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Old Jan 20, 2015, 01:46 PM
Registered User
London, ON, Canada
Joined Nov 2010
75 Posts
Quote:
Originally Posted by Nathaimu View Post
Hi everyone.
I am building a pretty big hexacopter that carries a GH4 camera on an Align gimbal. It is a custom build, so the pieces don't always fit together, but so far everything found its place, and the hexa flies pretty great.

Just to be clear, here is a basic description of what I am using at this point :
- Wookong M
- Graupner MZ18 radio and GR24 Rx
- 16000MAh 6S battery
- 3S battery as secondary
Pretty simple...

Still left to add to the system :
- Lightbridge
- Gimbal and camera

As I said, in this configuration, and with no gimbal or Lightbridge, the Hexa flies perfect, but my problems start when I use the LB Air Sytem as a receiver. When I do that, the hexa "stutters", or coughs if you prefer. I would not dare to fly it.
So just to be clear, when I use the lightbridge (and UNplug the GR24 Rx), everything responds fine, everything is calibrated in LB and Wookong, motors start as they should, but while the motors are working, I can see and hear small "jumps". It is as if the system stops for a millisecond and starts again, like little coughs, or some kind of irregular jitter.

Has anyone experienced something similar ?
quick question on your radio setup before I answer my guess as to what's happening. For your throttle, is it centered with spring tension to re-center similar to other stick?
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Old Jan 21, 2015, 07:12 PM
DJI Support
Las Vegas/Lake Tahoe
Joined Feb 2010
11,467 Posts
Quote:
Originally Posted by AlchemistAerials View Post
Not sure if I can post this here or if it was already addressed. I shoot mostly fast action aerials, car chases, car commercials, speed boats eyc, I was holding out on buying a lightbridge because of latency issues. I only fly about 1000ft away most of the time.

Have any of the new updates improved latency issues? Or have any of you been able to shoot fast action scenes without problem?

Thanks!!!
Latency depends a lot on the device you are streaming the video into. An iOS device with an A7 or better processor has been demonstrated to have 220-250ms latency. Connect it to an HDMI device and it is lower. The latency for me is acceptable. There was one version of the beta firmware that had about 1000ms delay and that was not good for anything. Fortunately that has been fixed almost a year ago while we were still in Beta.
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Old Jan 22, 2015, 08:12 AM
Discovery
ulkar's Avatar
Joined Apr 2012
271 Posts
I made a test yesterday with a 280ms latency out of a GH4 zenmuse into a liliput hdmi screen
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Old Jan 22, 2015, 11:25 AM
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United States, CA, Big Bear
Joined Jan 2006
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Quote:
Originally Posted by ulkar View Post
I made a test yesterday with a 280ms latency out of a GH4 zenmuse into a liliput hdmi screen
That's actually very good for a digital system. Each component in the chain will add to this, including the hdmi monitor.
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Old Jan 23, 2015, 07:41 AM
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Joined Apr 2012
271 Posts
I know, but for fast framing that's out of the question, how can paralinx provide a 1ms latency digital signal?
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Old Jan 23, 2015, 09:50 AM
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United States, CA, Big Bear
Joined Jan 2006
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Originally Posted by ulkar View Post
I know, but for fast framing that's out of the question, how can paralinx provide a 1ms latency digital signal?
I doubt it's 1ms and if that is just for the transmission not any other components in the chain. I do know they have very low latency but very low range as well. There are positives and negatives with every system.
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Old Jan 23, 2015, 10:01 AM
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Joined Apr 2012
271 Posts
What I was wondering is what induces latency in the transmission, as the output from the GH4 should be 0 latency, when it goes through analog it's still taking the signal from that port and then converted to analog, while there's no visible lag in the analog transmission
Don't get me wrong I love the lightbridge we're using it for several setups, just we can't when the framer has to be lighning fast (race cars for example)
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Old Jan 23, 2015, 10:23 AM
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blade strike's Avatar
United States, CA, Big Bear
Joined Jan 2006
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Quote:
Originally Posted by ulkar View Post
What I was wondering is what induces latency in the transmission, as the output from the GH4 should be 0 latency, when it goes through analog it's still taking the signal from that port and then converted to analog, while there's no visible lag in the analog transmission
Don't get me wrong I love the lightbridge we're using it for several setups, just we can't when the framer has to be lighning fast (race cars for example)
The output from the gh4 has latency as well. Like I said no digital system has 0 latency. The Gh4 still has latency through it's output, I would guess somewhere in the 20-40ms range. Then add the conversion board, probably another 10-20ms. Still very little and would bet a human wouldn't even notice it unless looking for it. But as you can see each digital component creates latency in the chain, even your LCD will add some.
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Old Jan 26, 2015, 02:08 PM
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United Arab Emirates, Dubai
Joined Sep 2006
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Quote:
Originally Posted by ulkar View Post
I know, but for fast framing that's out of the question, how can paralinx provide a 1ms latency digital signal?
1ms is the latency ADDED by the Paralinx "component" to the whole transmission chain. They achieve it by keeping the video uncompressed, which means high bandwidth and is why range is much shorter.

The added latency for the Lightbridge is about 100ms, so by using a Paralinx unit you'd only shave that much off the total latency. Most cameras with an HDMI output have more than 100ms latency of their own, some up to 200ms.
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