When is 1W not necessarily 1W?! // DIGITAL VTX Output power testing

[@madtoffelpremium8324]

tldr: everybody is lying

[@ChrisRosser]

Except me! In data we trust. 😁

[@gabyguay6990]

Aha! 😅

[@imignap]

Tldw gdit

[@spartan3299]

Sure would like to see the HDZero Freestyle VTX. Very useful data result Sir RF.

[@Simofly]

Chris thank you very much for all the hard work you are doing for this hobby ! This is an amazing video this is what we need in FPV will became patron asap

[@TweakRacer]

Joshua Bardwell is an RF engineer who mentioned that we should use the higher frequency channels so common WiFi won't interfere. Maybe that's why the lower frequency channels on the VTx's use a higher output. Also, the O3 system may look like it's transmitting at about half the output power of the v1 stuff, but maybe that's because it's transmitting on 2.4GHz (less power needed for the same range/penetration as 5.8GHz). As for the battery testing equipment, maybe borrow Bardwell's? He raised money for it a long time ago and did some testing.

[@MrPashee]

AMAZING test. Very surprising results... Thank you Chris!

[@nullcure]

Chris how much time does it take you to do this research and testing and being able to understand it in order to bring us this wonderful content?

[@ChrisRosser]

The work for just this video was around 60 hours.

[@disco.volante]

Great findings! I always fly CH1 and this explains why I get fairly far out with my 200mW HDZero VTX. Antenna manufacturers could also offer antennas optimized for CH1, most FPV antennas from the analog age perform best at 5800MHz afaik.

[@j005u]

Another banger! I really enjoy this new in depth direction.

[@flyinryanfpv]

Just became a Patron! Can't wait to see more of these types of test as well as the battery test! Cheers Mate 🍻

[@sunnyfpv3694]

No surprise to me. All of them use identical 802.11x frontends which are limited to 27dbm power. There is no chance it can go higher

[@Vousie]

Pretty sure the HDZero Freestyle VTX does hit 1W output power on R1...

[@sunnyfpv3694]

@@Vousie Ok, but can how the stream quality compares?

[@Vousie]

@@sunnyfpv3694 HDZero has a great image. And remains at low latency. And doesn't just fully drop the link and remain gone when you go just barely out of range and come back. People who do mountain surfing have learned that the hard way...

[@sigterm15]

@@sunnyfpv3694 I thought these devised use LTE baseband modems.

[@Vousie]

Thank you very much for these tests. Very puzzling results, though, given how good DJI's range & penetration generally is, even compared to 1W analog VTXs... I'd love to see you test the HDZero Freestyle VTX (and the Freestyle V2 VTX when it comes out) as well. 26:00 Don't the DJI VTXs increase/decrease their output power depending on where the goggles are? So you wouldn't see their max output power unless you had the goggles on the other side of the house? 27:40 Or, alternatively, maybe the extra processing for the O3 algorithm meant they had to reduce the output power to keep the thing from overheating?

[@bransonclayton]

Great data.Thank you for your time and presentation. It helped me better understand.

[@timechaser4313]

Chris, is there any chance that DJI 03 could increase power output more if the signal degrades? As in the Tx moves farther away from the goggles? So a kind of dynamic power output when not in a static situation?

[@devinfritchey7323]

I was thinking the same thing

[@devinfritchey7323]

Accoridng to chatgpt, a 250mw signal would be received at 3.5mw over 13km, assuming line of sight and normal atmospheric conditions of 25c at 50% humidity. 3.5mw is well above the operating range of wifi receivers so maybe it really is that weak of a signal operating at those distances. Hard to believe

[@sigterm15]

@@devinfritchey7323oh my god. does anything you said make sense to you?

[@bloatedgoatfpv]

I'm interested in knowing results from an HDZERO Freestyle VTX.

[@MCsCreations]

Fantastic testing, Chris! Thanks a bunch! 😃 Stay safe there with your family! 🖖😊

[@hazzahfpv6675]

@Chris Rosser now that "low-band" is supported by the HDZero VTXs and considering that they have the highest output power on R1 (the lowest frequency supported so far), would you be interested in testing if the low-band frequencies give even more output power, as their frequency is even lower)?

[@xfOL.]

super interesting! much respect for all you do

[@p.1206]

Surprised you didn't test the HdZ freestyle. The size of that thing and it's heatsink might show that it's got some serious amplification in there. 30db for Qam is no joke. I wonder if the hdzero dropoff towards R8 has to do with the MCU not assessing the PA power detection properly at different freqiencies, or more likely that they use a PA that amplifies digitally modulated signals more efficiently at lower frequencies specifically in the dance of WiFi. Also, considering that HdZ is running 200mw+ at the 25mw settings and people at racing events weren't complaining (racers loved the clearer video), I wonder if they'll change their minds about the typical 25mw limit.

[@Vousie]

Well, many race organisers check the output power of each person with an RF power meter that they have with them (you can often see it on the screen in livestreams) and everyone's transmitting about the same amount (including analog pilots), so either these readings are not quite accurate or the pilots *are* using the 25mW adjust option to bring it down to the correct levels.

[@The_1ntern3t]

It'll be very interesting to see DJIs reaction if an unlock for the Vista O3 firmware happens.

[@willpowerfpv3246]

there is an "unlock" for the 03. The Ham file..

[@crisnmaryfam7344]

@@willpowerfpv3246 lmfao...

[@dexdevlon]

This is a really well made video, would love to see the results for the new OpenIPC hardware.

[@stormriderfpv]

@ChrisRosser that's amazing content 👍 About the 03 and Vista on O3 firmware: Isn't the O3 protocol increasing power automatically relatively to the distance from the goggles (or received bitrate)? From my experience on the field, the O3 air unit + goggles 2 has been outperforming everything I know, that would be really incredible on such low power. How is DJI doing the impossible? Am I missing something? It would be interesting to test the power with the goggles being far/osbtructed from the O3 unit.

[@disco.volante]

O3 has higher latency than its predecessor, this would increase range and penetration for a given output power. The actual output power is about the same as the V2 system at 700mW, as Chris presented in his video.

[@crisnmaryfam7344]

@@disco.volante higher latency would not inherently increase range and penetration for a given output power... Latency is basically a measure of time delay... technically - "the delay before a transfer of data begins following an instruction for its transfer." Long story short, higher latency in any situation is Bad.

[@ericnelsonnn]

I am curious about this too. DJI claims 33dBm EIRP (2000mW) on the 5.8 frequency. If the O3 only outputs 200mw (23dBm) as shown in this test, even if they double it by adding both antennae, that's 400mw or 26dBm. That leaves 7dB to make up with with the omni antenna. I don't see that happening. I also don't them only using half of the front ends total power capacity, but then again, the O3 turns into an oven, so maybe it just thermally can't handle 400mw.

[@Yith]

Great video, but I would love to see the results with the other HDZero VTXes, Race V2, Race V3 and especially the Freestyle VTX.

[@petersvideofile]

Great video! Is there any feedback from the goggles to the airunit regarding signal strength, to allow automatic power output control. This is how regular dji drones work as far as I know. It doesnt sound like it for these standalone vtx, but If there is, you might need to attenuate that signal to force it into a higher power mode....

[@baggszilla]

Awesome freaking work Chris! You da Man!

[@FPVSlice]

Nice video! I've also always wondered if the DJI digital system (receive and send digital goggles) could be harmful for human health with long term usage. I know this is non ionizing radiation, but we are still talking about microwaves being transmitted right beside your scalp. It would be really interesting to see a video about this topic!

[@Flying_Wild_Boar]

Thank You Chris for Yours amazing job ;)

[@M-H433]

Absolutely brilliant Chris,wonder how long before the manufacturers chime in,I think they need to answer up.....

[@gregdavidd]

On the O3 chart he shows 7 channels so I guess he was in 20Hz mode. I wonder if that makes some difference when in 40Hz mode instead with only 3 channels.

[@honeybeedrones5510]

Excellent investigative work thanks Chris

[@joshuamacdonald8785]

Thanks so much for this explanation! One question about the range increase section being an inverse square relationship, you noted to get a doubling of range you need to times the power by 4 wouldn’t the range side of that equation stay linear? So wouldn’t it be for each addition of x distance you would times the power by 4 instead of for each doubling of x distance? Thanks so much!

[@micsherwood4930]

Damn, that is BRILLIANT!

[@marianofpv]

Hi Chris, wonderful video. In your previous video, Caddx stepped in and said that they do increase the goggles transmit power in the higher power modes. It would be nice to understand how that affects the range and penetration, if at all. I imagine that it must be mostly acknowledge packets, so it could be affecting latency?

[@Vousie]

To acknowledge packets, and to tell the VTX to resend ones that it has missed... Looks to me like the DJI system *has* to have a full picture - when it can't get a full one (even with low resolution tiles) it fully drops the link instead of being able to just show static in the spots it's missing. So a lower goggles transmit power would mean it would fully drop the link earlier.

[@IanF-FPV]

I’m curious to see the output power from the Avatar VRX and googles for the transmit side. Same for DJI.

[@Simofly]

+1 !

[@MessingWithCode]

Great Video , i really enjoy your video!!!

[@KwaddawK]

How do you run O3 firmware on the vista? Is that by updating the vista on the DJI assistant - consumer drones series app rather than the original FPV series app? I fly with V2's with both O3 air units and vistas and switch between the two operating systems in the goggles and my vistas are on the 1.00.606 firmware still.

[@BuddsSkyCam]

You did the test on the 03 with the FCC hack and at 40hz? There are 3 different power modes with the hack on the dji03: 10HZ, 20HZ, 40HZ. Did your test show that all 3 gave the same output?

[@aphinion]

You integrated the power consumption ^^ Glad to know the cap in output-power does correlate with power drawn and they are not just burning part of that energy in extra heat. The O3 being on par with 700mW Vista also explains a lot of what we see in real life (and it feels quite good to know I can just leave it as it is and it will perform just fine). Is there an explanation for why higher channels generally tend to produce less output power? And I would also be curious about the foxeer, rush and tbs >1W analog VTX claims when measured side by side!

[@LucianoVeryNiceHi]

i bought three rush max solos to be able to fly next to dji pilots but i am still having bad signal to the level where i gave up flying with other people. when i am alone or with analog pilots, penetration and range are ridiculous compared to 69, unifys or trump nanos that i had so far

[@ChrisRosser]

It seems to depend on the VTX. Some VTXs produce more power at higher frequency and some more at lower frequency. I'm not sure of the exact mechanism though.

[@ValleyFPV]

Very Nice info. However why no data on the HD Zero Freestyle vtx?

[@BogHopperFPV]

Chris - if I’m correct you’re comparing the ‘power’ and therefore, by proxy, the likely range and penetration of analog and digital systems using RMS If the digital systems rely on picking up their data at the peak of the crest aren’t they likely to have significantly better performance than analog at the same RMS power Is it time now for some long range tests or more likely set up a series of obstructions (metal or concrete walls) and zigzag through them for a ‘real world’ type test? Brilliant work so far

[@Halfrightfox]

You're doing God's work, Chris

[@janzajicek9246]

How to get Caddx Vista with O3 FW as you mentioned in video? Just update DJI FW via Assistant to latest version?

[@cyclops-fpv]

Very very interesting,so my Walksnail avatar is better on lower channels! without your testing I wouldn't of known that,i changed that immediately after the fact.looking forward to your battery testing,keep up the good work Chris your a legend👍

[@sten6537]

But channel 7 is the most far away from wifi and other crap so people still get better range on some higher channels

[@mrvelocity3428]

so whats the max gain antenna you could put on the walksnail v2 transmitter without voiding eirp?

[@tecknolt2695]

Good video Chris!

[@coilockerfpv]

I am forever on channel one now 😂

[@andre-7423]

Well done, I expected a spectrum analyser, dut well done! 😊

[@ChrisRosser]

Glad you enjoyed it! Unfortunately I can't afford a spectrum analyzer but these RMS power meters are really good for giving you a total mW output. Although I'm sure a $10K analyzer can integrate total power as well.

[@aphinion]

Isn't the resulting graph kind of one? XD

[@davidbopi]

No it's not. A spectrum analyser shows the spectral components of an individual signal by converting it to the frequency domain (via FFT for example).

[@hotkatgotama]

Hi, I didn't how else to ask this question, apologies. I am building my first drone with your AOS UL7 EVO - could you give me some advice on where on the frame I should install a GPS module. Also, could you make a GPS Mount available on Thingiverse. I also like your 5" frames - maybe next year :) sorry, also - all the 3D prints on Thingiverse appear to be for the AOS 5 - do most of those work on the UL7?

[@EliProductions]

Thanks so much for this comparison! For your last point about the vista running O3 firmware with possible improvement in range, does that apply to the OG Air Unit as well or is it a vista only thing? Thanks!

[@saturn_fpv]

20:00

[@AmisCorolla]

Very good info!

[@miquelmarti6537]

it would be interesting to also compare hd0 Race v2 against v3

[@ryanbeall7542]

I know typical Ocusync on say a Mavic automatically adjusts QAM modulation factor and output power based on closed loop SNR. I'd be real interested to know what they are doing on these fpv units. Might be worth looking at a spectrum analyzer to see if the receiver is actually transmitting back to transmitter to close that loop to keep link stable. Maybe an easy test would be to see what power does with the receiver on vs off.

[@ryanbeall7542]

Oh yeah, of course it's a two way link on the DJI fpv units... You can control your drone on the same link. Yeah I'd be they 100% use the same scheme as they do on the Mavic to keep the link stable. My point is that the link you are measuring may not be the same modulation or transmit power given the fact that the receiver/goggles isn't turned on etc. I'd bet that the actual conducted power changes in response to the goggles. Be real cool to set up a variable attenuator on the goggles and watch the power output of the tx side real time on a scope

[@pioneer987654321]

thnaks for this interesting video

[@scienteer3562]

Don't know, but suspect the 03 firmware waveform has a higher Peak to Average Power Ratio(PAPR). It would need to back off on RMS power to prevent peaks distorting.

[@ChrisRosser]

That may well be the case. I wonder if O3 getting very hot might also limit how hard they can drive the amplifier.

[@Dr.Bojie-Chan]

@@ChrisRosser I agree with him as well. I think that's called slew-induced distortion? From your data, it looks like they are running these components to the edge. The output power is reflected in how far the amplifier can push before distortion(vs frequency/modulation characteristics). I'm sure heat is a factor, but the capability of the amplifier to resist distortion at higher frequencies is probably the bigger bottleneck. I will say though, RF is a bit of an artform... I could be completely wrong lol

[@califpv]

if your not recording on the 03, there should be no problem running 1200mw

[@VoltageLP]

Do you have a similar test for analogue VTX?

[@JoshuaHardee]

It’s funny, I always thought the vista performed better than the OG AU. Now I know why. Appreciate your efforts. As far as the battery testing, you should reach out to Bardwell, he did the same crowd funded batt tester buy and completely dropped the ball. Took him forever to test, then goofed the up the tests. He’s got all the expensive equipment collecting dust at his house, may be he would be open to sending it to you so that you can perform the tests he was unable to do.

[@mrlazda]

Maximum EIRP of 2 antenna is equal of 2 times EIRP of single anttena. To be more specific, "the gain realised at the beam peak is equal to the number of elements times the gain realised in the same direction when only one element is excited" that is from antenna array theory. Only radiation patterns will not be the same as for single element. Edit that was commonly used in long wave AM transmission from beginning of last century to shape coverage of radio broadcast. Even now is sometime used by radio amateurs.

[@ChrisRosser]

Yes that's true but don't the antennas have to be oriented in the same direction? DJI specifically recommend the antennas be oriented in different directions.

[@mrlazda]

@@ChrisRosser now from point of maximum EIRP, statement is "true". To explain more if we have two ideal isotropic antennas then no mether of how they are oriented they have gain of 1 in all direction (EIRP is same as output power) so gain of 2 of them will have gain of 2. For practical case when there are (most commonly used) monopole or dipole and they are at angle of 90 degrees (worst case) then gain of two antenna would be same as single antenna, but they already have gain of 2 sp in both cases EIRP will be same and 2 times output power of transmitter. I am not too familiar how specific VTX use antennas (I usually do not fly FPV, I am old and I perfer flying turbine jet plains and helicopters), but there is option that they even produce with two linear polarized antennas at 90 degrees and proper pashe shif circular polarisation (i do not know why they would use that, but that is commonly used for satelite communications when you use two Yagi antennas at 90 degrees to get circular polarisation). If I remember correctly you are expert in matlab, and matlab have tools for simulation of antenna radiation pattern, so maybe you could do simulation what they do (I was only basic matlab user and thay was before I retired from work over 12 years ago).

[@mrlazda]

I found on FCC site presentation how you calculate EIRP for muti antenna system (including cases with cross polarization) transition.fcc.gov/oet/ea/presentations/files/apr16/5.3-MIMO-Primer-RB.pdf

[@kandredfpv]

I laughed when I saw (what I thought was) the Eachine TX805 on your bench because I know for a fact it doesn't do the claimed 800mW, but using my Immersionrc RF power meter I was seeing ~600mW 🤦‍♂️

[@DriftaholiC]

Did you test the 03 with the ham file?

[@ChrisRosser]

Yes that's how I got it in fcc mode.

[@k4x4map46]

nice!!!

[@stevefox3763]

I have a 2.4ghz digital setup running 4w in the WiFi band :)

[@thegentlestories214]

what if I have a ham license for Europe?=)

[@mlentsch]

More gold.

[@mu7095]

Thank you for explaining, very useful. Yeah batteries are another mystery. You can't get something for nothing, but the weight vs mah conundrum + c ratings, it's not helpful, especially for noobs like me.

[@Curiousity0309]

So o3 firmware on a vista makes it worse than vista on original firmware?

[@stormriderfpv]

Maybe the power is increased automatically with distance

[@Curiousity0309]

@@stormriderfpv I do have such thoughts, that because o3 is all dynamic in real world it would do that. But then again, I also remember that Chris unlikely would have missed this detail with how thoroughly he tests everything.

[@LucianoVeryNiceHi]

interesting and unexpected. i am the only analog pilot between DJI pilots and even though i equipped all my drones with rush max solo (2.5w) i am still having horrible time and range when i am flying with even one DJI pilot... with three, it feels like 200mw vtx. it happened on two different quads so i am highly confident it's just DJI and not my builds... can you test where DJI roams when it's set on any channel, and what goggles are transmitting?

[@Voyajer.]

Yeah it seems dji video signals really mess up analog if its anywhere near the same frequency. Do your dji pilot friends move to their higher frequency channels so you can use R1?

[@LucianoVeryNiceHi]

@@Voyajer. yeah i am always on R1, regardless, i have such crappy time that after a year of trying to solve that, i literally decided to give up flying with other people. i don't feel that it is ok that i am bullied into buying digital equipment but it seems to be a requirement if there is even one pilot with digital system...

[@ChrisRosser]

The killer with DJI is the goggles transmit so you can't actually stand anywhere near dji pilots. If you're flying with DJI pilots you have to stand far away from them (which sucks). A more powerful VTX won't help that much if you're 1-2m away from the DJI goggles.

[@THEVISON]

G.O.A.T.

[@RickLaBanca]

That ham limit isn’t correct. Jb always uses that old lawsuit as an example but the fcc regs don’t have that limit since video is not a control link. In spite of that poorly written ruling.

[@peterpizzurro]

I have my HAM license right next to my RID modules. Lol

[@danthemancasey]

TBH you probably should have used a dedicated ADC instead of the built-in ADC on the Arduino. Much more accurate.

[@davidbopi]

The slope of the ADL5902 (without voltage scaling) is 53 mV/dB. A 10 bit ADC with 5V vref has 4.88 mV/LSB so allows to measure ~ 0.1 dB/LSB. Do you really more precision than that?

[@CarftyCarper]

Well this is going to upset alot of people :)

[@ChrisRosser]

I hope not. In general I've found that explaining how these systems perform makes people happier with the performance of their gear.

[@RickLaBanca]

One can conceive the power loss by looking a garden hose at jet vs wide spray.

[@visioneerone]

im stealing that for the next time I have to explain how antenna gain works

[@VoltageLP]

lol, I'm transmitting 50W EIRP without a license practically every day 🤣🤣🤣

[@eme4289]

This is sooo disappointing. I had no idea that digital was putting out such low power. A nice test would be to put up an analog vtx against a digital vtx and test range at same output power.

[@JanDaliba]

Díky!

[@woutchauvaux6672]

Damn chaos pro vtx is extremely disappointing in its actual power output

[@ruliaramchauhan841]

5Oh

[@Fpv_sean]

So Which vista firmware will be most efficient then ? Grate testing btw 🤌

[@tektkite7255]

hey doofus, why not test the hdzero 1W vtx and the current race vtx v3? also how is your set up calibrated?

[@mikebergman1817]

Hey doofus, give it time.. I'm sure he will.

[@davidhoward2901]

This guy is the last guy I would be name calling on KZbin. How you look rn 🤓

[@tektkite7255]

@@davidhoward2901 Ok, Doofus. haha

[@davidhoward2901]

@@tektkite7255 doofus 🤓

[@davidhoward2901]

Nobody cares about Canadian politics like you do buddy 🤓