[TX21]

Hi all,
I'm having some issues with my GPS for my Revolution flight controller. The GPS in question is a uBLOX-NEO-6M. In the LibrePilot GUI that the flight controller is receiving new data but there is no fix. I know that it is meant to take longer on first boot since it is downloading a lot of data, however it has been doing this for several hours and was wondering if there could be anything else wrong with it

[hwh]

It depends on if you're outside or inside a building.  If you're outside then the GPS is probably bad, worst case it should get a fix in 15 or 20 minutes.   Inside a building that's pretty much normal.  Most GPS won't get a fix inside.

[TX21]

Yes I am inside, thanks for that. I will try moving outside/to somewhere where there is more likely to be a signal. Never realised GPS had such weak penetrating power

[hwh]

GPS was designed for the US military and not originally intended for civilian use.  The signal level was set really low, almost the same as noise.   This was done during the cold war apparently hoping the USSR wouldn't notice the signal or something like that.

[TX21]

Interesting, I've tried moving to a room with a glass ceiling but to no avail. I had a look under the system tab and it appears that the GPS is receiving time packets but no location packets. Is there a chance that autoconfig has incorrectly configured the GPS?

[f5soh]

Time data means you receive at least one sat, next you need to download a valid almanac and finally get a couple of sats for position.
All this stuff is done by ublox module, not the LP firmware.

Starting a GPS for first time is always better outside, without buildings around.

[jtrout19]

My 6m gets a fix inside. Albeit not a good fix but a fix. My naza gps that I have gets a fix inside my house in like 30 seconds.

[TX21]

Time data means you receive at least one sat, next you need to download a valid almanac and finally get a couple of sats for position.
All this stuff is done by ublox module, not the LP firmware.

Starting a GPS for first time is always better outside, without buildings around.

I'm being told that there are 16 satellites in view

[f5soh]

In view but can be hidden or signal too distorted to be used.

[TX21]

Ah, ok. Is there any way to check the number of connected satellites then?

In view but can be hidden or signal too distorted to be used.

[f5soh]

The number of sats "connected" is displayed on PFD (upper/left corner) or GPS plugin (System tab) as "Sats used"

[TX21]

Both of these are displaying 0 yet the GPS is still receiving time data

The number of sats "connected" is displayed on PFD (upper/left corner) or GPS plugin (System tab) as "Sats used"

[f5soh]

Time data means you receive at least one sat to synchronize the clock. This same sat can disappear and the time data still.
For position you need to receive at least 3 or 4 sats correctly or the Ublox module do not compute the position.

[mpjf01]

The 6M never was rated highly as a good performer. I would replace it. I've been using two of these M8N for a while now and they are really great.

http://www.ebay.com.au/itm/Ublox-NEO-M8N-GPS-Module-with-Compass-for-APM2-6-APM2-8-Flight-Controller-AU-/252511077068?hash=item3acad542cc:g:wt8AAOSw6n5XvW9-

There's a cheaper version now I note, has a white ring on the case top. I've not tried it yet - maybe someone else has and can comment.

[Mateusz]

The 6M never was rated highly as a good performer. I would replace it. I've been using two of these M8N for a while now and they are really great.

http://www.ebay.com.au/itm/Ublox-NEO-M8N-GPS-Module-with-Compass-for-APM2-6-APM2-8-Flight-Controller-AU-/252511077068?hash=item3acad542cc:g:wt8AAOSw6n5XvW9-

There's a cheaper version now I note, has a white ring on the case top. I've not tried it yet - maybe someone else has and can comment.

I have 3 of those and they're really good.