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FPV Indoors and Ground problems / solutions?

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I'm running a sound installation using RC cars run from FPV perspective see

http://dualplover.com/vinylrally/

i'm a sound artist and have only been using RC and FPV equipment for a short time and am having trouble getting a good picture.

basically the images are flickering alot and i get occasion drop out which the large screen monitors i use don't like, see the video on vimeo below from my last installation in frankfurt.

https://vimeo.com/45382669

i have been using the following gear for FPV

Tx

http://www.iftrontech.com/product_info.php?cPath=46&products_id=128

Rx

http://www.iftrontech.com/product_info.php?cPath=48&products_id=112

the Tx has the following attenna

http://www.iftrontech.com/product_info.php?cPath=39_68&products_id=180

and the Rx two of these

http://www.iftrontech.com/product_info.php?cPath=39_68&products_id=122

the installation is typically housed indoors originally i had these antenna

http://www.iftrontech.com/product_info.php?cPath=39_68&products_id=121

on both my Tx and Rx but upgraded to the above hoping to fix my problem but it still persists.

the Tx are mounted on thie sides on the cars see (orange led shows position of transmitter)

429949_341841285868342_1514765831_n.jpg

the cars are placed indoors in a track made form beercrates and timber here is the layout of the last track made

575139_406271779425292_1813116209_n.jpg

the Rx were mounted onto of the wall in the upper right mid section of the track (start of upper level) basically on the other side of the two crates sticking out behind the consoles

554857_408936305825506_2121299235_n.jpg

here is a short video of the Rx (posted to show iftron another problem i'm having with one unit which keeps switching off, but thats another story)

http://www.youtube.com/watch?v=GsImf911I6c&feature=g-upl

i have plenty of other photos showing various set ups and room if that helps

http://www.facebook.com/vinylrally/photos

now from reading some of these pages and other places i'm told its not the gear its the antenna!

even so i need to solve the problems i'm having so would like advice on antenna placement, possible alternative antennas, or a complete new set up.

one vendor is trying to sell me a digital set up for US$10k saying that only digital equipment will fix the problems caused by 'Ground Plane Effect & Multipathing' however this digital gear uses compression formats which have inherit latency issues of about a 1/4 second which when racing around the track will make driving at speed difficult.

what i need is a system that

dose audio and video

has no or little latency

has a small mountable Tx

works well with surface applications and indoors

any thoughts appreciated

lucas

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Cool FPV application. As you have discovered, your environment creates huge RF challenges. It will never be perfect, but you should be able to substantially reduce the image problems.

1. All of your antennas are linear polarized, which are not a good choice for your application. I suggest you change your antennas to circular polarization. Do a search on 5.8GHz Skew Planar Wheel (SPW) and Cloverleaf antennas. A popular FPV antenna brand name is Bluebeam (these are made by a hobbyist that sells to the FPV community). Also, you should try mixing a circular polarized Patch with one of these on the diversity receiver.

2. Experiment with Rx antenna placement. Sticking them on the backside of the video monitors so low to the ground may not be the best place. For example, higher above the track may work better. The ideal spot would be a location that has the least obstructions to all areas of the track. Perform careful antenna position tests at different track locations, elevations, and orientations. Keep in mind that the people in the pits and grandstands will be moving around and they too will affect the reception as their movements affect the RF environment.

3. If the Rx antennas need to be moved then move the Rx with them. Do NOT use coax extensions and avoid antennas the have long coax cables. My personal rule of thumb is avoid all coax, but when that is not possible then keep it under 6cm long when using 5.8GHz. The coax must be rated for 5.8GHz (for example RG402).

4. Experiment with different monitors. The monitor you are using seems to exaggerate the video loss due to the extended time it needs to re-sync with each video loss event.

5. It is hard to tell for sure, but there seems to be some intermittent video noise in the image that is cause by "dirty" Tx/Camera voltage or a nearby competing RF device.This is noted by the corrupted vertical sync that causes the horizontal band in the image as you drive around. After you make your antenna improvements you may need to do more investigation to determine the source of this.

BTW, your itemized component list and links were very thorough and a good example of how to post for help!

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Almost certainly the majority of your problems are antenna polarisation and probably your screen not liking video loos and 'blacking out'.

Here is a good video that enables you to 'see' the problems with antenna polarisation

A good manufacturer in Europe is circular-wireless

http://www.circular-...ar-wheel/spw58/

HTH and please let us know how you get on.

Nigel.

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after watching this video

http://vimeo.com/17959822

im pretty much sold on going digital, only one problem LATENCY!!!!

i'm almost going to buy this

WVC-SD Mini TX Digital COFDM System

http://wirelessvideocameras.com/images/wvc-sd_cofdm_digital_video_link.pdf

i can deal with <100ms latency, but discovered that the JPEG2000 compression dose not alllow for audio and must get a H@^$ system with <200ms latency.

which judging by frames is about two car lengths at speed.

question for me now is do i invest further in my 5.8 analog system and buy circular antenna.

go dual system with the above digital transmission for video and existing for audio.

with the prices involved i think i should at least try antenna first as i'm guessing zero to negligent digital transmissions must just be around the corner, dose anyone know of any systems available, being released or under development?

oh and one other question in regards to the antenna placement, you say do not have coaxial length so move the Rx, as this my might be as practical as to were i place the consoles is it ok to run lengths of the output video cable to the monitors?

also about the monitors is their a clear definition of what the monitors are doing when they reset after video loss, as a mere split second loss can mean a second or two of blank screen. i understand why this happens but i don't know what its called and how to determine whether or not a television possesses such a system or not. i ask as i don't own the TeeVees they are hired from place to place as i travel the work and i need to explain this is my technical requirements document in order for my hosts to find the right monitors.

thanks in advance

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5. It is hard to tell for sure, but there seems to be some intermittent video noise in the image that is cause by "dirty" Tx/Camera voltage or a nearby competing RF device.This is noted by the corrupted vertical sync that causes the horizontal band in the image as you drive around. After you make your antenna improvements you may need to do more investigation to determine the source of this.

oh and the cameras, they are powered by the transmitters using a cable that comes with the unit like this

Dsc05458 P&P Cable 800 x 600.jpg

using a just plug i power them up with 3c 11.1 v lipos, i'm unsure what power it feeds the camera but they are made by the same people.

im using

http://www.iftrontech.com/product_info.php?cPath=28&products_id=164

these items are all meant to be integrated flawlessly so i hope im not getting 'dity' power?

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in regards to the antenna placement, you say do not have coaxial length so move the Rx, as this my might be as practical as to were i place the consoles is it ok to run lengths of the output video cable to the monitors?

Extending the A/V and power cables is not a problem and should be easy to do in your small indoor installation.

also about the monitors is their a clear definition of what the monitors are doing when they reset after video loss, as a mere split second loss can mean a second or two of blank screen. i understand why this happens but i don't know what its called and how to determine whether or not a television possesses such a system or not.

This is an artifact of the monitor's Blue-screen feature. I've never seen a monitor manufacturer provide a specification for the sync recovery time. Unfortunately you have to test and compare on your own. BTW, on some monitors you can disable the blue-screen feature (menu setting), but this is a very rare thing to find.

If changing the monitor is a hardship then there are alternate solutions, as follows:

1. If the monitor has VGA input, then try a composite-to-VGA adapter. Some (not all) do a very good job of minimizing the sync recovery time. However, it is still a test and compare experience.

2. If the monitor has a analog/ATSC TV tuner, then try a composite video RF adapter (a small box often used to connect video games to a TV set via the antenna input). On many TV monitors this trick will disable the bluescreen feature.

Keep in mind that unless you have good antennas, digital video link solutions may suffer too. Instead of the of the nuisance of video noise and blackouts, you may instead see intermittent freeze frame images, blocky compression artifacts, and/or slow frame-rates. So if you work on improving your analog RF link by investing on better 5.8GHz antennas there is a chance you can use them on a future upgrade to a 5.8GHz digital video link.

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ok im at the point were i'll experiment with the circular pattern antenna and see how that goes before committing to an expensive digital system.

what i need now is some advice on which to choose, so far you have recommended.

bluebeam

they seam to have two choices whip or omni

i think i like the look of the omni

DSCN2434.JPG

bluebeam_reject.jpg

as more compact and less chance of it sticking out and being bent over in a crash

the skew-planar wheel antenna looks fun

spw15.jpg

but looks fragile for TX purposes which makes me ask

do i need to put a circular antenna on my car or just the receiver?

the circular wiseless range again looks good

http://www.circular-wireless.com/products-page/

any opinions on choice appreciated please back up your choices with thoughts on why these would work better within my given situation, also as stated above do i need circular polarisation on both Tx and Rx. and at the diversity side of things should i just have one circular polarised antenna on and use an alternative on the other side or use two circular anttena.

i guess all up if i used circular polarisation on everything i'll need six antenna, two for the Tx onboard and 4 for my diversity receivers so combo wise what works best with what especially at ground level and indoors.

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Personally, the Skew-Planar for ALL antennas (this way you could have a spare or 2 in case of damage).

I already linked to probably the best in Europe

http://www.circular-...ar-wheel/spw58/

If you arranged your diversity Rx's at either end of the track/circuit, you will have the best coverage.

You can also use the Rx 'upside down' so that the antenna is looking down at the track. Doing this will elimintate the Rx from actually blocking the signal.

5.8GHz was almost unusable and written off as useless for FPV just a couple of years ago due to multipathing.

It was the quest for better signal quality that drove us to find a better antenna and Circular Polarisation was it's saviour.

With the investement you currently have in your setup, what is 6 x 35 Euros going to add to it in terms of percentage?

Really, going from linear polarised to circular polarised antannas is like the difference between night and day.

Do you have 2 cars on track at the same time and both using 5.8GHz?

If so, opposite hand circular polarisation and different transmission channels will help immensely.

Choose Right Hand C-P for one setup and Left Hand C-P for the other (another good reason for converting to Circular-Polarisation).

If you contact Circular-Wireless, they will custom make you such a set of antennas.

https://www.circular...ss.com/contact/

Nigel.

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I stumbled upon an update to this FPV project in another forum. The final results were very good considering the tough indoor environment:

http://fpvlab.com/forums/showthread.php?12514-Circular-Wireless-Case-Study-2-The-Vinyl-Rally

It's too bad that OP's don't always come back to tell us how their projects turned out. There's a lot to be learned from the feedback.

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Yes it looked like a record breaking run......

Seriously though lack of feed back of the final outcome is the biggest problem on all forums. It was brought up the other day on a camper van forum I use and it has been even more of a problem when trying to find fixes for pc problems. So often you find link after link of guys that have had the same problem but not one of them bothers to post the fix when they find it.

I guess we have all done it at times as the urgency fades when you have fixed it, I do try and thank people if they help me out though.

Terry

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