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ma_meister

Wireless Lan Cameras: Weight Size Usability

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Hello

I am new to the forum. Let me introduce myself:This is my camera/video-story so far:

My plane is a wing dragon sportster (name is leo). I am using a Mustek GSmart 3 (internal 16 Meg of RAM, internal Batteries, can record 320*240 video at 10 fps for 3,5 minutes) and recently purchased a cheap (120 dollars) 2,4GHz system (1/3 [edited: not ccd but] cmos cam, 9V batterie charged, svideo to USB MPEG1/2/4 hardware grabber). I have a problem with the antenna and a lot of redish blur at the lower edge of the video. Maybe it is the automatic len aperture doing something wrong. Furthermore I will need a better receiver antenna (probably Yagi for a second person to track it). Dropouts everythere.

If you are interested please check out my page, comments very welcome:

http://www9.informatik.uni-erlangen.de/Per...ter/leopold/leo

(The text is in german). Please do not watch the last two videos if you are epileptic or have a strong sensitivity to flashing red lights. I would very much appreciate any comments on the last two videos (the 2,4 GHZ ones) and how I can increase the picture quality!

------------------

Now here is my question (Sorry, if I have overlooked any posts that deal with it already):

I am quite disappointed by the quality of analog video over the (very crowded in Germany) 2,4 GHz Band. I am thinking of trying out digital. This is my plan:

Wireless LAN (WLAN) Camera are on the market from about 100 dollars/euros up, featuring at least the same picture quality as the cheap 2,4GHz systems.

Any experiences? Are they too bulky/heavy for an electric park flyer (my plane is 600 gramm but I have no problems taking about 80 gramm extra in the air)? Power consumption could be high (they have internal webservers and all the stuff...) and sometimes live on voltages of 6 Volts.

My questions:

What happens if you lose signal? Are there any cameras doing the full NTSC (640x480) with 30 fps or likewise PAL (720x576) with 25 fps at decent codecs (MPEG4)? Do the fields choke the MPEG4 compression scheme? Are there videos online so I can have a look before buying? I would need to get a directional WLAN antenna (say 100 dollars), WLAN Camera (say 200 dollars) and a WLAN cards for my laptop (100 dollars) so I guess it is an investment of about 400 dollars or approx 350 euros.

Any ideas? Experiments already? Thanks very much!

Martin M.

Edited by ma_meister

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I'm unable to view any of the videos with Windows Media Player. The required Codec is unavailable. Can you post a link to a standard mpeg or wmf formatted video?

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Well that's pretty simple, your cam is a CMOS and not a CCD. Dark picture and red glare are typical to CMOS. You won't be able to hope for much better unless you change the camera.

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Videos in the website: The videos are Divx4-encoded. You can get the codec for free from the internet (install divx5 free edition, I think, it will play the dixv4 ones).

CCD vs CMOS: Ok, I see. If that is a typical problem then it seems I would have to switch to ccd. What I still ask myself is: are all artefacts seen in this video due to the camera? That does not seem plausible to me, I think the radio connection my ba a bit faulty, too.

But back to topic:

Are WLan cameras in use by the RC cam experts in this forum? I have checked out a lot of manufacturers and just found one that does NTSC resolution (640x480) at 30 fps over 802.11g WLan. It is called "CAS 700W". Unfortunately the data sheet does not tell the weight of that thing, which would be of paramount importance.

Regards, Martin

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Are WLan cameras in use by the RC cam experts in this forum?

I have yet to see any real evidence of that from any aerial hobby user, here or elsewhere. The robotics guys are into it, so you should be able to find examples on the net. To date, I am not impressed with the realtime video from a WLAN video source.

If you are indeed using a CMOS camera, and are using the poor results as a reason to switch to a digital video solution, then that is sort of like killing flies with dynamite. Have you seen sample videos from a quality wireless video solution? Such as what is seen on Kilrah's or yb2normal's site?

BTW, this morning I installed the latest Divx codec version on my new XP system in order to see your problem. Still does not work -- video starts, then immediately ends and Mediaplayer 10 closes by itself. I've never had great luck the Divx codecs or their proprietary player.

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video starts, then immediately ends and Mediaplayer 10 closes by itself.

Did the same to me. Crashed VirtualDub as well. Download the VLC player from http://www.videolan.org/vlc/

That's the best solution for strange formats / damaged videos.

For sure the camera is not the only problem source. It's responsible for the bad image quality, but the dropouts are due to the RF link. What does your receiver look like?

Edited by Kilrah

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Hi,

sorry for the problems with the videos, they play fine with me (all players, I must have used a really wierd codec).

Picture of my receiver unit

Martin

receiverunit.jpg

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Okay, never used this one. But at least it seems to have fixed channels which is good.

Anyways the dropouts are not too bad. You could use a better antenna to get some improvement.

Also, always think about deactivating all WLAN and bluetooth devices you might have with you (PC, mobile phone,..) as even if they are not connected they will create interference as soon as they are powered on.

Edited by Kilrah

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Hi,

I will try again with my a reflector for the receiver and sender antenna and will post results. Kilrah, you were right. We accidentally had mobile phones on. :)

cheers,

Martin

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Just to be more precise, it's not the GSM part that will cause problem, so the phone can stay on. But WLAN and bluetooth operate in the 2.4GHz band and on spread spectrum. That kills :(

Once you've forgotten and seen the result it's pretty easy to be reminded. Both devices produce horizontal lines on the image and cracks on the audio. Now I realise pretty quickly if I've forgotten to turn off WLAN on my laptop when I go flying.

Here's an example... that was my phone's bluetooth I forgot to turn off. Plus as my pocket was a bit tight I threw the phone somewhere and it ended next to the RX antenna. Amazingly I flew for around 20 mins, then my friend took over and flew for 5 more... and none of us noticed anything at the time. Only when I played the tape back I realised after a few seconds that there were repeating lines... And once more, of course that happened on a very nice flight... :angry:

http://www.rc-tech.ch/videos/TX50...010505_1100.avi (45Mb)

Right-click and save as, as it's still an old DivX video. It plays well in windows media player though ;)

EDIT: Updated link.

Edited by Kilrah

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Wow, what a great video! Thanks for posting the link (by the way I checked out your site, amazing stuff, Thanks for putting that online! Very inspirational!).

The stripes are annoying that's right. Although it does not seem as bad as the artefacts I have seen in my first flight. Will post results of my next experiments.

cheers,

Martin

Another question (I am greedy I know ;) ):

My boss at work is fascinated by Quadrocopters (e.g. Draganfly). Any experiences how much they can lift? Idea is to lift up a normal camcorder (500g) and additionally the rc cam for pilot view (about 80 gramm). We need to do it via camcorder for image quality. It will be joint pattern recognition/computer graphics project (image based reconstruction and rendering). The golden rule there is: garbage in - garbage out. While this does not mean the normal rc link setup is bad it certainly means that the less quality we put in the less we get out.

Thanks for thoughts :)

Edited by ma_meister

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You might be interested by this: http://asl.epfl.ch/index.html?content=rese...ndoorFlying.php

They have an onboard Linux computer, standard R/C as well as data communication devices. They currently use a 2.4GHz camera like we do, but would like in the future to add an analog capture interface to the onboard computer and directly process the video data with it.

All the quadrirotor models I've seen are of relatively small size, that is they could lift maybe 100gr, not more... This one has been fitted with a 15gr video system (CCD camera/transmitter).

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Interesting, thank!

I think we will need to modify a draganfly or xufo for our purposes (prolong the carbon axes to the rotors, increase rotor diameter, add bigger motors, add more batteries for more voltage and mAh).

cheers,

Martin

Edited by ma_meister

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