Do SMA Extensions Degrade FPV Signal? - DJI Digital Signal Loss Test

  Рет қаралды 1,821

Fab FPV

Fab FPV

3 жыл бұрын

This is a short video to test the amount of signal loss when using extension cables or adapters to connect the FPV Goggles to the Antenna(s). I’m using the DJI FPV Goggles V1.
The test scenario, like the other ones that I do “in-house” (check my playlist of technical videos using fixed ground station for receiving and transmitting antennas : • Dahsware - How to inte... , consists in the drone (transmitting antennas) in one corner of my room, and the goggles (receiving antennas) in the opposite one, with lots of rooms and concrete in between.
To ensure that the receiving antennas remain in exactly the same position during the tests, I’m using a self built ground station (a microphone stand with some 3d printed parts), with 4 holes to install the cables that subsequently go to the goggles.
The ground station has been set-up with 3 stock antennas, connected to to Goggles via rg58 coax cables, leaving the top left connector in the goggles free (the one close to the channel indicator leds).
In the first test, I connected my best receiving antenna, the TrueRc Sniper II, directly to the Goggles in the free connector, pointing in the direction of the transmitting antennas, and recording a 2 minutes DVR video.
In the second test, I connected the Sniper II at the ground station, in exactly the same spot where I kept the goggles before, and connected the Sniper II to the Goggle through a thin RG174, 2 meters long cable, and made another DVR recording.
Lastly, I replaced the thin RG174, 2 meters long cable that connected the Sniper II to the goggles, with a thicker, RG58, 1 meter long cable ( www.thomann.de/gb/pro_snake_s..., and made the last DVR recording.
I averaged all the samples of each recording, and here’s the results :
1. Direct connection between Sniper II and Goggles : 35,7 mbps
2. 1 meter thick RG58 cable to connect the Sniper II to the goggles : 30.2 mbps ( - 15% signal )
3. 2 meters thin RG174 cable to connect the Sniper II to the goggles : 11.7 mbps ( - 67% signal )
Also, I made a separate test to compare the signal quality when using a small adapter, in this case a 5 cm long, semi-rigid, SMA male to SMA female adapter. The result, as can be seen in the background videos, tells that the usage of an adapter brings a -15% signal loss, passing from 23.9 mbps to 21. That’s a huge loss, and can be avoided buying antennas that have natively the same connector as the VTX / Air unit that they will be connected to. In the case of the DJI system, I suggest antennas that have a MMCX connector. Of course it’s simpler to get a 3d printed TPU part and use MMCX to SMA adapters for the DJI AIR UNIT, but -15% signal is the price to pay. I will definitly switch to native MMCX antennas for the DJI Air Unit, after having seen those numbers.
Result analysis :
If you want to use a cable extension to connect the Goggles to the FPV Antennas, you really need to buy the best cable you can put your hands on. RG58 or LR400 / LR240, large coaxial cable diameter, double shielded, gold plated connectors, etc. Otherwise the signal loss will be simply too much and it wouldn’t work.
In my case, the idea of using my fixed ground station “in the field” for long range flights would have the PROs of always having the receiving antennas pointed in the right direction and elevation (that means to always have the best signal possible), and also relieving me from the stress of keeping my head still. In the CONs, of course, there’s the -15% signal loss.
I don’t have enough elements to evaluate this “on paper”, so I guess I’ll have to try it in the field and see what happens. I’ll try to follow the same path of a previous mission with the same configuration, but with the ground station and 1 meter rg58 cables, and compare the results.
Stay tuned and see you soon

Пікірлер: 14
@Rcschim
@Rcschim 3 жыл бұрын
Thanks for taking the time, very good results. I think when I tested cable effect back a few years ago I had a cheap thin one ;) By always having a good orientation on the groundstation vs high gain antennas on the head which you can never aim right, you will get more than the 15% back I guess ;)
@fabyt68
@fabyt68 3 жыл бұрын
Hi Mario I just made a video on the same path with the same antennas but mounted on the goggles, i'll try to put them side by side in order to appreciate the difference... also, in this new video I get to the limit of the DJI FPV System, like you forecasted at a certain point the bitrate just drops to zero withut warning and bye bye....wait for it
@divingfalconfpv4602
@divingfalconfpv4602 3 жыл бұрын
Yea seen a test. Video did side by side flight same direction & altitude.. goggles at times would drop then go back up cause I guess he moves his head.. lol.
@PKNEXUS
@PKNEXUS 2 жыл бұрын
Great video, thanks for this.
@aarrodri
@aarrodri 3 жыл бұрын
Your videos are great. Keep up the good work. I'm curious, since the mmcx to sma has a loss, do you think stock Dji anntenas connected directly to the air unit are better than LR anntenas ( for example the triumph) connected with adapter? I saw your prior video testing a bunch of anntenas but Dji stock was not in the test.
@fabyt68
@fabyt68 3 жыл бұрын
that's a good question, i didn't try that, but i can tell you that the loss with just even a small cm mmcx-to-sma adapter is significant... i think it's a close call between stock antennas directly connected, and a premium couple with adapter..... i'll test that in a next video.
@paulolobo837
@paulolobo837 2 жыл бұрын
Is there any amplifyer to use with dji fpv but just like a repeater not via cables?
@divingfalconfpv4602
@divingfalconfpv4602 3 жыл бұрын
So my iflight patch with that thin cable to attach like 2in or a lil more. Loses some signal. Damn
@MrGuardian84
@MrGuardian84 Жыл бұрын
..Teoricamente farebbe meno male rispettto al collegamento diretto in termini di radiazione assorbita?
@lorenzocascone2038
@lorenzocascone2038 2 жыл бұрын
is the same if i put a pigtail (9cm) on the caddx vista to extend the antenna lenght ? i loose quality signal ? grazie !
@fabyt68
@fabyt68 2 жыл бұрын
Si, qualsiasi connettore o cavo aggiuntivo aumenta leggermente la perdita di segnale. Anche dei semplici adattatori da mmcx a sma provocano un leggero ma concreto svantaggio. Sinceramente però questi dettagli hanno senso solo per long range estremo, danno quel vantaggio per passare da 12km a 13km, ma per la maggior parte dei voli la differenza è quasi impercettibile.
@lorenzocascone2038
@lorenzocascone2038 2 жыл бұрын
@@fabyt68 grande grazie io lo uso su un un geprc baby crocodile 5, voglio passare ad un mezzo che resiste meglio al vento e che possa andare oltre un 5", non un 7 che e' troppo pesante secondo me, che ne pensi di un 6" ? hai mai volato con un rekon 6 ad esempio ? e' leggero ha eliche piu' grandi di un 5" e copre distanze maggiori che ne pensi ? per distanze intendo anche 3-5km solo andata su in montagna
@fabyt68
@fabyt68 2 жыл бұрын
Non ho mai provato 6 pollici, però se ti interessa un minimo il long range ti direi di andare direttamente al 7 pollici. Non ha particolari difetti, ci faccio pure freestyle tanto quanto i 5 pollici, e ci sono molti più componenti
@brownsquirrel2828
@brownsquirrel2828 8 ай бұрын
I bought 4 5.8 GHz 5v radio frequency amplifier’s I later found out I need to add a filter to that haven’t actually tested I did test a 5v powered amplifier on the tx side which seemingly degraded performance idk if I should use a Ff filter for that I took it off never tried the rx amplify
DJI O3 FPV Antennas - Everything You Need To Know
15:01
Mads Tech
Рет қаралды 23 М.
FPV Antenna SWR & Gain - What Affects Performance Explained
30:10
No empty
00:35
Mamasoboliha
Рет қаралды 8 МЛН
Smart Sigma Kid #funny #sigma #comedy
00:40
CRAZY GREAPA
Рет қаралды 9 МЛН
Long Range FPV Ground Station - Build Tutorial
15:27
Adam G does FPV
Рет қаралды 56 М.
Remote ID Compliance for Drones: Everything YOU Need to Know
14:29
I Found The SECRET to Long Range FPV ( $60 HACK to go 6km! )
14:45
Adapter and extension cable loss testing
8:22
Video Aerial Systems
Рет қаралды 9 М.
Тест дальности DJI O3 Air unit со стоковыми антеннами
8:47
MY FPV SIGNAL SUCKS?! 😤 WHY?
18:00
Mr Steele
Рет қаралды 143 М.
Walksnail Avatar VRX Ground Station
6:38
FPV University
Рет қаралды 9 М.
Effect of using adapters and bending the co-ax cable
8:23
Painless360
Рет қаралды 8 М.
ДОМАШНЕЕ ЭСКИМО//ПРОВЕРКА РЕЦЕПТА ТИК ТОК
0:24
ОЛЯ ПЕРЧИК
Рет қаралды 4,1 МЛН
🥹Он герой (shawn_cnhk on IG)
0:15
Бутылочка
Рет қаралды 5 МЛН
Телега - hahalivars
1:00
HAHALIVARS
Рет қаралды 6 МЛН
REAL OR FAKE?
0:10
dednahype
Рет қаралды 12 МЛН
Mummy naya le aayi 🥰
0:36
Cute Krashiv and Family
Рет қаралды 49 МЛН