[Paparazzi-devel] YNT: interference problem

[Refik Sever]

Dear Markus,
Thank you very much for your explanations. I will try to answer your questions:

>Did your aircraft crash or execute the failsafe (it was in auto2, right?)?
 >What failsafes did you program?

The failsafe was programmed to give a 0.3 throttle and constant roll. It did not execute failsafe. Rather, the autopilot was freezed. It stopped sending telemetry. Our GCS is far from GSM tower, normally we always get telemetry. Therefore, I think that the autopilot was confused.  It crashed.

  >Are you using XBee (the 2.4 GHz ones)?
        Yes.
  >Do you experience the same problem in manual mode?
      It does not occur frequently. It occurred for the 2nd time in 200 flights. The GSM base is in our university campus. In summer, the campus was empty, now it is very crowded. It may changed the radiation power from the base station.
  >What do you mean by "GSM base station" exactly?
      It is a GSM base station tower around 80m. In Turkey, GSM frequencies are 900MHz and 1800Mhz. I don't know if it contains another radio link.
  >Note that some of the stations might have additional active antennas, ie. not for the GSM service itself, mounted on them.
  >How far away from the base station is "near the base station"? (10 m :o ? 20 m?)
      The distance between plane and tower was around 50-60m when the crash occurred.
 
I will try to shield the board and cables. I want to be sure that it will never happen again. I am planning to test it in a laboratory and observe the effects of shielding. I will send the results.

Best regards,
Refik

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Kimden: Markus Bina address@hidden adına paparazzi-devel-bounces+address@hidden [paparazzi-devel-bounces+address@hidden
Gönderildi: 27 Eylül 2013 Cuma 22:07
Kime: address@hidden
Konu: Re: [Paparazzi-devel] interference problem

Hi.

I try to help by asking you a few questions  ... hopefully it helps you to narrow the problem down:
  Did your aircraft crash or execute the failsafe (it was in auto2, right?)?
  What failsafes did you program?
  Are you using XBee (the 2.4 GHz ones)?
  Do you experience the same problem in manual mode?
  What do you mean by "GSM base station" exactly?
  Note that some of the stations might have additional active antennas, ie. not for the GSM service itself, mounted on them.
  How far away from the base station is "near the base station"? (10 m :o ? 20 m?)
  What else is mounted on that base station?

In case it is really interference from the GSM signal (that does not trigger any failsafe) I'd first try:
1) not flying near that base station ;) ... do your flight tests somewhere else entirely (no other transmitters), if the problem reappears it was not due to the GSM base station...
2) Fly in manual mode near the base station; does "it" happen again? Can you reliably reproduce the "effect" of loosing the telemetry?
3) using ferrite cores ... How long are your cables (to/from servos, xbee, etc, ...) in the aircraft? Are you using selfmade antennas?
4) in desperation: "shielding" board and wires

Hope this helps you to find the problem.

Cheers,
 Markus



Am 26.09.2013 23:17, schrieb Eduardo lavratti:

The SPEKTRUM radio ever stop near GSM base

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From: address@hidden
To: address@hidden
Date: Thu, 26 Sep 2013 22:50:22 +0300
Subject: [Paparazzi-devel] interference problem

Dear all,

 

We are performing flight tests in front of a GSM base station. Yesterday, our autopilot (Lisa-M) stopped working just near the base station. It stopped sending telemetry, and I couldn't switch to auto1 and manuel modes. 2 months ago, we were using umarim_lite, and at the same position it also stopped working. At that time, we thought that GPS signal was lost and it went to failsafe.  But now, we think that autopilot stopped working due to interference from base station.

 

Did anyone encounter with interference problems? Or, did anyone test the EMI-EMC compatibility of Lisa-M in a laboratory? Do you suggest to shield the autopilot with metal foil?

 

We have an unreflecting test room in our department. I will try to test the autopilot for EMC.

 

Regards,

Refik

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