elmo180
Posts: 8
Joined: Mon Oct 22, 2012 7:39 pm

High range WiFi dongle

Tue Sep 16, 2014 2:16 pm

Hello everyone,

I am currently working on RC car controlled by raspberryPi and I have succeeded with controling it by wifi(using smartphone/tablet) and by Bluetooth 4.0 and PS3 pad.
The problem that I'm struggling with now is range of the controller. I know that I cannot rely on Bluetooth so much because it will be about 30m maximum (however the BT specs says that it is max 10m), but what about WiFi connection? Now I am using very small Edimax dongle, so ofcourse range won't be impressive, but can you recommend any WiFi USB dongle that suits Pi power resources and has nice range? What can you say about this one http://www.buyraspberrypi.com.au/raspbe ... ss-dongle/ ?

It is very important issue for me because after I finish piCar I am willing to build drone controlled by raspberryPi :)

InitX
Posts: 13
Joined: Tue Sep 16, 2014 9:12 am

Re: High range WiFi dongle

Thu Oct 16, 2014 12:53 pm

You can change the wifi antenna to get better signal and there are directional antenna you can choose if you just need one direct.

User avatar
jeanleflambeur
Posts: 157
Joined: Mon Jun 16, 2014 6:07 am
Contact: Website

Re: High range WiFi dongle

Thu Oct 16, 2014 2:36 pm

Try the alfa awus036h. It's very sensitive and powerful.
You'll need a powered usb hub if you have a model A though.

User avatar
aTao
Posts: 1084
Joined: Wed Dec 12, 2012 10:41 am
Location: Howlin Eigg

Re: High range WiFi dongle

Thu Oct 16, 2014 2:51 pm

You cannot really get a "High power" dongle, the feedback from the transmit to receive signals would mess things up, both for higher output and higher sensitivity. However there are things you can do with antenna design these either make the antenna bigger or directional, neither particularly good to put on a RC car. There are of course 2 sides to WiFi, namely the router. If the router was in the middle of the cars domain then you immediately cover its range better, if this is not possible then an antenna that covers only the area the car will inhabit will also improve things. A superior solution would be to have antennae placed around the area the car will be and wire them back to a single WiFi router (with plug in antennae) or several WiFi repeaters spread about.
>)))'><'(((<

User avatar
jeanleflambeur
Posts: 157
Joined: Mon Jun 16, 2014 6:07 am
Contact: Website

Re: High range WiFi dongle

Fri Oct 17, 2014 8:54 am

aTao wrote:You cannot really get a "High power" dongle, the feedback from the transmit to receive signals would mess things up, both for higher output and higher sensitivity. However there are things you can do with antenna design these either make the antenna bigger or directional, neither particularly good to put on a RC car. There are of course 2 sides to WiFi, namely the router. If the router was in the middle of the cars domain then you immediately cover its range better, if this is not possible then an antenna that covers only the area the car will inhabit will also improve things. A superior solution would be to have antennae placed around the area the car will be and wire them back to a single WiFi router (with plug in antennae) or several WiFi repeaters spread about.
Actually you can get high power wifi dongles and they do work. While it's true that indoors higher power doesn't mean better reception due to reflections, outdoors you do get better range. Couple it with a circular polarized antenna - which better rejects reflections - and with a high sensitivity receiver and you can achieve hundreds or thousands of meters of range.
There are numerous forums dealing with long range wifi between 2 static points so they focus on high gain (>30dBm) highly directional antennae which are not good for a RC car or quad.
For a moving target my advice is:
- ad-hod network between the ground station and the vehicle.
- omni cloverleaf antenna on the vehicle. It has a gain of 1.2dBi so almost a spherical radiation pattern which is desirable
- onmi cloverleaf or (only with antenna tracking) a directional 4-12dBi helical antenna
- a high sensitivity wifi adapter - like the alfa I mentioned in my first post. It has -96dBi @ 1-2Mb/s and -91dBm @ 11Mb/s
- if your legislation allows it, turn on high power mode on the alfa for an extra 10dBm.

Some things to note:
- 6dB translate in double range. So a 7dBi antenna will give you double the range of a 1dBi antenna. Same is true for the transmit power - but note that 6dB means 4 times the power and only twice the range.
- you need line of sight at this frequency. 2.4Ghz penetrates very little and even foliage will kill your link. Due to the long wifi re-connection process, you want to avoid disconnects at all costs
- mount your antenna as high as possible on the car.
- use circular polarization.
- bandwidth drops as signal gets weaker. This is normal and you have to take it into account

@elmo180
Having said these, you might be better of with something like this:
https://www.sparkfun.com/products/10153
It's way lower frequency so better penetration, longer range. Very sensitive (-121dBm) and pretty powerful (20dBm) and has more than enough bandwidth for your needs (128-256Kb/s)


-

elmo180
Posts: 8
Joined: Mon Oct 22, 2012 7:39 pm

Re: High range WiFi dongle

Fri Oct 17, 2014 10:12 am

@jeanleflambeur

thank you very much for detailed answer :) I also planned that maybe just for start and first tests I will grab some Access Point with bigger antennas and power it from my car, so it should work for higher range.
jeanleflambeur wrote: @elmo180
Having said these, you might be better of with something like this:
https://www.sparkfun.com/products/10153
It's way lower frequency so better penetration, longer range. Very sensitive (-121dBm) and pretty powerful (20dBm) and has more than enough bandwidth for your needs (128-256Kb/s)
-
I had also though about some solution like that but I am little bit noob at these... How I can connect with transceiver like that? It should be some big controller like for ready RC vehicles or what?

soe ye htet
Posts: 5
Joined: Fri Mar 09, 2018 3:33 am

Re: High range WiFi dongle

Fri Mar 09, 2018 6:11 am

HI

https://www.buyraspberrypi.com.au/raspb ... ss-dongle/

have you tried with that one. Is that one is omni directional antenna? I am going to purchase it because it can support for 800 meters for outdoor and thats what I need in my project. Any suggestions are warmly welcomed

elmo180
Posts: 8
Joined: Mon Oct 22, 2012 7:39 pm

Re: High range WiFi dongle

Fri Mar 09, 2018 8:06 pm

I've replied already in private message but write it here as well, maybe it would be useful for someone else :)

I didn't try this one, although I really doubt that it will achieve such great range - mostly because of power that RasperryPi is capable to deliver. Maximum range that I was able to achieve(outdoors) was about 100-150m but it wasn't very stable.
I don't how this one, but all of Wifi dongles with antennas and more power freezed Rpi because it's power consumption and in my project it was not possible to use some more powerful power source,(like AC charger) because of it's mobility.

User avatar
Ronaldlees
Posts: 293
Joined: Sat Apr 16, 2016 4:28 pm
Location: North Carolina, US
Contact: Website

Re: High range WiFi dongle

Mon Mar 12, 2018 8:18 pm

elmo180 wrote:
Fri Oct 17, 2014 10:12 am
@jeanleflambeur

thank you very much for detailed answer :) I also planned that maybe just for start and first tests I will grab some Access Point with bigger antennas and power it from my car, so it should work for higher range.
jeanleflambeur wrote: @elmo180
Having said these, you might be better of with something like this:
https://www.sparkfun.com/products/10153
It's way lower frequency so better penetration, longer range. Very sensitive (-121dBm) and pretty powerful (20dBm) and has more than enough bandwidth for your needs (128-256Kb/s)
-
I had also though about some solution like that but I am little bit noob at these... How I can connect with transceiver like that? It should be some big controller like for ready RC vehicles or what?
It's been almost 50 years since I did any RC cars, but I did find this on the internet:

https://bobparadiso.com/2013/09/03/rc-c ... sing-xbee/

He is using joysticks and an arduino, but probably it could be adapted to a Pi I'd guess. He has code on his github. The frequency (900 MHz) seems more suitable for longer range than WiFi. Just a guess.
I am the Umbrella man: IR3/IR5 UV a/b/c OTS specs: break free, live life. Note that red cannot be seen with IR lenses, so cross at stop lights only on white walk signals, don't drive or operate machinery with lenses on, and don't use in low light.

Return to “General discussion”

Who is online

Users browsing this forum: No registered users and 22 guests