Hello Tello Pilot!
Join our DJI Tello community & remove this banner.
Sign up

Repeater positioning and how it influences video quality [Concluded]

Guorium

Well-known member
Joined
Jan 21, 2019
Messages
369
Reaction score
146
Hey all I did a test to confirm @raulvolador ’s claim on “separation between phone and repeater = better vid”. It was pretty windy and my tello drifted many times but I have the results in.

I flew diagonally across my local football field which is 120m one way. Then return. Height maintained at 5m (it was windy so at times I had to adjust it). I recorded the trips with 3 setups.

1, plane mode bt off just control by phone.
2, plane mode with t1d connected via bt, fly with repeater bounded to the bt controller.
3, same as 2 except I had the repeater hanging on the fence 3m to my right.

I used iphone x running 1.3.0 offcial app, 1.11 fw for t1d and 01.04.78.10 fw for tello. Tello was always rebooted after all other devices before each test.

The first setup had nice vid until 50m then it all breaks down, at 60m I wasn't getting any video feed and I had to turn around. So first lesson, use a repeater haha. I deleted the vid, useless. Due to time constraints I missed the repeater + phone control tests. In pursuit of the best performance and practicality I will try carry that and more tests out tomorrow. Day 1 tests are conclusive enough that having the repeater away is better. Therefore day 1 tests will not be repeated on day 2 and the day one results cannot be directly compared to day 2 results. PS: I repeated day 1 tests and got less differentiating results than day 1.

The for the vids I upload. I counted frame skip for them, 1st vid was on setup 2. 2nd vid was on setup 3 suggested by Raul. 3rd vid was a repeat of setup 2. Notice how sometimes the vertical angle shifts, it is a result of EIS shifting the frame in high wind, not a frame skip due to interference so this does not count.

Day 1

1st vid 6 skips (Setup 2, repeater bounded to controller)
link
2nd vid 1 small skip while turning (Setup 3, away from repeater)
link
3rd vid 3 skips (repeat of setup 2)
link

So needless to say. I think Raul's suggestion worked nicely! I had the least frame skip when the repeater is away from me. But would I be bothered to carry a stand with me or seek a place for hanging repeater every flight for the sake of avoiding a few frame skips? Probably not... I would try hanging the repeater when it is practical though. What you do is entirely up to you!

Day 2 [With bt controller: Head mount, chest mount, gound placement 3m away and at my feet. Without bt controller: repeater 3m away hanging on a fence and then very close to the phone.]
*all other conditions are the same as day 1
**45 deg back looks like ( /me), 45 deg back 3m away looks like ( /____________me)

Setup

Head mount

Chest mount

Ground 3m vertical away

Ground vertical at feet

Ground 45 deg back 3m away

Ground 45 deg back feet

Ground 45 deg back 3m away replicate

Frame skip count

7

4

10

4

10

5

12

Video link

link

link

link

link

link

link

link

It turned out that 3m away from the repeater on the ground was pretty horrible and repeater on the ground in general isn't too good. So I pushed the repeater about 3m forward to get to a slightly higher ground spot that is more level to the rest of the field. 4 more tests below for that.

Setup

Ground 3m vertical away

Ground vertical at feet

Ground 45 deg back feet

Ground 45 deg back 3m away

Frame skip count

4

2

2

6

Video link

link

link

link

link

Hey being on the ground isn't too shabby when you stand next to the repeater!

I decided to run the same tests I did on day 1 since I had the time. Plus the phone + repeater results. Very close means repeater as close to the phone as setup 2, far means 3m apart. Both close and far are at chest height.

Setup

Setup 2

Setup 3

Phone & repeater very close

Phone & repeater very close replicate

Phone & repeater 3m apart

Frame skip count

3

2

3

2

4

Video link

link

link

link

link

link

Final verdict: Best result is a achieved by running the setup at chest height, having the repeater 3m away maybe marginally better (a few extra skips over a 120m long return flight in slow mode). Ground placement is usable but I noticed noticeably weaker signal compared to chest height at the 120 mark although the number of frame skips aren't so much different (1 skip difference). 45 deg angle could help with high altitude signal (need to test this) not so much more helpful at 5m height than vertical. At least on iPhone X having the bt controller connected doesn't make video noticeably worse than using the phone alone. Given the convenience, tactile feeback and comparable (to setup 3) video quality of setup 2 shown by results above, I would prefer to use setup 2 all the time. I consider the improvement by repeater separation marginal.

Disclaimer: This experiment was by no means scientific despite my effort to approach that. Ideally one needs many more repeats to obtain a convincing result. The large discrepancy between day 1 and day 2 in terms of the setup 2 & 3 comparison indicates there is still a chance where there is no statistical difference between the 2 top setups.

Update: I had a chat with a Rhode & Schwarz technical officer who is very knowledgeable about RF antennae. He explained that when the receiver is too close (half lambda) to the antennae it is in what is called near field regime where it cannot "see" the transmission wave very well. The separation is smaller than half of the RF wavelength which is about 6.1cm. In my setup 2 the rough antennae separation is about 13cm from xiaomi logo on the repeater to the centre of my iPhone X's wifi antenna. So I think the separation is large enough in my setup.
 
Last edited:
My favorite spot is the power bank in my front "vest" pocket extender sticking out. Horizontally mostly, no difference in vertical that I could tell. Can you test this also? I'm curious. I have had excellent results. It's so handy for long distance or iffy situations cause it's already in my pocket ready for a tello rescue. For FPV I use a 10' pole so I have 360 coverage around my house more or less. I stick a small foil covered paper plate between the extender and power bank via a small hole.
 
My favorite spot is the power bank in my front "vest" pocket extender sticking out. Horizontally mostly, no difference in vertical that I could tell. Can you test this also? I'm curious. I have had excellent results. It's so handy for long distance or iffy situations cause it's already in my pocket ready for a tello rescue. For FPV I use a 10' pole so I have 360 coverage around my house more or less. I stick a small foil covered paper plate between the extender and power bank via a small hole.
Ok i already have a setup like ur vest pocket method. I have a neckloop I use to hang the repeater in front of my sternum. (I really justed meant a vest is too cool for me) I will test that too tomorrow.
 
Last edited:
  • Like
Reactions: xcrost
To all,
A question, when I connect with my remote control T1d-928F with the Tello, I get no camera image. I also can not turn on photos or videos with L1 or R1. The buttons for photo or video in the Tello app on the smartphone are then locked. Is that correct? Is there a solution to take pictures with the T1d ...?
Thanks for the feedback
 
To all,
A question, when I connect with my remote control T1d-928F with the Tello, I get no camera image. I also can not turn on photos or videos with L1 or R1. The buttons for photo or video in the Tello app on the smartphone are then locked. Is that correct? Is there a solution to take pictures with the T1d ...?
Thanks for the feedback
not normal. If t1d connects with controller app on ur phone no problem then u should try update fw for ur controller. Gamesir t1d upgrade helper search that in app store
 
  • Like
Reactions: xcrost
I am finally done lol. Vids coming up next day if you don't believe the numbers. Glad to see my setup is up to par.
 
  • Like
Reactions: xcrost
Thanks for all of your input! I love data. I'm still tweaking/experimenting with my different setups. I'll share when they are more conclusive lol.
 
  • Like
Reactions: Guorium
thank you for that much effort, but I was thinking, how much easier it would be if there was a way to make Tello connect to a Wi-Fi network. Could use a sectorial antenna with range of kilometers!
 
thank you for that much effort, but I was thinking, how much easier it would be if there was a way to make Tello connect to a Wi-Fi network. Could use a sectorial antenna with range of kilometers!
It's actually pretty easy but then there is flight time. You add the weight that makes it even worse. By the time you get to max distance now more or less you don't have enough batt. to get back.
 
It's actually pretty easy but then there is flight time. You add the weight that makes it even worse. By the time you get to max distance now more or less you don't have enough batt. to get back.
No problem. I know this limitation. So, how to make Tello connect to my Wi-Fi network?
 
thank you for that much effort, but I was thinking, how much easier it would be if there was a way to make Tello connect to a Wi-Fi network. Could use a sectorial antenna with range of kilometers!
no problem. glad to help. Usually my return flight time over that 120m test course is 1:40 in slow mode, lets say I take away 5 seconds for the turning. That is a rough estimate of 960m on the conservative side. Definitely not up to your kilometers range expectation. Tello EDU can join a network but I think it is in the programming side, you need to run some sort of programming software.
 
I'm not sure how you set it up but this guy used a 4GLTE dongle attached to his fixed wing drone. They can travel much farther distances on a single battery.
 
I'm not sure how you set it up but this guy used a 4GLTE dongle attached to his fixed wing drone. They can travel much farther distances on a single battery.
Oh I saw this. It was bloody amazing. However it was a disco. He enlarged battery cavity in the foam body to accommodate 2 much larger cells.
 
  • Like
Reactions: xcrost
Hey all I did a test to confirm @raulvolador ’s claim on “separation between phone and repeater = better vid”. It was pretty windy and my tello drifted many times but I have the results in.

I flew diagonally across my local football field which is 120m one way. Then return. Height maintained at 5m (it was windy so at times I had to adjust it). I recorded the trips with 3 setups.

1, plane mode bt off just control by phone.
2, plane mode with t1d connected via bt, fly with repeater bounded to the bt controller.
3, same as 2 except I had the repeater hanging on the fence 3m to my right.

I used iphone x running 1.3.0 offcial app, 1.11 fw for t1d and 01.04.78.10 fw for tello. Tello was always rebooted after all other devices before each test.

The first setup had nice vid until 50m then it all breaks down, at 60m I wasn't getting any video feed and I had to turn around. So first lesson, use a repeater haha. I deleted the vid, useless. Due to time constraints I missed the repeater + phone control tests. In pursuit of the best performance and practicality I will try carry that and more tests out tomorrow. Day 1 tests are conclusive enough that having the repeater away is better. Therefore day 1 tests will not be repeated on day 2 and the day one results cannot be directly compared to day 2 results. PS: I repeated day 1 tests and got less differentiating results than day 1.

The for the vids I upload. I counted frame skip for them, 1st vid was on setup 2. 2nd vid was on setup 3 suggested by Raul. 3rd vid was a repeat of setup 2. Notice how sometimes the vertical angle shifts, it is a result of EIS shifting the frame in high wind, not a frame skip due to interference so this does not count.

Day 1

1st vid 6 skips (Setup 2, repeater bounded to controller)
link
2nd vid 1 small skip while turning (Setup 3, away from repeater)
link
3rd vid 3 skips (repeat of setup 2)
link

So needless to say. I think Raul's suggestion worked nicely! I had the least frame skip when the repeater is away from me. But would I be bothered to carry a stand with me or seek a place for hanging repeater every flight for the sake of avoiding a few frame skips? Probably not... I would try hanging the repeater when it is practical though. What you do is entirely up to you!

Day 2 [With bt controller: Head mount, chest mount, gound placement 3m away and at my feet. Without bt controller: repeater 3m away hanging on a fence and then very close to the phone.]
*all other conditions are the same as day 1
**45 deg back looks like ( /me), 45 deg back 3m away looks like ( /____________me)

Setup

Head mount

Chest mount

Ground 3m vertical away

Ground vertical at feet

Ground 45 deg back 3m away

Ground 45 deg back feet

Ground 45 deg back 3m away replicate

Frame skip count

7

4

10

4

10

5

12

Video link

link

link

link

link

link

link

link

It turned out that 3m away from the repeater on the ground was pretty horrible and repeater on the ground in general isn't too good. So I pushed the repeater about 3m forward to get to a slightly higher ground spot that is more level to the rest of the field. 4 more tests below for that.

Setup

Ground 3m vertical away

Ground vertical at feet

Ground 45 deg back feet

Ground 45 deg back 3m away

Frame skip count

4

2

2

6

Video link

link

link

link

link

Hey being on the ground isn't too shabby when you stand next to the repeater!

I decided to run the same tests I did on day 1 since I had the time. Plus the phone + repeater results. Very close means repeater as close to the phone as setup 2, far means 3m apart. Both close and far are at chest height.

Setup

Setup 2

Setup 3

Phone & repeater very close

Phone & repeater very close replicate

Phone & repeater 3m apart

Frame skip count

3

2

3

2

4

Video link

link

link

link

link

link

Final verdict: Best result is a achieved by running the setup at chest height, having the repeater 3m away maybe marginally better (a few extra skips over a 120m long return flight in slow mode). Ground placement is usable but I noticed noticeably weaker signal compared to chest height at the 120 mark although the number of frame skips aren't so much different (1 skip difference). 45 deg angle could help with high altitude signal (need to test this) not so much more helpful at 5m height than vertical. At least on iPhone X having the bt controller connected doesn't make video noticeably worse than using the phone alone. Given the convenience, tactile feeback and comparable (to setup 3) video quality of setup 2 shown by results above, I would prefer to use setup 2 all the time. I consider the improvement by repeater separation marginal.

Disclaimer: This experiment was by no means scientific despite my effort to approach that. Ideally one needs many more repeats to obtain a convincing result. The large discrepancy between day 1 and day 2 in terms of the setup 2 & 3 comparison indicates there is still a chance where there is no statistical difference between the 2 top setups.

Update: I had a chat with a Rhode & Schwarz technical officer who is very knowledgeable about RF antennae. He explained that when the receiver is too close (half lambda) to the antennae it is in what is called near field regime where it cannot "see" the transmission wave very well. The separation is smaller than half of the RF wavelength which is about 6.1cm. In my setup 2 the rough antennae separation is about 13cm from xiaomi logo on the repeater to the centre of my iPhone X's wifi antenna. So I think the separation is large enough in my setup.
OK, since it's a repeater that you're talking about,
The reason it wasn't working properly so close to you is because that's not what it's designed for. That's not its intent or its purpose.
The repeater was designed to give you a signal farther away from the primary signal.
what I mean by that is, you're not using the repeater the right way if it's right next to you. The repeater is designed to be placed as far away from you as possible while still getting the same results.
for example, from where you're standing, operating your Tello, if you're flying to the north of the position or standing, the repeater should be placed as far to the north from you as you can get it while still delivering a proper signal.
this way, when you're flying,...let's just say 80 to 100 m to the north of your standing position, by placing the repeater 80 m to your north you can now fly 150 m or greater (to the north) depending on your environment and the surrounding interference.
you are repeating the amount of distance that your Wi-Fi is traveling successfully in order to increase the distance. By placing the repeater right next to you, you're defeating the point of the repeater altogether. using a booster with the repeater could give you greater range but the repeater by itself isn't tasked with increasing the signal strength. It is tasked with repeating the same signal. more of an understanding thing.
Best of luck
 
  • Like
Reactions: leeburridge
OK, since it's a repeater that you're talking about,
The reason it wasn't working properly so close to you is because that's not what it's designed for. That's not its intent or its purpose.
The repeater was designed to give you a signal farther away from the primary signal.
what I mean by that is, you're not using the repeater the right way if it's right next to you. The repeater is designed to be placed as far away from you as possible while still getting the same results.
for example, from where you're standing, operating your Tello, if you're flying to the north of the position or standing, the repeater should be placed as far to the north from you as you can get it while still delivering a proper signal.
this way, when you're flying,...let's just say 80 to 100 m to the north of your standing position, by placing the repeater 80 m to your north you can now fly 150 m or greater (to the north) depending on your environment and the surrounding interference.
you are repeating the amount of distance that your Wi-Fi is traveling successfully in order to increase the distance. By placing the repeater right next to you, you're defeating the point of the repeater altogether. using a booster with the repeater could give you greater range but the repeater by itself isn't tasked with increasing the signal strength. It is tasked with repeating the same signal. more of an understanding thing.
Best of luck
Perfectly said. I have been reading a lot as I'm new to drones but not tech (I am a very senior IT person with a lot of experience in many aspects and Wifi is one of them. I have watched videos where people have the repeater in their hand and I honestly despair but I guess they don't know how it works and it will generally help a bit because those devices have stronger signals than your phone.

I live in a rural area and I'm considering putting one outside my house high up around the roof area to give better signal for height more than distance. Being high up it will also give a greater range because it's up high away from other wifi signals from peoples broadband routers etc. also being high up buildings around me will not be blocking the signal as much.

It seems to be a lesser talked about subject on the radio capabilities and people just get the repeater and use it next to them to get a "bit more" range.

There's also very little talk about using mesh which you could use in a variety of scenarios with a Tello.

I'll give an example of a good use of an extender :

When I moved to my current house I had to wait three weeks for broadband. I was with BT which lets me use other peoples BT Broadband through BT WiFi for free. I bought a Netgear N200 (I think) and used a Raspberry Pi to do the authentication and managed to find a BTWiFi SSID which was pretty week. I used a power extension cord and a CAT5 cable and popped it up high outside the house, this was connected to my router. It gave me internet for those three weeks. If I put this "wifi extender" in the house the signal was lousy as the router I was connecting to was quite a distance away but outside away from the devices that were using the connection as much as possible meant that it worked well.

This is very similar to what people want to achieve with the Tello.

Basically you want the repeater to be as far away as possible from your phone and still have a strong signal but in the direction that you want to fly. This means that instead of have a 100m from your phone you will get 100m from the repeater which could be as much as 250 or more if it's placed well.
 
Perfectly said. I have been reading a lot as I'm new to drones but not tech (I am a very senior IT person with a lot of experience in many aspects and Wifi is one of them. I have watched videos where people have the repeater in their hand and I honestly despair but I guess they don't know how it works and it will generally help a bit because those devices have stronger signals than your phone.

I live in a rural area and I'm considering putting one outside my house high up around the roof area to give better signal for height more than distance. Being high up it will also give a greater range because it's up high away from other wifi signals from peoples broadband routers etc. also being high up buildings around me will not be blocking the signal as much.

It seems to be a lesser talked about subject on the radio capabilities and people just get the repeater and use it next to them to get a "bit more" range.

There's also very little talk about using mesh which you could use in a variety of scenarios with a Tello.

I'll give an example of a good use of an extender :

When I moved to my current house I had to wait three weeks for broadband. I was with BT which lets me use other peoples BT Broadband through BT WiFi for free. I bought a Netgear N200 (I think) and used a Raspberry Pi to do the authentication and managed to find a BTWiFi SSID which was pretty week. I used a power extension cord and a CAT5 cable and popped it up high outside the house, this was connected to my router. It gave me internet for those three weeks. If I put this "wifi extender" in the house the signal was lousy as the router I was connecting to was quite a distance away but outside away from the devices that were using the connection as much as possible meant that it worked well.

This is very similar to what people want to achieve with the Tello.

Basically you want the repeater to be as far away as possible from your phone and still have a strong signal but in the direction that you want to fly. This means that instead of have a 100m from your phone you will get 100m from the repeater which could be as much as 250 or more if it's placed well.
precisely.
happy you took interest.
I have no coding experience whatsoever even though Tello a classroom coding tool. Certain I could figure it out if I ever get around to it but I am very happy that someone took interest. The little Tello perform so much better than the other toy drones I had experimented with that it lead me to be The owner of around a half a dozen including the other models which I haven't even tried out yet. Tello EDU and Robo master.Yes that's hard to believe I just have a lot going on. had some interruptions.
those Tellos also lead to several dozen other full-size drones of high caliber status as it has become my favorite hobby.
that never would've happened without Tello.
i'm hoping to get them all set up in a room in the near future for photographs and I'll post!
I love making my own modifications, that's kind of what I get out of it but I enjoy having the ability to use most available features currently on the market.
 
  • Like
Reactions: leeburridge
precisely.
happy you took interest.
I have no coding experience whatsoever even though Tello a classroom coding tool. Certain I could figure it out if I ever get around to it but I am very happy that someone took interest. The little Tello perform so much better than the other toy drones I had experimented with that it lead me to be The owner of around a half a dozen including the other models which I haven't even tried out yet. Tello EDU and Robo master.Yes that's hard to believe I just have a lot going on. had some interruptions.
those Tellos also lead to several dozen other full-size drones of high caliber status as it has become my favorite hobby.
that never would've happened without Tello.
i'm hoping to get them all set up in a room in the near future for photographs and I'll post!
I love making my own modifications, that's kind of what I get out of it but I enjoy having the ability to use most available features currently on the market.
I am going to bet you are, like me, one of the early Rasp Pi adopters. I have used many over the years for computational stuff (Linux based) - pihole, vpn and media streaming. As soon as I realised there was a great community the thoughts started pinging everywhere. Rasp Pi with 4G and a VPN to my home network.... Phone on same VPN. This would vastly improve reception and range at a small cost but getting the signal over the GPS is the challenge. Probably not very expensive to setup but it would be a case of exposing the NIC on the Tello to the Pi instead of the onboard WiFi. I haven't looked inside yet but I'm going to guess that the NIC is on-chip with the CPU so may not be feasible easily. Have you read anything about this sort of setup? It's not even all about the long range but the better signal quality.
 

Members online

No members online now.

Forum statistics

Threads
5,711
Messages
40,008
Members
17,133
Latest member
Magtinez