Jul 302012

Besides still being a great home and WiFi email client, browser, movie player, camera, voice recorder and MP3 machine, I was hoping to be able to use my old HTC EVO 4G phone as an ultimate GPS voice-guided turn-by-turn car navigation system even without a data connection, but it failed during my first test drive.

I am in a process of changing phones so my EVO 4G now has no data or phone connection.  After downloading some Google map “tiles” of my areas to the phone for offline use, I  tried today to use them, but it only “kind of” works, to my disappointment.  The GPS radio showed my position and movements on the map after getting a lock, however, I couldn’t get any driving instructions, which means all the maps I downloaded are good only for viewing but not for navigating.  Furthermore, neither Google Maps nor Navigation app was able to pinpoint my home address on the map when I searched for it, although it is on one of the downloaded areas (I was trying to navigate back home just to see how it works).  Unless I’m doing something wrong, it seems that Google still needs to connect to the server to get navigation instructions, even if you have the map(s) containing the areas of your driving downloaded on your device, so I might have to get the driving instructions while connected to the internet.  That’s fine for a single trip, but if you decide to make a detour to look for gas or a dining place, you may be running into a dead end map, at least till you get to the next available Wi-Fi connection.

UPDATE: I tried that next.  Got my destination while on WiFi and Google Navigation proposed three different routes.  The first included a toll road, the second had a few train passages where I might have to wait and the third begun with an insane gas-wasting runaround, but since it is a beautiful drive and I promised myself I’ll take a scenic route whenever I can, I still chose it and decided to optimize it on my own because I know the roads very well.  When I took the shortcut in the beginning it started telling me to make a u-turn at every crossroads, so I thought it would blindly stick to the route it got while connected to the internet, however, a mile or so later towards my destination it “changed its mind” and started recalculating.  I purposely didn’t follow another turn a mile later so it recalculated again and gave me an updated route.  That’s good.  It works on a destination chosen while connected to the internet and it later recalculates and updates in real time without a data connection. What’s bad, is that I still wasn’t able to pinpoint an address on a map downloaded for offline use.   That feature would be really nice to have when in remote areas without signal or lost in the mountains when you life depends on it and your phone just can’t tell you where that lodge is.

Next experiment: I’ll try to navigate with downloaded Google Maps on my HP TouchPad with CyanogenMod 9 Android.  Even though  this tablet doesn’t have a standalone GPS radio, it should be able to pinpoint its approximate location when multiple WiFi signals are available.

  2 Responses to “Unable to Navigate Downloaded Google Maps on Android without Data Connection”

  1. Well you havn’t updated so I can only guess it didn’t go well. but yea I could tell you it wouldn’t work, for one most peoples wifi are no longer open these days. You may see 2-4 access points but you will be lucky if 1 is open, this means no location data from 3 of them. Also the nature of wifi does not allow multiple connections for triangulation, and then there is the fact that wifi location look ups are a guessing game from online services based on your isp provider and no gps data is used.

    In short, it is impossible to navigate without a gps transmitter.

    I too was hoping to use my old optmius V as an offline GPS though, sad to see I will probably need non-google software.

    • You guessed right; I couldn’t navigate with TouchPad even with maps saved because it doesn’t have a gps radio.

      However, Google does use WiFi when GPS signals are weak to triangulate and it doesn’t need open WiFi, because it only uses the names of the WiFi networks they recorded in the area, but this worked on my devices only when there’s also a data connection available. It has sort of a map of known access points and SSIDs (WiFi network names) tied to the map so when the GPS radio doesn’t see many satellites they can still triangulate based on the limited GPS info combined with the mobile tower info, combined with a more or less known WiFi mesh. This works for example when I’m driving through Chicago downtown where there’s so many high buildings that are obstructing satellite navigation.

      But you are still sort of right, because lacking a GPS receiver and cellular data the TouchPad is dead in the water and will show location only if connected to a WiFi network.
      When I used to have a WiFi hotspot configured on my phone I was able to connect and use Google Maps and Navigation on the TouchPad and it worked great. I guess it was getting the GPS position from the phone. Without a data connection and a GPS radio it’s a dud even with downloaded map of the area and WiFi enabled but not connected. I guess my expectations were too high.

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