You really should use a radio GCS (even if you are new)

I frequently read posts where folks 'think' their vehicle was in mode X or the battery was 'probably' getting low.  And then they crash...  Please read on for how to avoid this...

So the main reason I wrote Andropilot was that I wanted an easy way to know what was happening to my vehicle out at the field.

If you can afford to spend $100 and have an Android device, I think many of us would recommend that you run (not walk) to do the following things ;-):

  • Buy this (or the version appropriate for your country) ($85) (some small assembly will be required for this kit)
  • Buy this USB adapter ($2) (correct for most Androids, if not sure ask in the forum or read our wikis)
  • Download either Andropilot or Droidplanner (free!)
  • Plug in the radio
  • Start seeing live data from your vehicle

After you do this:

  • No longer will you need to remember 6 mode switch positions.  If you change modes from the tablet or radio, a voice will tell you what happens
  • If your vehicle enters a failsafe mode, your phone will tell you
  • You will always know where your vehicle is
  • If it is running low on power or doesn't see GPS, your phone will verbally warn you
  • As you come into land your phone will talk you through each altitude
  • If you want your vehicle to go somewhere, you click on the screen and choose GOTO.  etc...
  • You can draw a practice box and if your vehicle leaves it it will recover (plane only - see wiki instructions)

Sorry to be so blunt, but <$100 is a great added safety feature even for beginners...

Views: 4148

Comment by Stefan Gofferje on August 11, 2013 at 2:16pm

Nice concept, BUT...

I speak only for Europe because I don't know the regulations for the USA or other countries...

In Europe (except UK) you are limited to 10mW output power on 433MHz unless you have an amateur radio license or a special permit. 10mW is good for maybe 300m in direct line of sight and that's it. Depending on country (Germany is notably bad in this regard) you have radio amateurs who's only hobby seem to be to scan through the bands and report everything they think might be out of limits to the police or communication regulation authority, so if you operate with too high power on the ISM-band or go into the amateur band without a license, you pretty likely get in trouble...

I think, beginners should concentrate on mastering the vehicle and not start meddling with additional equipment. Especially multicopter have 4 or more very fast spinning propellers which can be quite dangerous, so unless you absolutely master your vehicle, keep your eyes and ears on the vehicle!

GCS software, especially Andropilot, definitely is very useful and can be a great help, when used properly. And if somebody finally would come up with a generally legal long-range telemetry radio system, it would be more than great :).

Comment by Hugues on August 11, 2013 at 2:30pm
I agree Kevin, i cannot imagine a flight without a GCS. If something goes wrong and the bird gets out of control or flies away, then a GCS is practically mandatory.

Comment by John Arne Birkeland on August 11, 2013 at 2:40pm

Stefan, I have a hard time believing you only get 300m on 10mW 433mhz, but that's not the point.

I am not advocating that you should break any radio regulations. But by your logic if you are following radio regulations, then you should also follow regulations in regard to R/C operated vehicles. In other words below 400ft and always LOS.

Comment by Kevin Hester on August 11, 2013 at 2:54pm

Hi Stefan, I totally agree - you need to be careful to use a frequency/power that is legal in your country.  So I don't know the details of Europe.

In the US the 915 band (at the power levels/frequency hopping used by default in the 3dr radio) is unlicensed.  So perfectly legal.  Someone else would have to chime in on Europe etc...

Comment by Adam Conway on August 11, 2013 at 3:04pm

Agreed the 300m is plain wrong unless you have a bad radio.  Mathematically you should get about 1/3 the range of a 20dBm (100mw) device if both devices are running at 900 MHz, however one is running at 433 which has the effect of adding the equivalent of 6 db to the SNR, this leaves a 4dB delta, you will be hard pressed to notice the difference in 4dB in regular flight.  To double check my work, I ran the Friis equation and got an SNR of 30 db at 1km, most 802.15.4 radios can run near zero dB SNR.

Otherwise really good post... 

Comment by Adam Conway on August 11, 2013 at 3:06pm

Oh and by the way Kevin - we should fly together... I fly at Baylands all the time!  I will "friend" you separately.

Comment by Stefan Gofferje on August 11, 2013 at 3:31pm

@John Arne:

Those regulations are not universal! German regulations are e.g. totally different and here in Finland, recreational model airplanes are not regulated at all. There simply is no regulation. Only commercial used RPAs have a 400ft AGL limit and must be piloted LOS. After receiving this statement from the Finnish Traffic Regulation Authority by email, I called the inspector who mailed me to double check. He said, there are some regulation changes being prepared but as of now, in Finland, a recreationally used model aircraft is not under any regulation whatsoever. The only regulation that applies is a general ban zone around airports and if you want to operate in regulated airspace, you have to check with your local ATC but that applies to pretty much everything that can move through the air, even fireworks at weddings and such.

But I agree, if there is such a regulation, one should obey it. Especially air traffic safety rules usually have good reasons and I for once wouldn't want to be responsible for hundreds of dead people by causing an air traffic incident. And as of now, we don't have TCAS or ADS-B for APM (wouldn't that be great? TCAS/ADS-B failsafe?)

And yeah - I did some tests and I got something like 320m before the telemetry link broke down. With the stock antennas. I didn't think further about it, because pretty much everything on 433MHz ISM you can buy says 100-300m range (garage-door opener, weather sensor, etc.). Using anything else but the stock antennas is also not easy, because the EU power limit is EIRP, not transmitter power. So you can't just plant a 4.5dB antenna on your radio and have more range.

Comment by Adam Conway on August 11, 2013 at 4:09pm

@stephan I think something is wrong with your TX/RX.  You should get more than 320m unless your Fresnel zone is being impinged upon, but even then...  fyi here is a description of a Fresnel zone  If you are testing on the ground, this could be your issue.

Comment by John Arne Birkeland on August 11, 2013 at 4:18pm

Stefan, do you by any chance have a RCTimer 433mhz radio with built in USB interface?

Comment by Stefan Gofferje on August 11, 2013 at 4:34pm

Yes, but I used 1 RCT air module and one 3DR air module for testing.


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