getting into fpv

[wafflejock]

I think eachine is a good entry point like I said but also skyzone makes some sleeker looking goggles that are still very good for the price. I do believe digital is the future but DJI still has some more latency to the video than I'd like (especially given astronomical price), perhaps I just need some better antenna as well just using stock on the goggles so far, the image quality is incredible though with digital, for analog it can be very good as well but will always have some analog "noise"/snow to deal with.

 

[wafflejock]

Oh also all said let us know what you end up getting and how it works out always curious to get more opinions on these things.

 

[miky94]

Yes the idea is that, I bought the Eachine ROTG02 and the app seems reliable, not the dvr but I can use the screen recorder of the smartphone, latency is not much more than that of digital fpv systems.
the EV100 should be the Eachine entry level goggles you said for about 100$ but I'd like to consider other alternatives.

 

[miky94]

ops I didn't see other replies, I'll take a look to skyzone too.
for the cruise flights I intend to do latency shouldn't be a problem, of course for racing I'd go for a full analog system.
I signed up on velocidrone but seems there is not a free version

 

[wafflejock]

Bummer on velocidrone must have gotten rid of the demo option too, looks like fpv freerider still has free demo but really not as good in my experience compared with the others.

 

[miky94]

Yes I think flying an unrealistic SIM is counterproductive

 

[miky94]

despite is dark, cold, and snowy, I'm flying at least a battery a day plus Liftoff at night. I broke one of the antennas of the receiver so I ordered the FS-X14S that seems to be the best FlySky now and I broke the beeper but still blinks.
now I can stay in flight for the whole battery life doing eights but LOS and angle.
I'll try doing the same but FPV with the ROG02 and smartphone or computer while I choose the goggles, for now I found:
€25,79 Quanum Cyclops
€45,10 BETAFPV VR01
€55,21 Eachine VR D3
€80,78 Eachine EV100
€73,20 Eachine EV800D
unfortunately they are all big except the EV100 but from what I understood is has antenna diversity and not receiver diversity and small screens.
acro is still a bit difficult on the SIM and since I''ll fly to film and not to flip I'm not sure whether to insist on acro or get into bad habits on angle, I think I'll try FPV angle on the Flywoo while I train acro on the SIM and then switch to it when I will have goggles, maybe it's worth to try the Acro Trainer Mode instead of angle or horizon

 

[wafflejock]

Yah think for fast but smooth cinematic shots acrobatic flight can be good since can lock the angle and center the sticks and the quad will continue on the current trajectory the trick is making it looks smooth since any input on the sticks results in motion on the quad (diving mountains for example, check out some of ledrib/drew's ones especially when flying islands and other locations, good example of cinematic acro . For slower cinematic shots I'd say angle mode plus ideally a gimballed camera with independent control is really the best option but probably requires pilot plus camera man and isn't something you can easily just get out to a park and do yourself I don't think (using iNav or otherwise gps/compass control with waypoints for quad and then just acting as camera man is an option but probably easiest if have a couple people working together). Nothing wrong with angle mode either just the quad self corrects which means motion in the view not controlled by you but self correction instead, a lot of people fly tiny whoops fpv and angle mode for racing just recommend against horizon mode because of unpredictability/uncontrolled motion with the flips and rolls.

This one is probably more flippy floppy than you're wanting even but can kinda see how drew's flying and edits are some cross between cinematic flow and freestyle tricks:

Another from mr steele think he did this one acro too though could have maybe been achieved with angle mode cause keeping it tame

 

[wafflejock]

Not comparing myself to these guys since they are pro and I am weekend warrior, but here's what one of mine looks like where I was just trying to get some cool shots of this local landmark and historic site turned museum:

 

[miky94]

yes I think angle mode is ok for cinematic, even the DJIs don't fly acro, but to not get into bad habits I'll continue to train it on the SIM and maybe I'll try acro trainer.
once succeded to look at the phone instead of the drone FPV is even easier than LOS, delay is not a problem but even with small camera angle is easy to increase and hard to decrease altitude when you don't know what's underneath from 300m, if I low too much the throttle I hear the drone go crazy in free fall and fog doesn't help too.
on the OSD the RSSI value was fixed at 51 and the link quality was fixed at 9, at the end the min RSSI was 51% and the min link was 99%, I didn't wire the receiver's RSSI, not sure what do they mean.
max current was 9A, does it mean I could fly like this with 10A continuous li-ion cells?
I also want to try GPS hold

 

[wafflejock]

Unlikely that max current was accurate. You'll need to calibrate the current sensing or have escs that report current back to the FC either with bidirectional d-shot (I think it supports current readings from esc back to the FC) or with dedicated wire from esc to FC (usually marked as "telemetry" or "sensor" and gives current info back to the FC). Usually will draw something like a few amps per motor max just cruising around when punching the throttle for take off or to gain some altitude or save yourself from a fall or turn then amps go up as the FC demands the ESCs to change the motor speed and the esc let's more current through and changes the gate timing to adjust the motor speed it could draw up to the max of either the motors escs or battery (whichever gives up first).

Also was going to mention sometimes I do a flip or roll just to get a quick peek of what is below me so I know where it is safe to descend, but it is important to fly places slow and or walk them first before ripping around faster

 

[miky94]

yes I don't know where that value comes from, bidirectional DShot is disabled in Betaflight, what about RSSI and link values?
in fact to see below I had to pitch to the maximum

 

[wafflejock]

I think link quality is the one the pros say is more of a standard. RSSI is typically sent by your TX on a channel like its a stick or a switch and in betaflight in the receiver tab it has an option for which channel to consider RSSI. If in that tab you see a channel bouncing around especially based on moving or blocking your TX antenna then that one is probably RSSI. Personally I just check my perimeters slowly but have only ever had one fail safe because I flew below a hill I was standing on and had ground between me and the quad, video surprisingly held on until it crashed into some tall grass. Took me about 20 min to find but yah that's my story

 

[wafflejock]

My FrSky receiver gives me RSSI and has warned me of low signal strength on my OpenTX remote a couple of times now that I think about it but only ever the one fail safe. Generally I fly with Spektrum satellite receivers cause I like the auto binding but recently have tried some others just to see what options are a bit more.

 

[miky94]

you are right, the RSSI channel is AUX 8 that doesn't match any input on my TX and just stays in the middle (51%), I'll wire it on the new receiver, as maybe the weak link in the chain is TX - RX rather than VTX - OTG, I'll test it with the drone disarmed and also I'd test GPS hold as failsafe.

 

[miky94]

about the FPV system, now I'm flying with the ROTG02 with 1 Eachine dipole and 1 Eachine K-Loverleaves antennas and it is not bad but because of rain I'm flying in an empty covered market and sometimes I can't get a stable signal or I get a grey screen, maybe there is interference, anyway I'll try with 2 Eachine K-Loverleaves antennas.
the Eachine EV100 are the only cheap goggles I found enough portable for me but they don't have receivers diversity and maybe instead of taking a step forward I would take a step back.
what do you think? thanks

 

[wafflejock]

In general matching antenna are a good thing so think you'll probably get some improvement in the video signal by having same on both the VTX and the video receiver. The diversity antenna is most helpful I think when using a mix of patch and omni so you get pretty good local reception all around from the omni and better signal in one direction with the patch and then diversity can switch (or in some cases mix) the best signal before amplifying the signal and sending it along to the display. Regarding flying inside a place it kind of depends on the structure if there is a lot of metal surfaces or otherwise radio reflective stuff around then you can get "multi-path" reflections where one signal comes direct from quad to your goggles and another slightly delayed signal (same one) comes from quad bounces off stuff then gets to the goggles. If receiver in the goggles doesn't have some "intelligence" built in to ignore the extra multi-path signals (which I don't think they typically do) then being inside can actually be much worse than being outside in terms of signal. Really best case scenario is clear line of sight between you and the quad and the quad is way up in the air that way the signal is being broadcast roughly omnidirectional from the quad itself and if nothing between you and it and not a lot of things around you or the quad for the signals to bounce off of then things should be "most clear".

 

[wafflejock]

Also I'm not a radio expert, I'm a CS major (got a BS back in 2009 and just grinding since then) and just have an interest in these things for hobbies but I also made this alexa skill for studying up on taking the HAM test it will tell you the correct answer if you get a quiz question wrong and totals the scores over some number of questions (forget if I set it to 10 or 15) anyway you might find it useful for learning general stuff about radio waves and antenna:

Amazon.com

I probably need to update this skill for updated test questions since they change them every couple of years but the info is still somewhat relevant... also would need to figure out where I saved this repository and see if I still have access

 

[miky94]

No I meant on the video receiver, on the VTX I have the Flywoo antenna which is for long range, today I tried with 2 Eachine K-Loverleaves on the ROTG02 but even outside the building I couldn't get a reliable signal, it is surrounded by portcullis and so maybe flying close to it 600mW works worse than 25vw, the strange thing is that the other day it worked fine, maybe there is interference that was off, now I tried at home and there is not even a place where it loses the signal.
today I also lost the TX signal as soon as I took off, it also happens for a second when I land too violently, but the receiver is not very isolated, it has only one curled antenna left which also has lost the terminal protection

 

[wafflejock]

More power output can be bad because of the multi-path reflection and makes it worse because then just higher energy reflections that "look" more like valid good signals. When it comes to quads they do go through a lot of abuse so adding a bit of padded foam or thick double sided tape under things can help absorb some impacts but also I always zip tie my antenna and my battery wires to the frame since if they aren't strapped down they tend to get destroyed in crashes (either things wiggling free from connectors or otherwise getting chopped up by props)

Regarding the different radio links really you have two radio links just to be clear there is the video radio link and then there is the control video link (totally separate). The radio link uses 2.4GHz roughly (usually) and the video uses 5GHz frequency roughly. All the radios use some set of "channels" or ranges of frequencies for sending the signal that is somewhere around 5GHz (or 2.4GHz for control link), believe each channel is about 5-20MHz wide so say 5828MHz - 5848MHz might be considered "one channel".

Does your WiFi suck for video calls? Use 20MHz channels!

After years of trials and tribulations in San Francisco apartments, the single best thing I did for my home network was to switch most…

medium.com

^^ some good insight and detail in this write up about wifi and 2.4GHz vs 5GHz in that application.

Anyway TLDR I just meant it is good to have matching antenna for a given radio link. So say we are talking about the control link, it is "generally good" to have the same kind of antenna on both the RX and TX of any given link because the resonant frequency of the antenna is what allows it to both transmit and receive, so if two wires used as antenna are exactly the same length then they are effectively 'tuned' to the same frequency at a physical level. I say "generally good" to match because sometimes you want the transmitter to transmit in all directions and a receiver to be more directional or vice versa or may want both sides to use more of a "directional" antenna that basically blocks signal from one side and "sees" more of a signal in a particular direction.

Back to the mutlipath thing I believe polarized antenna (cloverleaf style) typically are good at rejecting some of the bounced signals because the signal is polarized by the antenna and the receiver has the same polarization and anything not aligned to that polarization will be ignored (pretty sure when signals bounce off things the signal polarization changes).

Also regarding your particular issues, it could be running the VTX at higher power output is creating too much heat or has in the past created too much heat on the VTX and so it's malfunctioning at the higher output levels too (or just drawing too much current for whatever is supplying it). Making sure it has an adequate power supply and the power is "filtered" with a capacitor can help with some of those issues but kind of a lot of guess and check (this is where oscilloscopes really come in handy, can get a cheap one that can be somewhat helpful for debugging PWM signals etc. but I eventually decided to get myself a nice fancy sigilent one... cause this is the kind of thing I like to nerd out about)