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May 31, 2015, 02:41 PM
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Quote:
Originally Posted by Jackanory
Hi, would like to know if anybody else has got the same problem, using ULRS with APM 2.6 and Mission Planner 1.3.25.

Can connect with 19200 baud, artificial horizon battery voltage etc. updates- problem is parameters do not load, no problem press cancel or ctrl-T.

Next problem message pops up failed to set home position - even though I have 3d fix?

also cant read or write way points to APM.

ok so plugged in 3dr radio, can now get parameters and read / write way points to apm, even with GPS unplugged.

I have checked, double checked and checked again that TX RX telemetry connections are correct.

searched internet but can not find a solution.




Tried several different APM Modules all acting exactly the same.

I have found the solution to the problem!! , tried everything imaginable but would not work for me until i connected the negative wire from my telemetry port as well, this was the case on both of my APM units a chinese clone and HKpilot.

after connecting everything worked!!

Is something wrong with my setup, why does it work without the ground wire for other people?

Thanks for all the support so far, massive thumbs up for ULRS, just waiting on DTFUHF fuctionality.
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May 31, 2015, 03:18 PM
Registered User
Thread OP
It's nice you can connect, but can you modify parameters ? It seems that something has changed in recent mission planner versions, you should stick with MP version 1.3.15 for now (I've update www.itluxembourg.lu/site with a link to the last good version)

It seems that it works with 3DR radios, so probably it's a change that uses AT commands or something specific to 3DR radios.
Jun 03, 2015, 09:17 PM
Wisconsin
Quote:
Originally Posted by flipflap
It's nice you can connect, but can you modify parameters ? It seems that something has changed in recent mission planner versions, you should stick with MP version 1.3.15 for now (I've update www.itluxembourg.lu/site with a link to the last good version)

It seems that it works with 3DR radios, so probably it's a change that uses AT commands or something specific to 3DR radios.
I have had no problem with 3.1.25,26,27,28 FlipFlap. Do you have a specific sequence/parameter you want me to test? Are you testing with ArduPilot or Arducopter?
Last edited by mike_kelly; Jun 04, 2015 at 10:15 AM.
Jun 04, 2015, 06:12 AM
Registered User
sea_owl's Avatar
3DR radio use ECC (error correction code). This ECC adds link reliability (and distance), with the price of overall data traffic and latency. Please, does ULRS use some kind of ECC in data transmission?
Jun 04, 2015, 07:11 AM
Registered User
Thread OP
I didn't implement a forward error correction such as Golay in ULRS, because it would reduce the throughput. I consider this is useful for some applications where any missing packet is visible such as HDTV transmission.

But here the loss of several packets is invisible : maybe the transmission of a packet containing GPS position will be delayed by 100 ms and that's it. In addition given the ULRS power is "1W", it has many less lost packets, and much higher range than a "100mW" system such as the 3DR radio.

But I'm curious and could consider trying a Golay FCC.

Have a look at this for a comparison of ULRS and 3DR : http://www.itluxembourg.lu/site/ulti...-or-3dr-radio/

Notice that the 3DR implementation of Golay is very costly : the actual baudrate is halved, and it only allows to correct 3 bits over every 12 bits group :
http://www.engr.mun.ca/~bachmayer/en...ts/3DRadio.pdf
Last edited by flipflap; Jun 04, 2015 at 07:18 AM.
Jun 04, 2015, 07:18 AM
Registered User
Thread OP
Quote:
Originally Posted by mike_kelly
I have had no problem with 3.1.25,25.27,28 FlipFlap. Do you have a specific sequence/parameter you want me to test? Are you testing with ArduPilot or Arducopter?
OK good news, I'll check my APM firmware version too.
Jun 04, 2015, 06:58 PM
Registered User
Quote:
Originally Posted by flipflap
Notice that the 3DR implementation of Golay is very costly : the actual baudrate is halved, and it only allows to correct 3 bits over every 12 bits group :
http://www.engr.mun.ca/~bachmayer/en...ts/3DRadio.pdf
FEC is a terrible idea for realtime streams like this. You have all that overhead just to reconstruct an old packet. Far better to just wait a fraction of a sec for a new packet.

If you have to run at twice the baud rate to run the FEC it's also going to cause a lot more bad packets than you would have had running at a slower speed. Even if the FEC corrects most of those it still doesn't take into account the increase in totally bad packets that can't be reconstructed.
Jun 07, 2015, 03:48 PM
Registered User
Quote:
Originally Posted by flipflap
Yes this is the OrangeRX weak spot, I recommend to always change the coax cable.

I've documented this issue here, with reference to a replacement cable : http://www.itluxembourg.lu/site/hobb...z-modules-faq/

It also describes where to solder directly on the RFM pins a much more resistant RG58 ohms coax cable.
I have to add a WOW too here.
I just maidened my new SkyHunter today and Im lucky that I didnt crash it. Started to loose radio at 300ft. When it completely went out it started to bank right (because I forgot to setup the failsafe) thank goodness because it glided close enough to me that I could regain control and land it.

So I get home and I am tearing the plane apart. I find that not one, but both rf connectors in both TX (one acting as RX) are damaged. Did this by Ohming out the cables. The one in my transmitter both conductors are no good and the one in my plane only the center conductor is good unless I stretch it out then both conductors are good.

HOAKY! Especially because I made it 1 mile in my penguin with this same gear.

One other issue Flipflap.
When I launched the plane I backed up over my 9ft USB cable and pulled it from the PC. When I reattached it (after landing) it resets the TX connection and take 6 seconds to reestablish. I tested this in various ways but every time you reconnect the USB cable you loose complete control of the plane for 6 seconds. Is this normal?

Thanks.
Last edited by analogman; Jun 07, 2015 at 04:45 PM. Reason: Add info
Jun 07, 2015, 03:54 PM
Registered User
Here is a link to my setup
https://www.rcgroups.com/forums/show...2#post31825184

Ill put a video of the flight up shortly.
Jun 07, 2015, 05:00 PM
Registered User
Thread OP
Quote:
Originally Posted by analogman
HOAKY! Especially because I made it 1 mile in my penguin with this same gear.

One other issue Flipflap.
When I launched the plane I backed up over my 9ft USB cable and pulled it from the PC. When I reattached it (after landing) it resets the TX connection and take 6 seconds to reestablish. I tested this in various ways but every time you reconnect the USB cable you loose complete control of the plane for 6 seconds. Is this normal?
.
So you made 1 mile with damaged antenna cables, that's rather good

When you reconnect the USB cable, it makes a reset of the atmega, except if you disconnect the DTR pin, but then it wouldn't be possible to program with this cable. But 6 seconds seems long, I'll try tomorrow.
Jun 07, 2015, 05:19 PM
Registered User
Quote:
Originally Posted by flipflap
So you made 1 mile with damaged antenna cables, that's rather good

When you reconnect the USB cable, it makes a reset of the atmega, except if you disconnect the DTR pin, but then it wouldn't be possible to program with this cable. But 6 seconds seems long, I'll try tomorrow.
If you do not have the same results please let me know and I will make a video. I will remove the DTR and try again. If that is all that is needed then a disclaimer would be good.

I think the cable got damaged when I added the 3D printed cover to the OrangeRx module in my transmitter. I was not rough with it which is a testament to their fragileness.
Jun 07, 2015, 08:32 PM
Registered User
Quote:
Originally Posted by flipflap
When you reconnect the USB cable, it makes a reset of the atmega,
That doesn't make sense. Is this a hardware or software bug?

Quote:
Originally Posted by analogman
I just maidened my new SkyHunter today and Im lucky that I didnt crash it. Started to loose radio at 300ft.
[...]
HOAKY! Especially because I made it 1 mile in my penguin with this same gear.
That seems pretty typical for what has been reported. The fake "1W" units don't seem to be preforming nearly as well as 100mW units. But I find it hard to believe that bad cables/connectors are responsible for all this trouble.

Any clue what's really going on?
Jun 07, 2015, 11:17 PM
Registered User
Thread OP
Quote:
Originally Posted by analogman
If you do not have the same results please let me know and I will make a video. I will remove the DTR and try again. If that is all that is needed then a disclaimer would be good.

I think the cable got damaged when I added the 3D printed cover to the OrangeRx module in my transmitter. I was not rough with it which is a testament to their fragileness.
OK I tested it, when disconnecting the USB, the TX gets a reset : this is due to the way the DTR pin is used to trigger a reset on arduino boards, and OrangeRX. See for example this thread about a normal arduino board which gets reset when the USB cable is disconnected.

But the reset takes about 1 second, so for example if I put the stick on the right, then disconnect the USB cable, the TX will make the triple bip, showing that it's reset, and the servo will be for one second in failsafe position.
Last edited by flipflap; Jun 07, 2015 at 11:33 PM.
Jun 08, 2015, 04:52 AM
Registered User
Looks like there is a simple fix then. Just cut the DTR to reset line.
Jun 08, 2015, 09:38 AM
Registered User
Quote:
Originally Posted by flipflap
OK I tested it, when disconnecting the USB, the TX gets a reset : this is due to the way the DTR pin is used to trigger a reset on arduino boards, and OrangeRX. See for example this thread about a normal arduino board which gets reset when the USB cable is disconnected.

But the reset takes about 1 second, so for example if I put the stick on the right, then disconnect the USB cable, the TX will make the triple bip, showing that it's reset, and the servo will be for one second in failsafe position.
I agree with the USB disconnect, but the 6 second reconnect is when you plug the USB cable back into the computer after it falls out.

Also, I updated my blog with a video from yesterday. Because I tripped on my USB cable I do not have telemetry logs from the flight. I must have tripped on it as I launched the plane.
https://www.rcgroups.com/forums/member.php?u=528502


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