U-Blox 7 GPS - Lights

[gravityguy]

Hi all,

I finally got my last bit of kit last night for the build which I duly completed. I managed to activate it and connected to my iPad but no GPS signal was found. I did give it about 20 minutes (placed half in and half out of my window) but still nothing. There were also no lights flashing on the gps system. Should I be seeing the lights doing something when it is searching for satellites or does it only do this once it has picked up a lock?

Maybe I was just being impatient but not seeing any lights on the gps didn't fill me with confidence.

Sorry of this has been covered previously, I did do a search but couldn't see anything that was relevant.

Mike

[ianfallon]

IIRC I think it blinks green when it's got some level of lock and not before then.

I'd strongly advise running it outside with as full a view of the sky as possible.

[gravityguy]

Thanks Ian,

I'll give it a try tonight once I've reloaded my new sd card with the firmware (my first stopped working after about 30 minutes but I think this was due to the poor power lead I was using - it kept coming loose - so constantly restarting).

[Paul_Sengupta]

These GPSs seem to be pretty deaf. I've had mine on my windowsill upstairs for a while now and maybe a quarter to a third of the time it gets no lock. On the other hand the built in GPS circuits in my tablets and phones can quite easily get a signal downstairs near the window, upstairs anywhere, and with a bit of waiting, even downstairs on my sofa sometimes! On the windowsill the U-Blox seems to pick up 3 or 4 satellites at the most, whereas the tablet's GPS in the same spot will pick up many more.

I've got two of these GPSs and I've tried both, and neither appear to be better or worse than the other. The position also wanders around a bit, it's been described on here before as having a ground speed of between 2 and 4 knots all the time.

So try it out in the open.

[ianfallon]

GPS really doesn't work well indoors. Given a proper outdoor view of the sky I've not have any problems with GPS reception.
"Near a window" doesn't cut it 

[colinmackenzie]

My one took ages to get a lock on my window sill, when it eventually did, I managed to pick up 9 satellites!

[bnmont]

How do you tell how many satellites are being seen.

Thanks Brian

[Admin]

How do you tell how many satellites are being seen.

Thanks Brian

Hi Brian

Take a look at the web page 192.168.1.1, it reports the status of all the interfaces
Thx
Lee

[T67M]

These GPSs seem to be pretty deaf. I've had mine on my windowsill upstairs for a while now and maybe a quarter to a third of the time it gets no lock. On the other hand the built in GPS circuits in my tablets and phones can quite easily get a signal downstairs near the window, upstairs anywhere, and with a bit of waiting, even downstairs on my sofa sometimes! On the windowsill the U-Blox seems to pick up 3 or 4 satellites at the most, whereas the tablet's GPS in the same spot will pick up many more.

I also have a Ublox-7, and I find it is a better pure-GPS/GLONASS receiver than the one in my phone, however the phone "cheats" by also using nearby WiFi SSIDs and cellphone triangulation to acquire lock more quickly. Also the phone is never turned off, so it always has a complete GPS almanac available - the Ublox can only download the almanac when it's turned on, and thus it can quickly become stale, especially if it's moved while turned off. Downloading the entire almanac (a "cold start") can take half an hour, requires a very good sky view (80%+) and often has several "false starts" before getting a solid lock. With a valid almanac and in the same general area as it was last used (a "warm start"), my Ublox gets a solid lock within a few seconds with a ~50% skyview.

As stated elsewhere, when the Ublox has a good GPS lock, the LED flashes green. Until that time, the LED stays off.

[the_top_pilot]

I run 2 Ublox-7's pretty happy with both.

GPS units made in the far East tend to have a 'Almanac' that is looking for satellites it expects to see over the far East.  it can't see over Europe when it expects to see them.
As a result at first time power up thousands of miles from where it expects to be can take a time for it to find itself.
Give it a fair chance by giving it the best view of the sky it can

Steve

[chrismills]

In general this is good advice however, the suggestion that your phone cheats is not strictly true. If you have an android device and your using my PilotAwareAndroid app to provide position data then this ONLY uses gps. This is specifically coded in the software. Wifi and 3g are not used, even if they are connected.
ChrisM

[gravityguy]

I got it all working last night after using a new sd card. The gps locked on to the satellites within about 2 minutes. I didn't pick anything up any aircraft though. I do however live at the bottom of a deep depression meaning a limited view of the sky.

If the weather improves later. I'll take it somewhere with a good view of the sky.

One thing I am wondering however is the power requirement for the unit. I have an EC Technology 22,400mAh power bank which has both 1A and 2A outputs. On the first boot (where my sd card died) I was using the 2A and yesterday I used the 1A output. I'm wondering whether thre2A output was just to much for the unit to take and thereby destroying the sd card? Or does RPi recognise the power and adjust accordingly like a mobile phone would?

I also noticed that the DVB-T dongle was getting extremely hot after only a few minutes (using the 1A output). Is this normal?

[Ian Melville]

Stick with the 2A output.
The device plugged in only takes the power it needs, whatever the rating of the port. In the case of the 2A output it can supply the needs of a device up to 2A. If you try to draw more the voltage may drop, and in extreme cases you may let the smoke out. Using the up-to 1A output may also cause the Pi to reboot if it needs more than 1A

Hot DVB-T dongles are normal, though less than ideal. IIRC someone was looking at ways to cool them to preserve long life, of the dongle.

[ianfallon]

The word "Almanac" is great isn't it ? 

[gravityguy]

Success - I have picked up my first few aircraft. They are all commercial aircraft but that's not surprising given the current weather. I set it up outside in a hydro sealed container (Tupperware box  ) and it worked like a charm