TBS Crossfire (2W) vs Dragonlink - best range and penetration

The title says it all… I want a (VERY) long range system, and I will manly be flying large fixed wings and will get FPV feed over 4G LTE.

So which system do I go for? I do plan to upgrade from stock antennas to highly directional ones. My ultimate goal is about 300-400km, LOS is not always garanteed (trees, maybe a small hill)

Latency doesn’t really matter I guess (but it shouldn’t be too large, 4G LTE is slow for my requirements.

My issue is this: I’m aware that 433mhz (dragonlink) has MUCH better range and penetration than 915mhz (crossfire) but the crossfire operates at 2W vs dragonlink at 1W

Also, are there other systems that I can take into consideration?


Wow. My first reaction, 300~400km, without LOS (even with LOS ), I don’t think it will be possible. Secondly, I don’t think this will be legal in most countries. We are using EzUHF for RC control, but never gone further than 15km or so. I wonder what application you need this for.

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By the way, there is an online calculator to estimate the range: http://www.maxmyrange.com/

If you feed this with 433Mhz, 1.5W transmitter and 2 x 1/2 wave dipole, you get about 45km.

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You are quite right… It’s no small feat :smile:
I have special permissions, but I prefer not to discuss those. But valid point indeed.

I remember I saw a video a loooooong time ago on YT of a 500km flight (it was a My Twin Dream airframe). I’m not sure of the specifics of the Tx but if he can do it, so can I😁

It should be possible with a yagi on the Tx side…

Now this will be very useful. Thanks!!

[edit] According to the calculator, the dragonlink is far superior to the crossfire (177km vs 100km, both yagi on the tx side). Intresting.

Wonder if there are any other systems out there…
Maybe I could get by using a booster?

why not 4g cellular. then you can do even greater distance

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Latency is too high for my requirements, and the coverage in my area isn’t that great.

Well, for sure you need directional antenna on the TX side. Having said that, of course you will need an antenna tracker to make sure you’re pointing at the aircraft.

A booster for sure will help, but from my experience, nothing beats good directional antenna.

On the receiver side, you need a very sensitive receiver, better than - 110db or so and if course a good, omnidirectional antenna.

Would be interesting to try to reach the maximum range.

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Hi, why not setup a relay station? would this be something to consider? It would have improved reliability due to coverage reasons.

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Oooh yes! That may have slipped my mind for a while there…! Very true. Thanks for the heads up :sweat_smile:

Very intriguing… time to do some more googling. Maybe there are other Rx s out there with this kind of sensitivity (or better)… (not just Dragonlink)

Looks like a directional Tx antenna and tracker are the way to go. As you said, I probably could get it done with some clever antenna voodoo… (150-200km is a start!)
We can see about boosters etc from there

That is definitely a great idea! I hadn’t really considered it before. My final goal is to cover an area of 420 by 200 km so this is definitely a step in the right direction. Two well powered relay stations should do it nicely.

First I will use @Verloop’s advice and squeeze every possible drop of range from a single Tx and lets build on it from there.

I just want to thank everybody who is giving me advice and it does help a great deal. Thanks guys!

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you need a relais, problem is the curvature of the earth. even if you fly very high around 150km is “reliable, in practice” the max i would say. of course you can use a high power rf system and use the bounce of in the athmosphere. but for that you need 20W+ which is not practical on the plane side.
crossfire is btw complete unprofessional, go for rfd900 talk to info@rfdesign.com.au about your needs. they can help you.

btw dragonlink is far supirior to crossfire, regarding range and noise

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Totally agree with you. In the past, I’ve been experimenting with many combinations of transmitters and receivers, but couldn’t get over 50vto 60 km. The problem is not only the curvature of the earth, with that kind of range you have to guarantee unobstructed line of sight. Even the slightest obstruction, will completely kill your signal.

So what we do now, for any mission, we only fly auto mode. We rely on the reliability of the autopilot, and when we lose telemetry signal, we are confident the UAV will return home. We made all systems redundant and high quality.

For us, this is the only way to fly long range.

Of course you could try to stretch the range, but for sure reliability will go down.

As I mentioned before, it would be interesting to know the maximum range, but bear in mind, the further you fly, the more dangerous it gets.

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Was about to say just go get a RFD900 :laughing:

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what range do you reach now? Large fixed wing? How large? The last years we flew with Scherrer TX700 (0.5-2W) and RFD868 (1W). With enough flying height its good for up to 40km. TX700 with add. 8W Booster with Yagi and antenna tracking can reach up to 120km. The RFD is too weak to reach that range.
This cofdm transmitter can reach 150km

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@InsanitySquared Well, that’s consistent with our experiences. I have 1 more question. You mentioned you needed a range of like 400km. Up and down, that’s 800 km. Flying at 80 km/h that’s 10 hours flight. Even at 100 km/h is 8 hours. And that’s only if you fly in a straight line, just up and down. Is your UAV capable of doing that?

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Right. So it seems like without relays 150km seems to be about the maximum.

That is very true. I was checking those out yesterday and they seem to be 5kg+, not at all practical. I’d rather use Irridium or something to work through satellites (speaking of which… that may not be too bad of an idea! (satellite))

I used to do that a lot :joy: oh I miss those days… See, the thing is, I’d honestly love to do that, but the issue is my mission calls for a landing at one end, and the landing area isn’t always suitable to land on, and I want to be able to fly manually in case of such a / any other emergency. This is only required until I can perfect my automatic control algorithm, which uses image processing to assert whether the landing area is safe or not.

The project is still in the planning stage and the final vehicle will be a (tilt rotor) quadplane.

Good catch. In short, not yet :sob: But keyword: yet. I’m planning on using those new solid state lithium sulfur batteries, and that should allow for the range I’m looking for. This whole project is just one big experiment :sweat_smile:

Right. So far here’s my final verdict:

I will most probably go dragonlink for now and setup relay stations as required. Then later on when I gain confidence I shall make it fully automatic, which is clearly the best way to do it.

Just for kicks, as a side project, I’ll try to get as much range as possible from a dragonlink. Any suggestions? (or shall I make that another topic)

One more thing: How much power does the dragonlink transmit at? I’m getting conflicting info from various sites. Some say the advanced slim runs at 1500mw, but the official site (store) has only one Tx listing, and that is the advanced wifi @ 1000mw:

^^Thats not the only site with the 1500mw claim

official from dragonlink site

What is the latest and greatest version of the dragonlink and where can I buy it from?

One last thing: does 1.3 / 1.2 Ghz video actually greatly interfere with GPS? (with filters)

Again, Thanks everyone. You guys truly are great!

No. I have never had any problems with that. Even without filters.

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Wow. Well, I can tell you already that that will be impossible. The moment you start your landing at such a distance, the altitude will decrease until a point where you loose connection (curvature of the earth). And believe me, that will be before you touch the ground. Unless of course, your relay station is very, very close to your landing spot.

Why not use 2 teams, one for take off, switch to auto mode, and at the landing site, team 2 takes over for landing. We’ve done that. Works perfectly.


Sorry but this sounds like you have no actuall experiance at all, and all the planning you are doing is just theoreticaly. The landing thing… that is not gonna work with whatever (point to point) system. tilt rotor vtol, 150km (300km rounttrip) solid state lithium sulfur batteries. Sounds like one of those startup guys saying blockchain digital twin and industry 4.0 in one sentence.

I would say, get a airframe, install the dragonlink, use a 5 element yagi, no tracking. 800mw 1.2g video transmitter (yes it will influence your gps, seperate them as much as possible!). And start flying. come back when there are more questions.

the dragonlink system is 1500mw but hey, the mw is not important at all, your antennas are.
contact Michael Bigelow support@fpvpro.com directly. and buy the large lr rx ! with that you can also send telemetry back.

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