No GPS lock with ArduPlane

Navio / Edge Hardware
1

Hi,

I don’t have much information at this point. I took my new Navio+ out to the field to fly, and I couldn’t get a lock. Everything else seems fine, just no GPS. I followed the docs on auto-starting the software, but no luck.

Are there other required steps?

Thanks,
Chris

2

Hello Chris,

Have you connected the GPS antenna?
Can you post a picture of your setup?

3

Yep, I was using the antenna that came with the kit. It was outside of the aircraft pointing up.

I’ve removed everything from the aircraft to debug, but I’ve attached a picture of that.

Thanks, Chris

4

What is the gps status in the GCS? Is it “1” or “0” ?

It might take up to 10 min to get a lock in a new location, another reason might be interference with some equipment on board.

The best way to debug and improve GPS positioning is by connecting to u-center software as shown in the docs and observing SNR levels. You should have 4-5 sats with SNR around 45+.

5

GCS status is 1. I left it out for about 30 minutes without a lock. I’ll check with the u-center software now to see what’s happening.

-Chris

6

This is most likely some kind of interference issue, try moving antenna as far from everything as possible and also leave only necessary equipment for the test connected.

We just had a case with a damaged antenna cable where it connects to the antenna, so this is also an option.

7

I still haven’t had any luck. For now, if I plug in an external GPS, how do I configure Arduplane to use the external GPS signal?

I plan to do some more serious debugging of the GPS issue in the morning. I’ll provide they information once I have it.

Thanks for the awesome support. I’m sold on this platform. I’ll be ordering at least one more shortly.

8

Ok, I spend some time looking into what’s going on. I can now get a lock occasionally. I believe that there is an issue with the cable at the connector. Wiggling that connection, while keeping the connector to the to board stationary, results in a loss of GPS signal. Can you provide the specifications on the antenna so I can buy a spare?

9

@capucsc, this is weird. Could you please make sure that you are not moving the antenna to or away from some source of noise when bending the cable?

The antenna is L1 GPS/Glonass with MCX connector, but we will send you a replacement if this one is the problem.

Could you try connecting to u-center, fix the antenna and Navio and only bend the cable. Would it result in a fix loss or significant drop of SNRs?

10

@capucsc Have you tested with our .deb or compiled the code yourself?

11

@ivereninov – using the .deb on a RP2.

12

Could you please try to make sure that the source of the problem in your case is antenna fault? Then we can issue you a replacement.

13

Hi Igor,

Sorry for taking so long to get to this. I’m now doubt that this was an antenna issue. I’ve now three separate antennas, and all respond the same.

I sent the aircraft out for a flight (manual only), and have attached the plot of the number of visible satellites. It fluctuates wildly.

I then SSHed into the plane on the ground and monitored the GPS using u-Center. I saw the same fluctuations in the GPS sats. This is the same across the two antennas I tested. Photos are attached.

Any thoughts?

-Chris



14

The other odd thing is that u-Center reports a lock, but when I kill the GPS process and re-run ArduPlane, it reports no lock.

15

@igor.vereninov – I wanted to check in on this. What should my next steps be?

16

@capucsc could you please make the following test: Under open sky turn Navio+ on and connect to u-center. Observe SNR levels, you should see 4-5 satellites around 40 dBHz. If not, try to move the antenna around, do not place it directly on the Pi. If nothing changes, your antenna might be faulty.

If in this test you will see same SNRs as on your screenshots, PM me and we will issue an antenna replacement.

17

Oh, now I read the topic again and it looks like you have tested several antennas already. Was it under open sky condition?

Well, then let’s try to replace your Navio+ and see if that makes difference. Could you please PM me your order number?

18

Hi Igor, i m following this post cause i have exactly the same issue with the GPS, i have two antennas and two navio+ boards. I never had a GPS lock, tested with 2 antennas on each boards and with the VTX off.

19

For future reference and reporting GPS lock issues. To determine whether your GPS works or not, make a separated test. Take your Navio+ and RPI to an open area (field, park, backyard) where multiple satellites are visible. Connect antenna, connect to u-center software as shown in the docs and wait for 3-5 minutes (usually 40s would be enough).

Here is what your SNR levels should look like, or better:

It is very important that you place the antenna as far away from RPi as the cable allows and that you do not have any other equipment connected while performing tests (no 3G/4G modems, no cameras etc. )

@florent451 hmm… it would be a very unrealistic scenarios with two faulty boards at once. Are you sure there is no other equipment running that might create interference? Could you test it not on the copter as described above?

20

@ivereninov – I just ordered a second board. I’ll do a comparison later today (if the rain lets up) or tomorrow. Hopefully the new board solves the problem. Thanks for the example, I’ll know what to look for.

-Chris