Garmin 500 time to lock

[SoreTween]

In the morning out in the burbs it takes 2-3 minutes to get a lock.  This is more than enough time for me to extract bike from shed and usually leaves me with a small wait at the gate before setting off - a minor irritation.
In the evening in central Woking among some tall buildings it takes flipping ages.  My bike is stored in a dungeon so there's no point powering on before getting outside.  I move to where I can see a reasonable volume of sky and wait up to 5 minutes.  If I get bored and move off it takes even longer to get the lock, so much so I finished my commute once last month with 17 minutes and zero feet travelled recorded (no wheel sensor on the new bike yet).

It did get washed once.  No, not caught out in the rain washed, in a kidney pocket on a 30deg cycle washed.  Functionally that cost one horizontal row of pixels near the top of the display.

Is that a reasonable wait or have I knackered it?

[rr]

seems slow, I turn mine on as I put my shoes on, exit the house, leave it on the bin with a partial view of the sky while I get the bike out and don the magic hat, mount it and I am good to go.
leaving work, I turn it on as I leave the building and have a lock by the time I've waked 50m and unlocked the bike.

[Samuel D]

Digital electronics rarely fail in a way that makes them work but work slower than normal. I suppose it’s conceivable if the analogue side of things (antenna, etc.) has been compromised in some way.

There are many factors affecting the time to first fix, but your times sound reasonable depending on terrain. My Edge 800 was perhaps a fraction quicker when used daily, but I still had to wait after packing my keys, putting on my helmet and gloves, etc.

As you’ve noticed, riding off before it has a solid fix often means the dumb thing never gets a fix.

The latest GLONASS-equipped models may be slightly quicker, though not necessarily because they have GLONASS.

None of the Garmins I’ve tried have been anywhere near as quick as my iPhone, which gets an accurate fix in urban canyons in 10 seconds flat.

[Kim]

Digital electronics rarely fail in a way that makes them work but work slower than normal. I suppose it’s conceivable if the analogue side of things (antenna, etc.) has been compromised in some way.

This might be apparent as fewer / weaker bars on the satellite display, but hard to tell without a known-good to compare it to.

None of the Garmins I’ve tried have been anywhere near as quick as my iPhone, which gets an accurate fix in urban canyons in 10 seconds flat.

They wouldn't be.  iPhones (and similar) cheat by using the network to speed up the fix: https://en.wikipedia.org/wiki/Assisted_GPS


(I don't think the GLONASS makes the fix any faster, but does seem to improve accuracy in urban canyons.)

[frankly frankie]

Cynical moi suspects that GLONASS doesn't do anything, on those models, except provide some eye-candy on the satellite page.

[SoreTween]

Thanks folks.  Prompted by thoughts here I've done a few tests. 
- Switch phone to airplane mode & reboot.
- Switch on location services and ask for a fix, it can't use assisted mode - only GPS when in airplane mode.
- Compare to Garmin at the same location.
- Repeat in 3 more locations around town.

Conclusion: The Garmin is a slower but only 5-10 seconds or so which is entirely fair given it's age vs the phone.  I've found one location to go to that is markedly quicker to get a lock in than the others.

[frankly frankie]

If you switch off and on again within 30 minutes then that is a 'hot start' and the device should get a fix within a few seconds.  In this condition most GPSs are limited more by the time it takes them to boot the software and load any maps.

Your 500 sounds faulty to me (but obviously not terminally faulty).

[Ningishzidda]

Agree with Frankie.
After only 30 mins switched off, the unit should pick up the same satellites cus the satellites take nearly half a day to orbit.
Switching on after five hours off, a new set of satellites will need to be detected, cus the previous satellites have gone below the horizon.

[Phil W]

Cynical moi suspects that GLONASS doesn't do anything, on those models, except provide some eye-candy on the satellite page.

500 doesn't do Glonass

[Phil W]

If you can turn on GPS and put with a clear view of sky before you fetch bike out. As others have said there's a whole load if data it needs to download once it's found its first satellite. So a cold start after several hours will always take a while. Built up area restricts the sky it can scan for those satellites.