Cinestar Loses power during flight for a few seconds. Watch Video

Discussion in 'Cinestar 8' started by Chris Newman, Apr 27, 2013.

  1. Shaun Stanton

    Shaun Stanton Active Member

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    at first glance I would agree, you had the same issue, I had except you at least went into failsafe, which theoretically should have brought the copter home at least. Mine went into Egas, you did a better job in making sure your parameters were set approriatly for the flight. It is hard to say whether or not the power lines contributed to this. They could very well have, but I hate to jump to conclusions just because there are so many other factors that could cause this.

    One is I notice a industrial building to the north of you flight path. I cant tell, but maybe you know, is it a power transformer station?

    Another question, what RC controller do you sue and what was the power level?

    Lastly are you using a 900 Mhz TX for the gimbal?

    The answers to these questions can better help deduce, why yours went offline.

    I figure I would ask to eliminate other possibilities. I jump to conclusions on my own incident which turned out to be wrong.

    Cheers

    Shaun
     
  2. Cris Olariu

    Cris Olariu Member

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    Shaun -

    Indeed, I had the failsafe/ComeHome mode turned on, even though I never tested it (you know, by getting a heart attack while turning off the transmitter). But this is how I figured out it's working. In my video I can see how it jerked trying to come back home, but the picked up the signal again and allowed me to control it. The one thing that totally amazed me was the number of occurrences (47 times!!). Needless to say, I'm very happy I didn't crash. Here's the answer to your questions:
    I have no idea whether or not that is a power station, I haven't gone too close to it, but it is possible (there's a dam nearby, but it has no water in it, so if that's what it is for, I don't think it's functioning at the moment)
    I'm using a DX8, and that was the first flight after charging the batteries (I fly with 2 Quadpower 6200).
    I only have a 2-axis gimbal with no TX at the moment (except for controlling the roll from the DX8). I do plan however to get a 3-axis gimbal soon, and I should start looking into what Tx/Rx system to use.

    Cris
     
  3. Shaun Stanton

    Shaun Stanton Active Member

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    Cris, that is odd. It is possible that the power lines caused the disturbance, for sure. There could be a "Leaky line" Another possibility could be that you entered a natural dead spot as the poster a few back had mentioned. This can happen to you if the small wires are both horizontal as you go long distances, depending on where the DSMX satellite is mounted. If your antenna is mounted to the side of the copter on the 3rd or 7th boom side and you are flying away from you. If the slant distance from your perspective to the copter is shallow then you can enter the "Dead Zone," or "Cone of Silence" of the radio wave. If the wires are situated that if you are staring straight down the cylindrical part of the antenna then you will be in that cone. A way to mitigate it is to bend one wire vertical, so that there is always bringing the wave towards you.

    Here is my "caveman artwork" of the principle.

    antenna.jpg
    Of course I do not want to misdirect you on your specific incident. When it comes to radios. Sometimes the answer is all of the above. In your case the power lines could have contributed to disrupting the signal. As the copter got far away it was just enough to disrupt the incoming signal. There could have been multiple factors. The copters own electronics and power off of the motors. The video down link you are using coupled with there were a lot of houses in the area, most likely with WiFi Hot spots, some may have higher gain antennas. All of the factors combined could be causal versus one alone.

    One way to mitigate it is to do a signal test on your DX8. You get it through the start-up menu. You need to momentarily disconnect the T-1000 telemetry module. The way it works is when you get to the signal test menu you press the trainer button. What this does is lower the power from your DX8. You can put the copter at a distance from your launch spot by hand and test if the signal starts getting disrupted. There is a procedure in the DX8 manual to do this. This will give you an idea if you will loose signal during the flight. It is not full proof, but it is better than nothing.

    Shaun
     
  4. Cris Olariu

    Cris Olariu Member

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    Great insight Shaun, thank you. I'll follow your advice and turn one of the antennas vertically. That could very well be the reason. I have always wondered why the DSMX antennas are so small, and if people have done anything to extend them.
    Funny you mention the Range Test. That exact morning I did such a test, right before that flight. It was the first time I did such test. It was all successful. I had full control of the copter (had my friend restrain it on the ground). The one thing I didn't do, however, was to disconnect the T-1000. I'll try that next time.
    Thanks again for your detailed explanation.
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Cris: How quickly after doing the range test did you take off? I'm just wondering for how long after enabling Range Test on the transmitter the RF output remains attenuated?

    Andy.
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If you're using a Spektrum transmitter (unlike others that use a time delay), the Spektrum needs to have Range Check enabled, and then you hold the Trainer switch to reduce the RF output -- so you couldn't have possibly taken off with reduced RF power. :)

    Sorry..
    Andy.
     
  7. Cris Olariu

    Cris Olariu Member

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    That would totally suck. I'd say I flew within 2-3 minutes from the Range Test. But I took off just fine. Here's the GPX that was recorded during the Range test.
     

    Attached Files:

  8. Shaun Stanton

    Shaun Stanton Active Member

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    No problem:)

    For the most part they are fairly resilient radios. It would be hard to really modify them without damaging the radio. Radios at 2.4GhZ are frequencies inside the microwave spectrum. It is much more difficult when dealing with radios in this spectrum. Because these radios are so small they have been engineered specifically for the correct impedance and gain for the type of circuitry in the radio. Increasing the gain on these tiny radios would be hard to do without messing up their performance. In order to do it you would have to have some intermediary device to ensure that the circuit is not over gained. Too much gain on the circuit can cause the wave form to distort, a phenomena you probably may have heard with audio equipment called clipping, in some case burn out the radio circuitry.

    Unfortunately, I don't think these satellites were intended to be standalone devices, they were meant to be used in conjunction with Spektrum or JR receivers. They were meant to be a redundant receiver for the Spektrum AR8000 or other type of device, that radio you had to use to bind your satellite with your controller. The purpose was for them to backup the signal on the AR8000 or similar devices. There is this product out there http://www.quadrocopter.com/Diversity-Controller-for-Spektrum-and-Jeti_p_344.html. It will allow you to put up to 4 independent satellites on one board. I bought one, but have not installed it. The verdict is still out on how effective they are. They choose the satellite with the strongest signal, it is uncertain if that is the one with best signal. In digital communications there is a distinction between signal strength and signal quality. A radio with a stronger but noisier signal, may not be better than a radio with a weaker but less noisy signal.

    I found with my radio, that while the T-1000 was connected it never indicated to me that the radio was in low power. I have old firmware on my radio, I am dealing with Spektrum or Horizon Hobby I think for a few months to register the radio, to get the latest firmware. Apparently some radio serial numbers never reached the data base. So if yours says the radio is low power when you touch the button then it may be doing the test adequately. It should cay low power on your LCD when you press the button.

    Shaun
     
  9. Cris Olariu

    Cris Olariu Member

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    Shaun, you are full of great knowledge man! If you ever get to install that diversity controller, I'd be interested in your results.
    I'm pretty sure my radio said low power on the screen when I did the test, so maybe I'm ok. I'll still give it a try without the T-1000 next time.
    Thanks again!
     
  10. Shaun Stanton

    Shaun Stanton Active Member

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    Thanks,

    One day I will get an extra DSMX and try it out. I think if I do try I will only add one more Sat. Four seems a bit overkill:)
     
  11. Andrew Goodwin

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    Hey Guys, I watched this footage and really just couldn't believe this was even being attempted. Over an active roadway in a downtown core. I don't know, you guys in the U.S. I guess are breaking the law no matter what you do with these things right? But damn, that seems like a crazy place a to fly. Just my two cents :)
     
  12. Sean Haverstock

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    Not to get to far off topic, but what is the protocol for power lines? Throughout the forums there seems to be varying opinions on their effect on radio signal. People claim to fly near them often and I see videos of people flying in densely populated areas often, too. It sounds like you have to take the GPS off but what's the story with radio interference.
     
  13. Gary Haynes

    Gary Haynes Administrator
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    Sean there are to many variables to give a solid answer. Videos you see could be with 2.4Ghz or 70cm or some other type of radio freq. Normal transmission lines like those into the house or along the street shouldn't be a problem. 100KV lines and up, the ones on the big towers, probably more of an issue. The EMI off of them is enough that you can stand under them with a fluorescent tube light bulb and have it start glowing.
     
  14. Shaun Stanton

    Shaun Stanton Active Member

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    I agree with Gary on this one. I used to rent a studio in an industrial area. Our building had power lines orbiting it all over the place. I never really had too much interference. I used to test fly on top of the roof and never had too much of an issue. If I got the copter close to the line I might experienced a little "nose hunting" from the magnetometer, but not enough to really set the compass error off. But like anything if it is a new area it is always good to check to see if the lines could cause some interference.
     
  15. Gary Kaplan

    Gary Kaplan New Member

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    I have to step in here guys. There is so much misinformation in the hobby and in this forum that I feel like I have to help out. There are people in this forum who make wild assumptions about why something crashed, why something glitched, why motors are hot, ect. etc. etc.. If you do not properly test the area you intend to fly in then you absolutely know nothing about what caused a failure. If you put together your quad, hex or oct and you dont test the signal level coming and going out of each system (flight control, GPS, RC Tx/Rx, FPV, etc.) then you will crash. Hopefully you just lose $10,000+ (or more) rig and camera and no one gets hurt in the process. But it doesn't need to happen in the first place. Let me explain and let me share a bit of information. What helps eliminate the possibly of crashing? Knowledge and Experience. That's its. If you are not knowledable about the area you intend to fly in and you don't have the experience to know how to tune, monitor and troubleshoot your rig (from an electrical and mechanical point of view) then you will crash. Its just a matter of time.

    Before any of my rotors turn I do a complete RF analysis of my flight area. Why? My gear is very expensive and I don't want to have to replace it. Also, I couldn't live with myself if someone got hurt as a result of my helicopters or airplanes. So, as a matter of re-flight check I look at the ENTIRE RF spectrum of the equipment and flight rig I am using (airplane or helicopter) and others around me may be using. That means a sweep from 630~680MHz (UHF FPV, wireless audio, etc.), 900MHz (low end FPV Tx gear) to 1.2GHz (GPS reception and FPV Tx/Rx gear), 1.3Ghz (FPV), 1.9GHz (GSM phone), 2.0GHz ( LTE 4G cell phone and microwave communication), 2.4GHz (WiFi, RC Tx/Rx, PFV), 5.8GHz (FPV and 802.11), etc. You get the point. I get jobs by understanding that safety comes first, above all else. I know the waters I intend to swin in VERY well before getting in the water. This is what I am talking about (below).

    If you do not do this then you are risking more than just the cost of a new heli and camera. Not to mention there are many people who just cannot fly. They rely on GPS and station hold to get them by. Best advice is STOP taking UAV jobs and go join the AMA and a local RC club and spend the time learning to fly at an AMA approved field. You have to know how to handle all of the orientations and forward flight first above all else. Gain solid understand of the systems (electrical and mechanical) and be able to maintain and troubleshoot the gear. Its no trivial matter buts its very important to do the work first, before you fly. It takes time but you will be better off in the long run.

    802.11 (4 channels being broadcast)
    View attachment 1973

    (GSM1900 Cell Phone)
    View attachment 1974

    (LTE-4G Cell Phone)
    View attachment 1975

    (5.8GHz. Nothing Tx'ing at 5.8GHz but something "unknown" at 5.4GHz)
    View attachment 1976
     
    Steve Maller likes this.
  16. Gary Kaplan

    Gary Kaplan New Member

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    802.11 (4 channels being broadcast)
    80211 Scan Example.png

    (GSM1900 Cell Phone)
    GSM Scan Example.png

    (LTE-4G Cell Phone)
    LTE 4G Scan Example.png

    (5.8GHz. Nothing Tx'ing at 5.8GHz but something "unknown" at 5.4GHz)
    58GHz Scan Example.png
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    GaryK:
    What software/hardware are you using to get the data you show in the images, please?

    Also, how best to deal with the fact that the spectrum you sample at ground level at the launch point might be quite different from what the copter "sees" when it's a 200 feet above the launch point? Obviously there may be some correlation, but also there's the issue that the copter now has much greater line of sight to more possible transmission sources that you might not be able to detect on the ground.

    Clearly if the spectrum is cluttered while you're on the ground, that doesn't bode well for flying -- but do you see the converse where the ground-based view of the spectrum is clean, but the airborne view is cluttered?

    Thanks
    Andy.
     
  18. Gary Kaplan

    Gary Kaplan New Member

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    Andy,

    Its a portable spectrum analyzer covering 10MHz~6GHz. These are just examples. You take multiple readings at the location of the pilot, then walk the flight path and measure at any special places you will fly to. Such as the example in another thread where the pilot flew over to a bridge and then the heli crashed. I would never fly to a location I didn't test first. Also, use a omni directional antenna first to get a general idea of what is around and then switch to a directional antenna which will tell you where a signal is coming from, where it is strongest and where it is weakest. You have to first know what you are looking at on the analyzer and whether what you see is a threat or not. Signal level and noise floor are the two biggest issues to deal with first.

    Gary
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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  20. Gary Kaplan

    Gary Kaplan New Member

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    Thats my baby. But don't buy it from anyone but Kaltman. If you buy it from a non-authorized source it won't be covered by warranty and you cannot get technical support. Get the higher capacity battery and 12V car adapter and audio level indicator options. It'll set you back a pretty penny but well worth the investment.

    http://www.aaroniausa.com/

    RF signals propegate in all directions. What you measure at ground level is very close to what the heli will "see" in the air. But if you have the ability to go up to heli altitude such as the roof of a building you are shooting then take another set of measurements there to confirm what you see. It may be different, but if you use the directional antenna you can also tell a great deal about the environment.

    At our club airfield I found a spot where 2.4GHz was severely attenuated and an area where there was a large spike in 802.11g OFDM (where someone close by was illegally transmitting at high gain to reach across his ranch). Until I tested veterans called it the "devils triangle" where planes crashed without warning from time to time. Remember, the RC transmitter is FHSS (Frequency hopping spread spectrum). The Tx you hold and the Rx in the heli/plane talk to each other and lock onto a unique free frequency/channel within the 2.4GHz band that no other pair shares but they will hop over to a new channel if adjacent noise levels become to large (such as direct interference from WiFi or a harmonic from another technology such as 1.2GHz FPV or even 5.8GHz 802.11 or FPV gear), but the control signals (pitch, yam and roll) are spread across the entire spectrum that every other piece of 2.4GHz gear is using. This includes 802.11, wireless phones, and a bunch of other unregulated wireless equipment and products.

    Gary
     

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