What's the best VTX/RX for the UK?

[PropsToYou]

With the legal limitations on TX/RX usage in the UK, is there any hope to get decent video feed?
I';ve used Fatshark and immersion setups (I know they';re basically the same thing though), and they are ok, but by the time I';m maybe 150m away in any direction I start to get static patches. If I fly behind a tree that';s just 20 meters from me I';ll close to lose the signal for a split second.

Of course there';s always going to be a little interference when there are physical objects blocking the signal, but when I see videos of people speed flying through forests or abandoned buildings it does make me question if I';d be able to achieve even half of what they do without loosing visual?

[Paul01]

What ariels are you using?

Check the video out below, its all about whats possible with 25mw 5.8ghz

http://youtu.be/hKWll526BbU

[PropsToYou]

What ariels are you using?

I';ve got a 5.8GHz cloverleaf (http://linkowl.net/bbf6) on my quad and my FatSharks are using the FatShark/Immersion Spironet Skew Planar (http://linkowl.net/7967).
Both RHCP.

The video was interesting, but I';m not entirely sure where it leaves me.
As I';m not always flying from a corner, I ideally need to use omni';s which don';t give me a huge amount of choice. The guy in the video mentioned Airblades (http://linkowl.net/9e20) but despite being 4 times the price, would they really be any better than what I';m using now?

An alternative (though not cheap) would be I suppose to use a diversity receiver, but is there any way to connect a diversity receiver to fatshark goggles?

Thanks for your help by the way!

[Paul01]

I think you can with some of the FatShark goggles, which model have you got. Looking at Youtube people like Boris B and Juz don';t use the fatshark antennas.

Gave makes nice antennas, not sure how much of an improvement of the fatshark ones, the other option is to use higher mW TX like most others do, or get a tracking antenna mount

[PropsToYou]

I think you can with some of the FatShark goggles, which model have you got. Looking at Youtube people like Boris B and Juz don';t use the fatshark antennas.

Gave makes nice antennas, not sure how much of an improvement of the fatshark ones, the other option is to use higher mW TX like most others do, or get a tracking antenna mount

I';ve got the Predator V2s. They';ve only got one antenna port themselves but not sure if it';s possible to input an external source like a diversity box.
Hmm, interesting, perhaps when I';m feeling a little more flush I';ll invest in some alternative antennas.

With regards to getting a higher mW TX, obviously anything higher is technically illegal, however, is this really moderated or is it more just an issue if you';re stupid with it?

[Paul01]

If your away from people and not being stupid I sure you';ll never get bothered.

according to specs they have a 3.5mm av in/out port, if true you could plug a diversity vrx into them

[annikk.exe]

With regards to getting a higher mW TX, obviously anything higher is technically illegal, however, is this really moderated or is it more just an issue if you';re stupid with it?

I asked this same question during a live chat with an online store that sells multirotor parts.  The guy said that basically 25mw is the legal limit, but units greater than 25mw are widely available and used by nearly everyone, and... er... it';s a bit of a grey area. :>

[Ynot6]

you could try a TBS mini patch, then track with your head. they have a generous 90 degrees arc of pickup, so you don';t need to be spot on.

[PropsToYou]

I asked this same question during a live chat with an online store that sells multirotor parts.  The guy said that basically 25mw is the legal limit, but units greater than 25mw are widely available and used by nearly everyone, and... er... it';s a bit of a grey area. :>

Glad to hear it. So is the difference between the 25';s and the 200';s massive or is it worth the full hog of the 600mWs?

[nub]

there';s quite a difference between the 25 and 200 but not so much between the 200 and 600, in theory of course.

i';d probably go for the higher rated VTx personally.

[dirtyharry]

antennas  is everything .The formula for tx power  is a square type thingy so to double your range you need 4 times the power,but you can get 4 x your existing range by better /directinonal antennas.

I';m not an expert on these things but my system went from barely 200m range to over a 1600m by changing the antennas and separating the gps/receiver /electrics to give the best possible system.

Have a google of helical and directional antennas and you will see what folk are getting on 25mw ( over a mile is common)

[PropsToYou]

antennas  is everything .The formula for tx power  is a square type thingy so to double your range you need 4 times the power,but you can get 4 x your existing range by better /directinonal antennas.

I';m not an expert on these things but my system went from barely 200m range to over a 1600m by changing the antennas and separating the gps/receiver /electrics to give the best possible system.

Have a google of helical and directional antennas and you will see what folk are getting on 25mw ( over a mile is common)

I';m guessing you mean something like this: http://linkowl.net/c37a?
Unfortunately I don';t think my fatsharks (Predator V2) can take an external diversity box so this would require me upgrading my goggles at a considerable cost :/ It';s definitely the preferable option however.

[dirtyharry]

you don';t need diversity unless you fly behind yourself, its a bit of a leftover from ground station days, but as most folk use goggles with integrated receivers now its not really required.

Make yourself a 4 turn helical and turn your head if the signal drops.

[dirtyharry]

http://www.multi-rotor.co.uk/index.php?action=post;quote=97389;topic=11459.0;last_msg=97421

[annikk.exe]

Glad to hear it. So is the difference between the 25';s and the 200';s massive or is it worth the full hog of the 600mWs?

As others have said, the antenna makes the biggest difference.

With the power vs range thing, say if you have a 10mw transmitter and want to double your range, you would need to go to 40mw.  If you want to double it again, 160mw, and so on.
So 600mw is just over 3 times as much range as 25mw.  In theory.

Personally, I went for the VTX that weighed the least.  That';s because TWR is of paramount importance to me.  With a good antenna, it works perfectly fine for the type of flying I';m doing. :>

[bazzerh]

i';v found a good way to better signal ( or the reverse) is to use a clean and filtered power supply to a vtx thats sat away from other bits and is connected straight to your antenna, ie not using bulkheads or god forbid polarity invertors. A friend of mine had an absolutely shocking range on his vtx and i had a look, he was using a pigtail to a bulkhead connector set up, which a lot of people use but will knock down your range a bit......but it was all the wrong connector type so he had a sma to rp-sma polarity invertor from vtx to pigtail AND the same again between his bulkhead to his antenna. he even had a polarity invertor on his goggles 

[kilby]

We used to assume a 3db loss for every connector although it doesn';t sound like much its a lot

[bazzerh]

We used to assume a 3db loss for every connector although it doesn';t sound like much its a lot

he';d have been about 6 db in the red i think! hes changed it around now, vtx->antenna, and done, getting loads more good signal now

[PropsToYou]

I';ve got the VTX system on my 250 powered via the balance lead on the same battery that';s powering the quad itself, think this could be an issue?

[bazzerh]

I';ve got the VTX system on my 250 powered via the balance lead on the same battery that';s powering the quad itself, think this could be an issue?

not necessarily, an LC filter is always nice but unless you';re getting motor noise ie horizontal lines when you spool up then you can do without probably. on my latest build i went for no filtering and on 3s its marginal, i cant see anything in goggles but if i use a dvr and look back on my tv then i can see faint noise. on 4S the noise is noticable on goggles, especially on take off, but then seems to smooth out in flight. i added a ferrite ring on the +v for fpv gear and it solved it. a full lc filter would have been better but i was too lazy to make one. i think theres a fair bit of difference in vtx and cams as to how they react to slight signal noise from using unfiltered power too. tried an eachine combo with 3S unfiltered and it was very noisy. going to try a metal shielded runcam SKY with eachine vtx tomorrow to see if that helps. will report back.

[PropsToYou]

not necessarily, an LC filter is always nice but unless you';re getting motor noise ie horizontal lines when you spool up then you can do without probably. on my latest build i went for no filtering and on 3s its marginal, i cant see anything in goggles but if i use a dvr and look back on my tv then i can see faint noise. on 4S the noise is noticable on goggles, especially on take off, but then seems to smooth out in flight. i added a ferrite ring on the +v for fpv gear and it solved it. a full lc filter would have been better but i was too lazy to make one. i think theres a fair bit of difference in vtx and cams as to how they react to slight signal noise from using unfiltered power too. tried an eachine combo with 3S unfiltered and it was very noisy. going to try a metal shielded runcam SKY with eachine vtx tomorrow to see if that helps. will report back.

I';d be interested to hear how that goes. I';m only running in 3s'; so from what you';re saying should hopefully be less problematic.
Just need to decide which way to spend my money first. Antenna or TX :p

[annikk.exe]

ie not using bulkheads or god forbid polarity invertors. A friend of mine had an absolutely shocking range on his vtx and i had a look, he was using a pigtail to a bulkhead connector set up, which a lot of people use but will knock down your range a bit......but it was all the wrong connector type so he had a sma to rp-sma polarity invertor from vtx to pigtail AND the same again between his bulkhead to his antenna. he even had a polarity invertor on his goggles  :rofl:

What';s a polarity inverter? :>  And why would it affect VTX signal?

[Paul01]

It';s the adapters used to change connections from RP SMA to SMA or vise versa.

[Hands0n]

What';s a polarity inverter? :>  And why would it affect VTX signal?

I think he';s talking about those SMA adapters that allow fitting of RP-SMA to SMA(there';s four possible fitments iirc). 

Every mechanical connection is a point of signal loss. How much depends on the quality of the connector. All sorts of numbers are bandied about, but without measuring the specific setup it is difficult to judge. Generally, limit the number of connections as much as you can. The most ideal install is with the antenna fitted to the SMA connector on the VTX itself.  Pigtails are convenient for some builds but add at least one additional connection (attenuation) point. 

[annikk.exe]

Oki thanks guys. :>

[annikk.exe]

Since we';re on the subject, is the same true for the RX end?
If I use a bunch of extra mechanical connectors to connect my antenna to my video goggles, do I lose reception there too?  Or is it only on the transmitting end?

[Hands0n]

Yeah, losses occur at both ends. If you have a good antenna it may not be too significant.

Sent from my HTC One_M8 using Tapatalk

[bazzerh]

might depend on the quality of the adaptors too, if you pay peanuts then you can';t expect minimal loss. also i read recently tighten them up as much as you can, by hand doesnt cut it, they need to be really tight to get the most signal through. not ideal for goggles though so maybe just get the right antenna to fit straight on is a better bet

[davethepitch]

We used to assume a 3db loss for every connector although it doesn';t sound like much its a lot

I would not be happy with a 3db loss on my radio equipment as it could be as much as half the power lost.

Dave

[kilby]

Nobody should be, but due to varying tolerances between manufacturers (how often have you bought a standard part that didn';t quite fit) we went with that assumption.

That way you where unlikely to even consider having any sort of connector.

Same for cast 5 cables, you can imagine my horror when I found a 100 cable run with 5 inline connectors (in my current employers data centre) sure enough those stupid connectors came out at almost 4db each

No wonder the inter cabinet link wasn';t happy