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Old Mar 15, 2015, 08:53 AM
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FPV image quality?

First, I am new to FPV, and I have flown a plane only once. My fpv gear is still on the way from HK.
I have been searching forums, but could not find the answer I wanted. All of the content I watched on YouTube seem to show that the image quality we see through the goggles are crap. I would expect the quality to be just like what we see through the HD recordings, except downscaled, hence, like YouTube on 480p on full screen. But the recordings with the OSD overlay seem crap, blurry and like YouTube in 50p or sth. I bought a complete 900MHz kit from HK with a wide angle lense + a quanum goggle kit. do I need to change sth to get the video quality I am expecting??

I was thinking of using a strong 2.4 GHz booster with a router and stream the camera feed in HD from an android phone. The latency would be extremely low, trust me, and we could even have FPV in 4K. But would it work??
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Old Mar 15, 2015, 01:11 PM
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It is not as bad as the videos but it is not HD quality.
Do a lots more reading in these forums on the subject.

Do NOT use a 2.4GHz booster. For one it is not needed and will not improve video quality and may degrade the video. It will also cause interfere to others and maybe even your own equipment and may also be illegal in your Country.
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Old Mar 15, 2015, 01:40 PM
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If you really want an HD video link, then you have to buy one of the few very expensive systems on the market. Like DJI LIghtbridge and the Parrot Bebop

And you have to deal with their severe limitations
1/ latency. The HD image you get will be fractions of a second after the fact. Makes it impossible to fly anything that is responsive. Good for Naza multirotors
2/ limited range. These HD systems only reach out a couple hundred yards, and can have dropouts. However the Bebop with skycontroller boasts good range to 2km. BUt I have yet to see real world reviews on this system
3/ proprietary/compatibility. HD system like the Bebop only works with its own equipment. You can't modify anything at all. The DJI Lightbridge - I don't know. No OSD unless the system you buy has one, then you cannot change it
4/ heavy. Items like DJi Lightbridge are heavy compared to normal analog FPV stuff
5/ beta versions. There are a handful of other HD systems out there. Like the Skydrone and also some DIY GSM HD digital video. These are either vaporware, very much unknown, or known to operate very poorly.
6/ Wifi from cell phone or Gopro - for FPV, this does not work. period
7/ EXPENSIVE

So the conventional analog FPV systems are still the best for real FPV flying. There is no contest here.
1/ instant video. no delay
2/ CHEAP. now you can buy 200mW vTX for $20, and they work well. Same with good analog cameras, for like $30. Not a disaster if you bust something - spares are cheap
3/ CCD camera technology: no jello, and they work well in handling light. Can even fly at night with them. A lot of the bad image quality you see out there is because people bought the crappiest CMOS cam from Hobbyking or ImmersionRC. BUt $30-50 and you are golden with a good CCD cam
4/ lightweight
5/ compatibility. wide selection of goggles, LCD, DVR, OSD, receivers, you name it

Also: video will tend to always be poor in low light. Usually worst with CMOS, but like all cameras ever made going back 150 years, the best image comes in bright sunlight which we can't always have to fly in.
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Old Mar 15, 2015, 03:21 PM
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Like been said, HD or digital image is only suitable for multirotors and at close (less than 300 meters) range.

If you want a plane you are stuck using analog, as digital is impractical:
- Too expensive
- Latency
- Very limited range
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Old Mar 15, 2015, 04:29 PM
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Quote:
Originally Posted by cantremember View Post
Like been said, HD or digital image is only suitable for multirotors and at close (less than 300 meters) range.

If you want a plane you are stuck using analog, as digital is impractical:
- Too expensive
- Latency
- Very limited range
range is changing for this HD tech though.

Even some folks with LIghtbridge getting up to 3km.

Dji Phantom Lightbridge LONNG Range Test 3.3KM. (9 min 12 sec)


The Bebop claims 2km using the patch on their skycontroller. BUt from the early real world reviews of it, the range is drastically shorter - like only a couple hundred metres!
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Old Mar 15, 2015, 05:22 PM
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Question: In that video ^ why is the frame rate in the osd view different from the HD recording? Shouldn't they match?
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Old Mar 15, 2015, 05:37 PM
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guess that's how they reduce the latency and dropouts? look weird, yeah. don't put Lightbridge on your FUnjet, LOL
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Old Mar 16, 2015, 06:22 AM
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Quote:
Originally Posted by ishj View Post
First, I am new to FPV, and I have flown a plane only once. My fpv gear is still on the way from HK.
I have been searching forums, but could not find the answer I wanted. All of the content I watched on YouTube seem to show that the image quality we see through the goggles are crap. I would expect the quality to be just like what we see through the HD recordings, except downscaled, hence, like YouTube on 480p on full screen. But the recordings with the OSD overlay seem crap, blurry and like YouTube in 50p or sth. I bought a complete 900MHz kit from HK with a wide angle lense + a quanum goggle kit. do I need to change sth to get the video quality I am expecting??

I was thinking of using a strong 2.4 GHz booster with a router and stream the camera feed in HD from an android phone. The latency would be extremely low, trust me, and we could even have FPV in 4K. But would it work??
If you wanted better picture quality then you shouldn't have went with 900 lol.

Should have went this 5.8 for "better" picture quality.

I run 910 mhz for my own reasons and picture quality is not one of them lol.
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Old Mar 16, 2015, 01:18 PM
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Sorry, I did not get any email and thus thought that no one replied
For those saying that I would have issues with latency, check out stuff such as limelight. The latency is less than 50 ms in many cases. Creating a little program for android that would use a similar system to transmit even 720p at 30fps would get me a near perfect image with negligible latency. But the issue remains: even if the router is able to transmit data far enough, the phone would need to transmit info back, and since it has a tiny TX , how the hell would I boost the signal coming from the phone??

Unless I got everything wrong and Wifi does not work that way and the powerful TX only needs to be on the router I am using.
If that is the case, I will be orgering a WiFi booster ASAP ( https://store.3drobotics.com/product...plifier-1000mw )
Also, could I use 2 of those in series??



If any super intelligent person is reading this, a good idea would be to use use a high res camera and split the image into several parts, send them on separate channels to the ground using existing protocols, get them back together on the ground separately and finally, stitch them to get a good high res image. Another option would be to create a new protocol and then send alternate frames through several transmitters. If someone with a good programming knowledge is reading, contact me. You could kick start this project, and having a lot of time on my hands, I could do a LOT of the work.
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Old Mar 16, 2015, 01:19 PM
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Quote:
Originally Posted by new user View Post
If you wanted better picture quality then you shouldn't have went with 900 lol.

Should have went this 5.8 for "better" picture quality.

I run 910 mhz for my own reasons and picture quality is not one of them lol.
I thought that the frequency does not affect the image quality. Explain this to a noob plz..

thanks
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Old Mar 16, 2015, 01:26 PM
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Sony Effio-V: second test (3 min 37 sec)


Is this the quality I am expecting??
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Old Mar 16, 2015, 01:45 PM
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That is about as good as it gets in analog video. It's unlikely you'll get that good on 900Mhz.
It just doesn't have the filtering, selectivity and overall S/N ratio to get a picture that clear.
900Mhz also gets stepped on by cellular signals really hard in some locations.
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Old Mar 16, 2015, 02:22 PM
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You have some ideas but they aren't the "analog killer" because they have downsides. Wifi like you said needs to have a strong transmitter on both the aircraft and the ground, doubling the difficulty.

Wifi does use packet-based transmission, but unless you use an UDP protocol to transfer the video, it will result in "hanging" image because a packet got lost and the stream gets interrupted until the aircraft retransmits it. Packet/chunk based is handy if you have severeal streams or applications going at once, but if you only do one thing (streaming video) I don't see much benefit.

You could increase bandwidth by using several frequencies at once. But that would double/triple the amount of antenna's you need, and also half your range as high frequencies don't reach as far.

Another limit is the effort, programming your own transmission protocols and whatnot would take a lot of effort and time without any guarantee of success and basically re-inventing the wheel, digital video transmission protocols are already out there like DVB-T etc.

It's possible, it's just so much less practical to achieve on a small hobby model.
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Old Mar 16, 2015, 11:20 PM
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True, packet loss might be an issue
However, those signal breakups when using analogue, don't they have the same effect?? Also, a 2.4GHz booster smaller than a battery does not seem to be much of an issue on the plane.

As for the multiple-tx-issue, just look at the size of a 5.8 GHz transmitter! Three of these in a Bixler + a raspberry pi would not be an issue. ImmersionRC had a wide spectrum of frequency, and even 4 of them close together might just work, even with limited range. Then as a beginner project, I could try making a video splitter.

BTW, I will be using openLRS, what video frequency would be best for my current setup??
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Old Mar 17, 2015, 01:22 AM
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No, with an analog signal, you can fly through quite a lot of visible static and recovery
from momentary loss of signal is instant. With any type of decent digital video compression
you have to wait for the next key frame before picture is recovered. The higher
the level of compression the longer the interval between key frames and
that can be up to several seconds. The best digital systems need a two way link so the
Rx can transmit information back to the Tx to tell it to switch to lower resolution or
slower frame rate to handle a lower S/N ratio.

There are uncompressed HD transmitters but they use an enormous amount
of bandwidth. It's not enough to just say "I'll split up the signal and transmit over
several channels, and recombine at Rx", if you don't actually know how to split
and recombine an HD signal. None of these discussions are new here. People
have been talking about digital HD FPV for years and some have created
some implementations but I have yet to see a single one that works worth a damn for
fast proximity flying or flying under trees and such.

Most folks are content to pilot through a reliable analog signal, knowing they're
capturing a high quality HD video with an onboard camera, they can enjoy later. Why don't
you try that first, before you try to reinvent the world. There's a reason we do things
the way we do, and it's not for lack of imagination.
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