DJI FPV best RANGE which Antennas on Goggles and Air Unit

While doing "wingsuit style" DIVES with my quad in the alps, the last thing I want are RED RSSI indicators making me nervous. I was quite sure that my AIR Unit antennas are not placed optimal, and I knew there was more potential on the goggles antennas as well. Since DJI logs Bitrate for you in a file, you can test antennas and compare the LOG data in excel.
After this test-sessions on the field I swapped the menace patch with an ORT 3turn helical - it has a flexy SMA cable and better performance as well.
Overall I'm pretty confident with this VIDEO TRANSMISSION now!


►EQUIPMENT
Filmed with: Panasonic GH5 + R0de VideoMicro, Samsung Galaxy S10

AndyRC on DJI FPV best Antenna-Setup

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VIDEO INDEX:
00:52 1st flight: baseline (bad Airunit Antenna placement)
01:54 2nd flight, better AirUnit Antenna placement
02:33 Goggles Antennas Optimization
04:32 RP-SMA, RPSMA to SMA converter

DIVES like in the old days - but with modern gear

Hi dear RCSchim blog reader,
been busy flying with the Sector 5 (HGLRC, Review here) with DJI FPV system installed, Crossfire for control link and this all topped with Gopro7 in 4k30 with hypersmooth. I can't believe how much the technology has evolved in the last years (see my first DIVES and these new ones in comparison to see what I mean).

6S Battery Comparison (Racing Drone Packs)

That's a long video, USE the Jumpmarks in my VIDEO INDEX below for easier access to what matters to you. Grab some popcorn and whatch the whole thing if you've got time :)

If you're curious about how to CONVERT DJI SRT files to be useable in Excel, find the script here on a google drive: https://bit.ly/2waB7vD
There's also the FULL XLS Sheet I used in this review, check out the data in detail there.
I've included a 2nd SRT converter script there to re-format those SRTs for the essential infos (VOLT + Latency + Bitrate). If you want to get a tutorial how to overlay the data in a video (as I have here) let me know. If there's enough interest in it I'll do a tut...

!DISCLAIMER! - Banggood sent me most of the Packs for review, you can buy them here:
1 Beat Lipo 1300mah  also use: Code for this one, BGFS12P, 12%off
2 iFlight Fullsend
3 Tiger Power Atomic Platinum 
4 XF Power 1300mah 
5 Tattu R-Line3 1300mAh 
6 Gaoneng GN3
7 DemonRC 1250mAh 
8 DemonRC 1100mAh 
9 AHTech Infinity 
10 CNHL Black Series 1300mah 
2020 Banggood Spring Sale

While some of those links are affiliation links I dont earn money here (it's the banggood contact who tracks sales) - I'm not a sales guy, here you get HONEST reviews and opinions.
I'm kinda biased tho if you send me a Baseball cap or a shirt ;)

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VIDEO INDEX:
01:33 ● XF Power
02:44 ● Beat Lipo (1st Test)
04:00 ● Tiger Power Atomic Platinum
05:19 ● DemonRC 1250mAh
07:27 ● Gaoneng GN3
09:09 ● iFlight Fullsend
11:10 ● AHTech Infinity
12:21 ● Tattu V3 (cold)
13:25 ►reTest!
13:54 warm Batteries
14:13 ● Tattu R-Line3 (pre warmed)
15:35 ● Beat Lipo (pre warmed)
17:23 ● CNHL Black Series (pre-warmed)
18:27 ● DemonRC 1100mAh
19:56 SRT conversions
20:22 DJI Logging issues
21:20 Sandisk sd card
21:54 ►►ANALYZE! See the Data!
24:06 DJI Ant issue
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A quiet place

It's unreal how normal everything looks, beautiful spring weather and yet we have totally different situation than a few weeks ago. Look at it from the positive side: nature can take a deep breath and the animals already conquer back some normally crowded city streets...
All the best for you and your family, dont freek out, go fly (alone) and help flattening "the curve" by social distancing!
Good examples how to socialize online whilst staying at home:
RecRoom
https://rec.net/user/Schim
See you there (but be warned, I have "some" experience in Lasertag :)

XMas Treewipfls - Global warming edition (Speedy freestyling at Sonnleit...

DJI FPV HD System (draft)

I'm preparing the DJI FPV systems review (my current project, lot's of fun, very interesting!).
You can already see my own notes and get a ton of info from it - or you wait until my video is finished and consume it with some popcorn...
The txt file above is a work in progress...

Antennas  - for example - look like this:


First video: Latency test - see what I found while measuring it on the oscilloscope:

iFlight Cinebee75HD honest Review and Flight footage

!DISCLAIMER! - Banggood sent me this product for review, you can buy it here   (I DONT use affiliation links - I'm not a sales guy, here you get HONEST reviews and opinions).
Acessories:
4 Pairs Gemfan 3-blade
iFlight 1103 Brushless Motor

RCSchims Ultimate FPV-Antenna test 2019 (many omnis, patches and helical...

EXCEL RESULTS sheet
Same test 2018
Aaronia Spektran review (the DB measurement device)

!DISCLAIMER! - ORT sent me some antennas for review, you can buy them here
Banggood sent the Foxeer Lollipop 3
I DONT use affiliation links - I'm not a sales guy, here you get HONEST reviews and opinions.

My test-setup:
I use 1mW on the transmitter, 5m distance to a VERY SENSITIVE receiver (Aaronia Spectran HF6065 -150dB!) and take enough samples from the -DB reading on the display to get an average.
The VTX is warmed up before the test - this way I can be sure it stays at the same output level for all antennas. This is not 100% accurate. On start I had 815uW and after 1h testing it showed 1029uW or 1mw - but this should not impact measurements too much!
Time Rank Type -dBm -dBm ant. null (or 90°sideways for directional)
00:21:32 1 dir. -45,3 -64,8 ORT Helix 6 Turn
00:20:14 2 dir. -47,4 -68,6 Circular Wireless Helix 12dB
00:18:23 3 dir. -49,3 -69,1 ORT Helix 3 Turn
00:15:50 4 dir. -50,3 -79,9 Triple Feed Patch 9.4dB
00:16:45 5 dir. -51,3 -70,1 VAS Crosshair Extreme
00:15:00 6 dir. -51,6 -68,5 Triple Feed Patch 8dB
00:09:48 7 dir. -52,2 -65,2 IRC Spironet Patch 8db
00:10:25 8 dir. -52,2 -68,2 Menace PicoPatch
00:14:17 9 dir. -53,4 -67,6 Foxeer Echo Patch
00:11:54 10 dir. -54,4 -67,7 ORT DualShield
00:11:02 11 dir. -55,9 -67,4 ORT Shield
00:03:42 12 om. -56,6 -70,2 Foxeer Lollipop 1
00:03:23 13 om. -57,5 -76,5 Aomway SPW blue
00:08:07 14 om. -57,8 -78,3 ORT 6Lobe SPW
00:07:40 15 om. -58,8 -68,6 Foxeer Long coax Pagoda pro
00:04:20 16 om. -58,9 -70,6 Foxeer Lollipop 2
00:06:55 17 om. -59,6 -80,0 ORT Pagoda
00:05:59 18 om. -59,8 -71,5 SpeedyBee Antenna
00:04:50 19 om. -60,0 -72,7 Foxeer Lollipop 2 Stubby
00:05:34 20 om. -60,0 -69,8 Foxeer Lollipop 3

Treewipfl Surfing - relaxing Freestyle after a long day...

This was a new spot for me - first packs carefully flown there - got better with each pack tho :) Just about the best sense of freedom after a long business day and some hours behind the steeringwheel...

Flew my SpeedyBee 5" drone with Foxeer Box 2 (+ND16 filter) in 1920x1440 converted to 2560x1440 Superview with NIEK script (more here: https://youtu.be/uoD4vURHBGs), upscaled to 4k60 for best youtube codec - hope you like the effort :)

Please support with 👍 and 🔔 thanks ;-) it helps a lot!

FPV Cam Latency

Download (or preview online!) the most current > XLS Latency Sheet
FPV Cams "Latency" or "LAG"


It is very important to see what your FPV plane/copter "sees" in REALTIME and react to eveade certain model death within milliseconds!

There is always some delay involved - but you should choose components to keep this minimal.
With high latency flying FPV feels like being drunk. Flying a non stabilized copter get's impossible soon - you fly worse than you actually need to. While you may not notice latency directly - without it you can become a better pilot. 

What components have an impact on latency?
+++ FPV cam:
Time from image capture (lens, chip) - to the output on the video cable.
Between those 2 events you have the image processing on the cams chip - so the right cam is important. See the Latency Excel Spreadsheet for most current measurements.

Older cams could add as much as 100ms of latency - this is REALLY a big deal!
Current cams are down as low as 5ms.
One problem here:
"unsharpness of measurement": each 16 or 20ms (NTSC or PAL) you get a new image. This means 60 or 50 pictures per second. it wont get faster than that (on analog video).
So everything below 16ms cant be directly measured. The moment you hit a signal (power on LED in my case) can be at a random position within this timespan of 16ms.
So I repeat many measurements and look for the lowest latency and the average - which is the probbability of seeing stuff the right time :)

+Video Transmission:
ANALOG transmission DOESNT use buffering. It doesnt use hightech chips that have to calculate a lot of stuff - it just transmits a power-signal (Video encoded in NTSC or PAL) over the air.
IT DOES THIS AT THE SPEED OF LIGHT!  (~ 300.000km/sec)
So the myth "over distance latency increases" is bullshit.
OK - if you're flying to the moon (384.400km) - it will get noticeable - but within reasonable distances you can forget it (each 300km would mean 1ms latency added).
I was able to measure video latency - but it's really in nano-seconds range on my oscilloscope :)

DIGITAL transmission however - this is another story. You have to ENCODE images (lots of them) into numbers - transmit them - and decode them on the other side. Clever minds try to make good algorithms and fast chips - but we're not there yet. Fastest systems are around 50ms - which is quite high compared to analoge vid...
See my review of the FPV Blue system - one of the most promising, very community interactive, projects that actually work, and can give great results!

++Control link:
So: you have a fast cam, see the obstacle (jumping tree, branch,...) asap - but HOW LONG does it take to convert the THUMB movement on your remote's stick to a control correction on the plane (servos) or copter (motor RPM change).
Drone Mesh did some good tests (also with osciloscope and decoding of signals on the screen).
I tried to test this myself - that's a lot of work - not finished my video to this - will update you. In the meantime whatch his videos!
No final results yet, it's a complicated matter - but I noticed the difference between ezUHF and Crossfire! - even between FrSky and Crossfire):
  FrSky 2.4ghz   20ms
  TBS Crossfire  12ms
  ezUHF              40ms  (but there is a lower latency mode I have to test yet!)


Latency testing method:
Better to probe the video cable (from CAM) directly, or measure the effect of the LED on the screen with a photo diode?
I decided to go back to the screen/photodiode method, because this is what you call "glass to glass" latency - the practical application for the enduser.
Additional benefit: This method allows us to compare digital and analog systems' latencies (since measuring video cable directly only works for analog).

Update 4/2018: in my last Video (Sparrow micro 2) I've come back to also testing cams "direct" with the video cable method. Newer cams can be tested for lantency very accurate now. Something has changed: on the video "curve" I see the light change immediatley - and not in "frame level accuracy". This takes away the 16-20ms inaccuracy. I saw that new cams like Foxeer Predator or Runcam Sparrow 2 have 1.3ms!!!

These are sketches of the two test methods (to maybe understand them easier):


see my video here for some closeups and details about the 2 test methods (starts around 03:00):


Also check "Drone Mesh" - he did quite similar testing here: