Strava, etc.. when you have no data ?, does the phone app keep tracking ?

You'd almost have to try tracking your route next summer under the leaves and see if it tracks smooth. You could turn the phone to airplane mode to eliminate cell tracking (I think a lot of tourists do this for battery saving). If you map the track and it looks like you jumped half a mile down the mountain and then back up, it lost track.

Maybe the phone does lose signal, but I don't see the huge "straight line" gaps in my strava routes, and the mileages are consistent with my bike computer. My old Garmin would lost signal for miles, and when i uploaded the route it would draw a straight line between contact points. So if the phone is losing signal, it seems to be compensating somehow. If I can't rely on a GPS unit to work as well, maybe I shouldn't bother.

If you are riding in area's with cell data service, then likely the app can still track using cell tower locating.

Thus my question as to anyone know how/if these units track with no cell data ?, relying on GPS alone ?.

Not tracking well or at all somewhat makes the case for a dedicated GPS receiver, as it does when trying to use Google maps in a car when you have no cell data service.

If GPS signal isn't available tracking based on cell towers would be extremely coarse and next to useless. Cellular phones can use the network to speed up GPS acquisition but they still need a GPS receiver within the phone. Most cell phones can receive GPS without any cellular connections.

Yes, but the question really is, can the assorted apps - RWGPS, MMR, Strava still function and track if cell data goes away ?.

Strava can, except their newer 'beacon' service wouldn't work. Not sure about the others but I don't see why not.

Damn, I'm still not sure if a new GPS is worth it. I'll wait, I guess.

Buy one from, for example, REI next spring. Try it out, and if it loses track, take it back.