Pulling my hair out trying to work out legal FPV!

Roundozo · December 01, 2015, 01:43:05 PM

Hi all,

So I'm about to get my first racing quad and deciding on the equipment to for FPV seems a mine field. So the craft itself will fly via 2.4Ghz and the FPV gear will be on 5.8Ghz. I've been looking at getting 400mw for this but looking on the internet about UK legality it would seem that only 25mw is allowed? I have some questions that I hope you can help answer for me.

I plan on flying my quad freestyle for fun/practice and also race it when possible. I've heard race meets might move to 25mw so getting this would mean I don't need to change it however when I'm playing, will this band be powerful enough for flying through the trees etc? Is the 400mw I was looking at illegal as I don't want to risk damaging the sport however if it's not then surely this will give a better image?

I'm really struggling to work out what is and isn't illegal because as usual the internet throws up many answers. So it therefore thought, who better to ask than the internet! Oh the irony! ;D

HELP! (?) (?)

marcin · December 01, 2015, 01:47:33 PM

25mW 5.8Ghz is legal in UK.

rob.thomson · December 01, 2015, 01:52:01 PM

Nothing wrong with your setup of 5.8 and 2.4.

25mw will be OK for short range. Say..
200 to 300m with no obstruction.

To go further on 25mw you need a tracker and directional antenna. Skyscraper has achieve over 1km with this setup.

I would suggest that you get a variable output vtx. HK sell some that you can swap from 25mw through to 400 or so.

This will enable you to fly legal - but upgrade if you feel it is not working out for you.

IMHO you will probably end up running on around 200mw as a good compromise.

Billy_boy_2010 · December 01, 2015, 01:52:27 PM

Everyone flies 200-600mW I wouldn't worry aabout it.

You can fly with less and a strong receiver antenna but to begin with you will find a higher wattage tx more forgiving.

Most people use the immersion rc ones.

stevec · December 01, 2015, 01:54:05 PM

As Marcin posted 25mw or less is all you have if you want to stay the right side of the law.

Many people fly with higher power than this, but it seems for the race meets 25mw actually works a bit better because there is less cross band interference.

If you are not going far then 25mw is ok. if you plan on going a long way off then you'll probably want a bigger quad too.

there was a lot of confusion around this because the law is different in America. levels above 25mw are legal there if you have a ham license, however there is no such allowance in the UK, Ham license does not allow you to transmit from an airborne vehicle so you are still stuck on 25mw.

the secret with 25mw is decent antennas. a couple of 3 turn helicals and a decent skew on a diversity rx will give you a good picture as long as you stay out in front and don't venture off the sides too much.

/Steve

iPeel · December 01, 2015, 02:00:08 PM

A 25mw VTX is the "close enough" legal choice. To be 100% to the regulation is a little more complicated as the allowance is actually 25mw Effective Isotropic Radiated Power, which means you have to offset the dbi value of whatever antenna you are using against the output power of the transmitter. This is to stop people using transmitters with highly directional antennas to increase the penetration in a specific direction, it's highly unlikely anyone would pull you up on this unless you were deemed to be interfering with any other equipment in the local area and Ofcom actually had the manpower to follow up on the complaint.

Roundozo · December 01, 2015, 02:03:14 PM

Thanks for the comments people..

I think i'll stick with 25mw then as its a 250 quad so i don't exactly plan on epic journeys etc. more close quarter flying etc. I can try and improve the signal with better antenna and it'll mean for race meets I'm setup.

...............however.......I may keep in the back of my mind one of those variable jobbies. If i'm not happy with the 25mw i'll try one of those.

Do you think 25mw will be ok in the trees as long as i have good antenna and with the quad in front of me?

Basically i live in the middle of nowhere with some lovely empty forests that i plan on exploring. I want to be able to fly around the trees not only for fun but for race practice.

stevec · December 01, 2015, 02:07:16 PM

you would be pushing your luck with anything other than flying past a tree trunk. if you fly out and the tree is between you and the quad then say goodbye to the video.

Put an RC operated buzzer on it!

/Steve

AdamG · December 01, 2015, 02:14:12 PM

Sounds like you really want to use 25mw. Give it a go, when you get fed up of all the video break up then you can buy a new higher powered vtx knowing that at least you tried :P

English Turbines · December 01, 2015, 02:23:00 PM

I have flown my Immersion 25mw vtx approx 800 mtrs away....No problems....Thats on a plane though using a Rubber Duck on the vtx and a Patch on the Monitor. Since the Monitor has rssi % on Video signal, I can see how good it is.
Using a skew on a Multi would be a different story though.....5.8G is very vulnerable to leaves and trees, it wreaks havoc with the signal, skew or no skew....:(

:vulture:

Ratty · December 01, 2015, 02:47:20 PM

What receiver do you have?

That is more important. ;D

Roundozo · December 01, 2015, 03:05:13 PM

Quote from: Ratty on December 01, 2015, 02:47:20 PM
What receiver do you have?

That is more important. ;D

Nothing yet. Looking at getting some fat shark goggles so any receiver that works really.

Ratty · December 01, 2015, 03:23:34 PM

This VTx:

http://www.supremefpv.com/index.php?route=product/product&product_id=265

This VRx:

http://www.hobbyking.com/hobbyking/store/__83195__Fat_Shark_Raceband_5_8GHz_Module.html

Some decent CP antennas, and you are all set to go.

That will be fine for whizzing around close to yourself with a few minor obstacles. Where you position yourself in the flying site is key, you want to be able to see as much as you can.

If you find it not good enough get a 200mw VTx.

(I know they are out of stock, but if you search you will find them somewhere)

BlueFlyer · December 01, 2015, 10:11:52 PM

If a FPV racing series states your equipment must be legal, then 25mw is your limit... however for personal use it's a whole different kettle of fish IMO...

There's no point in suggesting a 200mw over a 600mw... over 25mw is illegal, so you might as well get a reliable 600mw transmitter if you ever decide to venture into the world of illegal FPV and want to fly further than a gnats pube length away without using a £300+ diversity and antenna tracking system ;)

p.s. if you've ever broken the speed limit you've already committed a crime exponentially worse than using an over powered VTX for FPV... #justsaying #putthingsintoperspective

Ratty · December 01, 2015, 10:36:06 PM

There is a perfectly good reason to suggest 200mw over 600mw.

If you fly with other racers, you will swamp everyone else if you are using 600mw and you will get less pilots in the air at once.

The VTx I linked do a 25mw and a 200mw version so swapping them over is very easy if you just want to use 25mw for official or indoor races, then swap to 200mw for flying with friends ect.