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what range to expect of crossfire / dji air unit

thetechnobear

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so.. Ive just done my first flights with a traditional 5" drone, coming from the DJI FPV....
I've got a few questions, which are partly expectation.. partly 'is it right'..

Im running a 5" with a DJI Air Unit, Googles v2 , with Crossfire Micro TX v2 in Radiomaster TX16s , and Crossfire Nano RX. (stock T antennas?)
I've tried fcc/1200mW to DJI on Ch1 and I tried crossfire at 500mW (868mhz)

The thing is... Im getting about only 400m meters from this, before crossfire goes down to about LQ 1:80%
also the video seems to start breaking up pretty quickly too..

Im a bit surprised about this, given the DJI FPV (on 2.8ghz) can do a few kilometers in the same flying area....
(Id say this is worst, than im getting with the DJI FPV in CE on 5.8ghz)

also I understood even at low wattage , crossfire can do kilometers.... I know I can crank up crossfire power, but id have thought 500mW would be completely fine for 1-2km in open countryside, which is max i need.

similarly, Im a little confused whats going on with the googles/air unit
I see they are fixed to 5.8ghz, whereas i usually use 2.4 for range - but even so, given the power, it still seems low.

any thoughts?
 

tevek

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Well that doesn't seem right. I have a number of AU and vista quads including a home brew Diatone R349 that will easily get me out to 1.5 klms. I’m in Australia so running on 915 MHz and 500 mW and did the the fcc hack so the bigger quads including my 5 and 7” units are good for well past 2 klms. Probably a stupid question but did you update the FW on the nano receiver after binding it to the Tx? Maybe check you are also running the latest FW on Agent X for your transmitter module. If you are also losing video at 400 mtrs, it maybe an antenna issue with the AU, not seated correctly or the battery is blocking the antennas. I try and mount the immortal T crossfire antenna up the front of the quad so that it is facing me on the return trip, but even so my LQ rarely drops below 93 and that is usually behind buildings or trees 3-400 mtrs away. Out in the open is not an issue.
 
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Madhungarian

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I read on another thread that you bought a custom build from someone, was this quad used? Tevek is right, I fly my baby croc (caddx vista) and my Iflight XL5, easily over 1.5k no problem could go much farther , rarely do I have my LQ go below 99(which I also run 500mw on my Tango2) and my data rate in my goggles rarely goes below 50mb, I also have neighboring homes with interference. My XL5 came with a defective air unit in which the range was limited so it is possible you have a defective air unit in which it's power output has been damaged or with the antennas not being seated/connected properly like Tevek said. I bought an air unit separately and replaced it and this solved my issue after switching out the antennas had no affect.
One thing to check is 868mhz the right frequency for your location, having this set wrong can greatly reduce your range for crossfire.
 
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droneguy

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At 400m-500m it would appear there is an issue with your antenna as this is the typical range with no antenna attached. With a proper setup 500mW and an imortal-T antenna, you can easily get 10+kms which will exceed your video range by a fair margin.
 

thetechnobear

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yeah, Ive determined now there was an issue in the way the telemetry was reporting... so I was being told it was about to fail, but actually was fine - so looks like crossfire is absolutely fine.

as you say, the main issue now is the the video...
Ive a feeling this is due to the air unit only supporting 5.8ghz, which Ive noticed on the DJI FPV tends to get blocked much quicker.

today, knowing crossfire was ok - I pushed it out a bit and I noticed that I if I stayed level with my altitude, I was fine out to 800m, still 50mb, I only turned back as I realised I really should test my gps rescue ;)
however diving down into the valley, Id suddenly get some big drops (as things got in the way?!)

I've a faint recollection on 5.8ghz, the DJI FPV had similar issues ( but I've 'forgotten' as I now always use 2.4ghz) - I think I'll do a back to back test... I suspect the the results with both on 5.8ghz will be much closer.

so I think its partly, just 5.8ghz, and partly the terrain im flying...
however, I am now considering trying some iFlight Crystal HD patch antenna for flying the 5",
I think this may help here, since they are directional , and I am generally flying 'in front of me' when diving the valley.

im also not overly worried...
this 5" is for more freestyle/close proximity flying fun, so it does not need to go out that far.
at the moment, I also feel the dji fpv feels more 'reliable' for longer range stuff...
thats all ok... thats what Id planned on anyway.
 

Madhungarian

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yeah, Ive determined now there was an issue in the way the telemetry was reporting... so I was being told it was about to fail, but actually was fine - so looks like crossfire is absolutely fine.

as you say, the main issue now is the the video...
Ive a feeling this is due to the air unit only supporting 5.8ghz, which Ive noticed on the DJI FPV tends to get blocked much quicker.

today, knowing crossfire was ok - I pushed it out a bit and I noticed that I if I stayed level with my altitude, I was fine out to 800m, still 50mb, I only turned back as I realised I really should test my gps rescue ;)
however diving down into the valley, Id suddenly get some big drops (as things got in the way?!)

I've a faint recollection on 5.8ghz, the DJI FPV had similar issues ( but I've 'forgotten' as I now always use 2.4ghz) - I think I'll do a back to back test... I suspect the the results with both on 5.8ghz will be much closer.

so I think its partly, just 5.8ghz, and partly the terrain im flying...
however, I am now considering trying some iFlight Crystal HD patch antenna for flying the 5",
I think this may help here, since they are directional , and I am generally flying 'in front of me' when diving the valley.

im also not overly worried...
this 5" is for more freestyle/close proximity flying fun, so it does not need to go out that far.
at the moment, I also feel the dji fpv feels more 'reliable' for longer range stuff...
thats all ok... thats what Id planned on anyway.
If your channel is mapped to only show RSSI than yes your numbers can fluctuate from what I heard, setting it to LQ only and not both should give you the most accurate reading, according to Bardwell, and that is how I have it setup.
 

thetechnobear

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yeah, as i said , I already sorted out crossfire, once I used LQ, and also messing with some settings on the radio/understang the telemetry warnings - thats all ok now :)

But, Im still a bit disappointed with the the video range, and trying to decide if its 'normal' or not....
generally, its getting less penetration that id expect, even at 1200mW

I did quite a few test flights yesterday and today.
(stock antenna - goggles/air unit , googles v2)

at 1200mW with clear line of sight , I seemed ok to over 1k (was still getting 30mbps)
but get a few things in the way, and it drops quite quickly.

I did a baseline test - 25mW, seemed to go to around 600-700 meters, before dropping down to < 5mpbs, so turned around - and went to 1, then picked up :)
this seems a tad low, but perhaps 'in the ballpark' ?

I've also now tested my gps rescue and failsafe - so I could do a longer run at 1200mW and see what that gives me.


-------

as a comparison, I also took up the DJI FPV , forced it over to 5.8ghz, and took it on the same flight path.
wow, its was so much better...
places I was getting signal break up/focus mode kicking in on the air unit, were totally clear, not even dropping a bar. areas which were almost cutting out on the air unit, id see a one bar drop on the dji fpv, and perhaps a bit of focus mode happening.
there are just some places, that it could fly that were impossible with the air unit.

its a bit disappointing, but at the same time, gave me real admiration for whats been done on the DJI FPV - the signal is so rock solid, the camera is much better, and the flight time was fantastic :)


anyway, I think there is hope...
I just need to determine if I need better antennas, or if there is something wrong with the air unit.
I think im going to get some iflight crystal hd, and see if they help.
 
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Kilrah

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Yup it's one of those cases where "V2" brings massive improvements...
 

Madhungarian

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yeah, as i said , I already sorted out crossfire, once I used LQ, and also messing with some settings on the radio/understang the telemetry warnings - thats all ok now :)

But, Im still a bit disappointed with the the video range, and trying to decide if its 'normal' or not....
generally, its getting less penetration that id expect, even at 1200mW

I did quite a few test flights yesterday and today.
(stock antenna - goggles/air unit , googles v2)

at 1200mW with clear line of sight , I seemed ok to over 1k (was still getting 30mbps)
but get a few things in the way, and it drops quite quickly.

I did a baseline test - 25mW, seemed to go to around 600-700 meters, before dropping down to < 5mpbs, so turned around - and went to 1, then picked up :)
this seems a tad low, but perhaps 'in the ballpark' ?

I've also now tested my gps rescue and failsafe - so I could do a longer run at 1200mW and see what that gives me.


-------

as a comparison, I also took up the DJI FPV , forced it over to 5.8ghz, and took it on the same flight path.
wow, its was so much better...
places I was getting signal break up/focus mode kicking in on the air unit, were totally clear, not even dropping a bar. areas which were almost cutting out on the air unit, id see a one bar drop on the dji fpv, and perhaps a bit of focus mode happening.
there are just some places, that it could fly that were impossible with the air unit.

its a bit disappointing, but at the same time, gave me real admiration for whats been done on the DJI FPV - the signal is so rock solid, the camera is much better, and the flight time was fantastic :)


anyway, I think there is hope...
I just need to determine if I need better antennas, or if there is something wrong with the air unit.
I think im going to get some iflight crystal hd, and see if they help.
The iflight patch antennas and stubs work a bit better than stock(I use them), those however only work on 5.8ghz, unless there are new ones out that work on both 2.4ghz and 5.8, you will need to remove them and use the stock antennas if you want to fly your DJI drone on 2.4.(not convenient) I would also switch out the antennas that are on your air unit, on my baby croc lr4 I had to switch out the antenna(just one since it's caddx vista) because of a crash, and even though the original one before it broke was pretty good, the one I replaced it with was not the one it came with. I replaced it with something similar that came on the IFLIGHT chimera4 and the range was even better like 20 percent.
I do not own the DJI FPV drone but I would say yes it does have a better transmission system keep in mind it runs at 1400mw in FCC, the drone itself has 4 antennas and the trans system is newer. If the antenna replacements do not seem to help out that much, and you can afford it, try out a Iflight chimera4 or Geprc Baby croc LR4, they will fly longer than the DJI fpv drone with a li ion pack cruising around exploring. The easiest and cheapest route would be just use your DJI for long range and your 5 inch for freestyle like you said in the previous post.
 

thetechnobear

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yeah, Im aware of the duality... I see no issue switching antennas between use.
(or I might test the dji fpv fixed to 5.8ghz when using the iflights - see if thats acceptable, when I cant be bothered to switch)

also the v2 goggles are using linear antennas rather than LHCP used on the air unit, so thats also probably not helping.

I think I'll order some replacement air unit antennas and a couple of different google antennas and see if that helps.

Im not really after long range - actually Id just like a bit more penetration in the sub 1km area.
I suspect a bit of messing about will get me there :)

indeed, I plan to keep using the DJI FPV for longer range stuff, honestly, even though I have gps rescue working nicely on the 5", I trust the RTH on DJI more, and also its just a really nice 'cruiser'.

... that said, if i can get a bit happier with the DJI air unit range,
then I may build a longer range quad, I think as it can get pretty windy here, Im currently thinking I might go 6".

but thats a new topic for another day, assuming i can get the air unit to get the range I need...
but I do quite fancy the idea of building my own quad now.
 
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cootertwo

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It is amazing how much better the FPV drone is. After I got mine, I was so impressed, I bought a few Vista, and a couple Air units, to upgrade some of my older analog drones. But I was quickly disappointed in the quality, and especially the range difference. It's better than analog, but nothing like the FPV drone and the Occusync 3
 
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thetechnobear

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yeah, Ive just ordered some iFlight Crystal HD patch antennas, and also some of iFlights stubbies.

it does seem the v2 goggles are performing worst that the v1 , I think due to linear vs lhcp antennas.
(dji drone uses linear, air unit is lhcp)
Im quite interested to see if just switching to the lhcp stubbies actually helps.

I do think there is a way for this to work well, with different antennas, as some do show good range/penetration with the air unit.

perhaps, it wont ever be up to the dji fpv - but thats ok too.
Id planned the 5" for close stuff, and dji fpv for crusing/longer range anyway.

but interesting to see how the tech has evolved, and interestingly enough - in all the reviews I saw of the DJI FPV by 'traditional' fpv-ers - not one of them, mentioned how much better the dji fpv was than the air unit.

I guess, lets hope DJI one day (via caddx perhaps) make an air unit v2 with these improvements - it'd be a massive upgrade!
 

thetechnobear

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iFlight Crystal HD and iflight stubbies are here, and had my first flights with them :)

I've not done any measurements yet to compare with stock v2 antennas.
but generally they seem to be much better when there is clear line of sight, they hold on to the 50mbps link for longer.
penetration in my area, I think is a bit up n' down, I think generally they are a bit better than stock antennas.

(I'm still using stock antennas on air unit, as I couldn't find any decent LHCP mmcx antennas in my local stores )


that said, I really need to run a back to back test...
my plan is to do a test on 25mw (ce mode) with different setups, and compare results, basically on penetration and distance.

current plan is:
# v2 googles + air unit (25mw)
-- stock v2 antennas (omni)
-- 4 iflight stubby (omni)
-- iflight crystal hd + 2 i flight stubby

# v2 googles + dji drone (fixed to 5.8ghz, CE mode - so, 25mw)
-- stock v2 antennas (omni)
-- 4 iflight stubby (omni)
-- iflight crystal hd + 2 stock antenna

I'll use 50mbps mode, with focus mode on, high quality.

flight will be 1km (or drop below 5mbps!) in clear line of sight, then back, down into a valley, so start seeing penetration (thru hills, and partial hillside cover)
then back up the hill thru where trees start blocking more, but at closer range.


questions are...
main question - is it worth switching around antennas? esp, if you have a DJI drone
other questions are ... does LHCP (iflight) / Linear (stock) make a signicant difference to either air unit (lhcp) or dji drone (linear)
how much/when are directional patch antennas beneficial? (iflight crystal hd) ... given omnis are often more convenient.

im intrigued to see what the results are... as casual testing so far is honestly pretty inconclusive.

my current bet is on... seeing some improvement with the crystal hd on the air unit, and the dji drone being better on the stock antennas.
but Ive a feeling, there in the penetration tests we might not see a huge difference.

once I've done the tests, I may well so the same test but with 2.4ghz on stock antennas + dji drone - which I think (unfortunately) from experience will be much better than all of the 5.8ghz tests.







( * ) I'll use 25mW, as its easier/quicker to see signal degradation.
 

droneguy

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The iFlight Crystal HD antennas are tuned for 5.8GHz only and will provide a narrower but longer beam which will improve the range and penetration directly in front of the antennas for the air unit but will have a negative effect on range for the DJI FPV drone when it's operating in 2.4GHz since the antenna will be inefficient for that frequency. The DJI FPV drone will use both 2.4 and 5.8GHz so you would actually make the range and penetration worse for the DJI FPV. Using the DJI FPV in 2.4GHz is what provides the range you are looking for. The DJI FPV use 5.8Ghz at short range and switches to 2.4GHz at longer range.
 

thetechnobear

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Thats why I explicitly stated I’m running in 5.8ghz mode.
we all know about the 2.4/5.8 ghz duality of the FPV drone.

I also stated I know 2.4 ghz is more suited for long range, but that’s not the point - this is about why the air unit performs poorer in 5.8ghz mode than the dji FPV drone.

and again, I’ve already my theories on why, see above ... what I was after from this post, was experiences not being told what I already had stated I knew.

why is it that anytime anyone mentions the dji drone the FPV-ers assume noob ? rather than read the posts ?!

Anyway, for those interested, I completed test flights today with all combos - with some interesting results - video shortly :)
 
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Madhungarian

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I found this, was posted not too long ago, as you can see there is a hard limit on the air unit at 8.2 miles(he could have gone farther). This person is not using anything fancy. This is probably not possible with the DJI FPV drone.
 
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thetechnobear

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I found this, was posted not too long ago, as you can see there is a hard limit on the air unit at 8.2 miles(he could have gone farther). This person is not using anything fancy. This is probably not possible with the DJI FPV drone.
wow thats a nice flight... also really interesting to see the specs of the drone they used!
its impressive that the air unit (with appropriate antennas) can do this on 5.8ghz.

yeah, I'd seen the 'hard limit' on the air unit - the assumption is its a timeout on the protocol , which seem reasonable.
(since the air unit doesn't have gps, so doesn't know your distance)

the DJI FPV couldn't do this distance due to batteries - max flight distance Ive recorded is around 10.5km, Im sure this could be stretched a bit, but not to 10k out, and 10k back ;)

honestly though, I get a bit antsy, at 2.5-3km out ... I guess partly due to legal and safety concerns.
( i do live somewhere that I could get 20-30km clear line of sight - but honestly, Id be just too nervous above 4-5km)

so, Im not after long range - rather a nice stable connection out to that of distance (e.g. 2-3km radius).

increasingly, it feels like penetration is the defining factor for me,
not because Im flying into dense forests/buildings, but just because I like flying low, and at around 2-3km bits of hillside, trees start getting 'in the way' and disrupting your signal.


I did test the DJI FPV with the iFlight Crystal HD (fixed to 5.8ghz) and they seem fine, I might to a longer range test later.
but given, I can get a clean signal over 3.5km with the stock antenna (using 2.4ghz) its rather a moot point.

however, they are vital for the air unit... that is clear.
I need to get a little more comfortable with my 5", but given what Ive seen so far with the iFlight Crystal HD on the v2 goggles, it looked like they'd do 3+ km easy.
( iirc, on my test, I still had 50.4 mbps at 1km, using 25mW !!).


the dji fpv in my location is still a bit more versatile/reliable - but overall, Im now happy with the air unit using my antenna and crossfire.

it'd be lovely if DJI update the air unit, to incorporate what they have learnt from the DJI FPV Drone - and in particular add 2.5ghz support.
 
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