Returning 3rd Garmin Edge 500 unit, poor GPS lock in London

ydrol

I live and commute in London. I am about to return my 3rd Edge 500 because it fails to GPS lock.
I have applied all software updates, and regularly do AutoLocate reset (LAP+Start) to reinitialise the GPS tracking status.

But still I can do my entire 1hr commute and it fails to get a lock and then shuts down.
As I work from home the unit can be off for serveral days between use.

My experience is that given the price, and that the main function is that it is a GPS computer, that these things are pretty poor. However all the reviews look pretty good. Am I missing something?

[I do know how to do all of the various resets but often it doesnt seem to 'take' and just shuts down after not finding satelites]

These are not cheap unit's so a little dissapointed. I thought I was buying quality but feel like I've just fallen for marketing hype..

itboffin

How central are you?
I work in the city and have practically no Garmin GPS and when i do its way off course and gives crazy speed and altitude readings, oddly my mobile works almost perfectly apart from right in amongst the tall glass buildings where i've clocked 70 mph 8)

ydrol

I commute from SE London/Bromley to Euston. I think I'll check ebay resell prices once I'm sure the unit works OK, just not great on London perhaps? I suspect I'm wasting my time sending it back to Garmin again.

My first 'return' was an Amazon refund and re-purchase, thinking it was just a dodgy unit. The next was a Garmin warranty replace, but I'm seeing the same behaviour - failing to lock despite resets etc.

pastryboy

I sort of get this as well. My 500 works like a charm on the commute in. However, when I leave work the gps takes ages to lock on - the progress bar gets right near the end but drops back again and again.

I think it's the tall buildings (I work near Canary Wharf). It generally locks on when I get a little along the road away from the buildings.

I had a 200 before and whilst it took a while to lock on at first, it seemed to learn where it was after a few weeks and it had no trouble where the 500 does.

turbotommy

Is it that the unit never locks on to a gps signal at all or a combination of that and loosing signal once locked in?

I too own a 500 and live in London. I find that being in an open area and not moving too much, as well as turning it on in a similar spot each time, both help to find a signal faster. It can take a few mins which is a little annoying but if you're turning the unit on and immediately taking off on your ride it will definately reduce your chances of getting a signal.

Even though mobile phones call their system gps it actually works through mast triangulation rather than satellite gps so it can zero in on your location at lot faster.

I Use my phone for my daily commute into the city and my garmin when I'm going on longer rides or training and that seems to work for me. Good luck

sloppyschleckonds

My 2nd 500 has just failed, going to try a 510

timothyw

In short, the 510 is certainly worth a go as you can turn on GPS + GLONASS mode which ought give much more accurate results in challenging conditions.

GPS relies on minuscule timing differences between the arrival of signals from satellites in space - anything that confuses those signals, such as a building in the way, heavy cloud cover, interference from local radio signals etc (all of which are fairly common in London) is going to reduce accuracy and increase lock-on time.

If the GPS receiver hasn't been used for a while (or I suppose if you've done the autolocate reset on your edge 500...) then it needs to obtain a fresh copy of the 'Almanac', the part of the GPS signal that contains information on satellite position, this can take several minutes and needs a clear signal from at least one satellite. The reason that early GPS units took so long to lock on was because they started from scratch obtaining the almanac each time they were turned on - more modern units (such as the Garmin Edge's) cache the data in order to accelerate things.

Mobile phones are able to download a fresh copy of the almanac via their data connections, which is much quicker than receiving the signal from the GPS satellites - they can also get semi-accurate locks by triangulating the cell phone antennas they can see, and local wifi-hotspots (each of which have a unique thumbprint).

If you haven't used your edge 500 for a while, it's always a good idea to switch it on plenty of time before you set off, leaving it ideally outside but failing that on a windowsill with a clear view of the sky, in order that the almanac data can be received before setting off.

itboffin

I used my 705 today to route me across counties via some very twisting back country lanes, it was faultless which is a first, so much so that back in the early days I made a promise to myself never to use the routing and maps as my sole method of getting from A to B

It helps having an idea and double checking the route isnt planning on taking you down dirt ttacks

apreading

Resetting the GPS wont help as it will have to start from scratch and will take longer to get a lock. If you have had a lock and then turn it on from the same location within 24 hours or so, it seems to find where it is much quicker as it already has an idea to start from.

When finding a lock, all non internet accessible GPS devices must first get a satellite and download the identities of the other satellites, their locations and time stamp. Only then do they start looking out to see which ones they can hear and working out what the bearings are to get a fix. If you reset they have to download all that information over again. Assisted GPS (usually on a phone) uses an internet connection to get that data much quicker and usually gets a lock quicker as a result.

I dont know why you have such trouble - any time I have used mine in london it has been flawless - admittedly not often but on occasion and never had a problem. Any time I get my phone out it gets a lock pretty quickly too.

mroli

My 500 in the centre of London would often take 2-3 min to get a decent lock. Sometimes when I got moving, it would take a lot longer than that - I always thought it got confused by that....