Does the Mapillary app support the use of an external GPS, either Bluetooth or through the charging port. Like http://bad-elf.com/ for instance?
Those hardware GPSes usually have a higher accuracy than the built-in GPSes in the phones, and sometimes the built-in ones use cell network triangulation before they get proper signals from the satellites.
Hi!
The support is IMHO not nativly built in, but android does have that support inside.
Mostly it is not worth the hassle, really.
Modern, good mobile phones do have good enough GPS/GLONASS/Galileo… receivers
I’ve noticed that my iPhone 5 drops the GPS signal now and then. Especially in forests and in rocky areas. This results in map trails where it looks like I’ve flown across the terrain. 
However, my iPad’s GPS receiver works much better.
@Patrick, if this is occasional then you’ll be able to fix it with the help of our upcoming editor. If systematic then it’s oc worth to look into this more.
If it’s a desktop editor, then… 
This is not a Mapillary issue.
I use a Garmin GLO and a Samsung S7. I stopped using it for a while because all the hassle to start it. But now that the leafs are on the trees, I need it again.
In the latest Android version it is not necessary any more to go in the Android developer settings to make it work.
But I recommend to wait for Galileo, unless you have too much money. I don’t like also that these device use a mini USB socket, all my other devices have an micro USB socket.
I want my next external GPS faster than 10 Hz.
GPS in modern phones will never be comparable to the external ones, simply because you cannot fit a proper GPS antenna into modern thin phones, you will never see MTK II or MTK 3333 which has -165dBm sensitivity rating and 66 channels. I have Holux RCV-3000 and it works perfectly with my phone. It connects by means of Bluetooth and you will need additional app on the phone that will decode NMEA stream from data logger to the mock GPS signal, so the phone will use that signal in all apps. I record tracks with OSMTracker for my mapping in OSM, if satellites distributed evenly in the sky and you have lock on 10-11 of them then 1.7 meters accuracy could be achieved. GPS data logger saves gps-data as well, so you will have a backup. Though I use my action camera for Mapillary mapping, I still use the Mapillary app on the phone to take pictures of the information signs in the parks, POIs when I stop to survey them.
My experience is that the Samsung GS7 has not a better reception than my GS5. Even though the GPS signal should gradualy become stronger.
What smartphone has a Galileo receiver ? I very mucht doubt it is available. In the mean time I will suppose that you don’t know what you write about.
Just one condition has to be not optimal and the accuracy becomes volatile. I often regretted not having my external GPS available.
Do I understand you right that the device and the app will replace the built-in GPS receiver signal with the external device’s, so that any app can make use of it?
Yes, you understood right, every app will use the mock GPS provider from external GPS unit, and external GPS unit is a savior, in the places that my phone will have pure satellite lock or none at all external GPS will have at least 7-8 in view, that’s because my unit has -165db sensitivity, meaning that it will lock even to the weak satellite signal. In all rough conditions that I used it in, it done well, I would get average accuracy of 2.3 m under the foliage and inside the train carriage. I bought it in the first place to increase accuracy of my tracks for OSM mapping.
Hi!
Sure, a good external GPS/galilkeo/glonass/… receiver with a good antenna, good software,… is mostly better than every mobile phone receiver. But it is always a hassle to get them, use them right, wait until they are locked down, sync them with the mobile… Also they do cost >50 €.
Over all, it is far easier and by far enough to use the mobile phone you already got, just start the app and all is fine. No need to sync files, no need to fiddle with lots of tools, hardware…
If you are addicted and dedicated enough, you can get a good receiver with good antennas, mount them on the outside of your car and sync them via bluetooth to your mobile phone and use mapillary with it.
But currently I cannot find any good gps receiver with bluetooth working out of the box and <100 €. And sorry, I do not want to fiddle with images and seperate gps tracks to combine them, if I can have the easy way. Not for a 2-5m better accuracy. Really.
echelon
Yes, you are right, mine data logger costed me 90$, it locks within 30 seconds, phones lock so quickly because they use assistance from cell towers. So everyone decide for themselves if it worth it or not, if you use it for mapping, agriculture measurements etc. then external GPS unit is a go.
Is there a way to tell if a phone or tablet has locked to cell towers or gps signals?
It uses the cell towers only at the start to determine approximate position of the device (50-100 m accuracy) and to download almanac data (contains predictions about satellites positions for nearest future) then GPS unit will lock to the satellites much faster, its called A-GPS, assisted. And as far as I know there is no way to see that, on android phones you position could be even taken from last known position in Google location services if that option enabled in your phone.
Yes,
that is was “Enable Mock GPS Provider” means.
I understand that that option is intended to debug applications providing fake GPS positions, having nothing to do with the use of A-GPS or not.
“Enable Mock GPS Provider”
I do not know about A-GPS, but this is the only way to have an external GPS receiver in Android, as far as I know what I write about. Debugging or not debugging.
Ok, since I have never used external GPS on Android I’ll take your word about it. 
Anyone know if Mapillary on iOS can bypass CoreLocation when working with an external unit (eg Bad Elf) and get raw data?
My Galaxy Note 8 seems to receive all constellations. In the GPS Test app I can see all the satellites from US, Russia, China, Japan, EU. So new phones can see all the new satellites now (2018+). This thread started in 2016! But it reports it does not use SBAS signals. That is a pity because my Garmin 78C does and there is an experimental service in my area. The coordinates returned by my phone are still not very good because the photos are too fast for averaging to take place, if that was enabled. Averaging for waypoints where you stay still for a while improves the accuracy for some purposes.
I have done a comparision with tracks from the Garmin and Galaxy and there is a significant error (+/-15 metres) using the phone. I agree that external post-processing is a hassle, the phone uses local timestamps but the Garmin uses UTC times and we have daylight saving too.
So the ideal would be to connect the Garmin to the phone and adjust on the fly. Now I understand what that funny reverse connector I found in the box was for - to connect the USB cable from the Garmin to the phone.
All I have to do is set up the Garmin to send out NMEA sentences, turn off the phone GPS, turn on developer mode and allow GPS mocking to read the external stream instead. Still working on that…