I am contemplating whether to use wifi range extender or router (many have extender function) to extend the range of my wifi coverage. My project involves logging data in the field and uploading them to a server. I would like to use one mobile hot spot to access the internet and extend its range to cover several loggers. Right now I am using Arduino with wifi shield but the shield has an antenna that is rather small. I want to extend the mobile hot spot with an extender so it may reach the loggers, around 1,000 ft or hundreds of meters.
So does anyone have some experience with a range extender and how does it compare with a router with extender function, in terms of extended range? Thank you!
Base on Friis Transmission Equation, for sub Ghz chipset, if we select 300 Mhz v.s 900 Mhz band, the distance will be 3 times more. same thing if we select 300 Mhz v.s. 2400 Mhz, the distance will be 8 times more.
Thanks sonnyyu. I will not be able to use any wires. It's a field (i.e. grows plants). I could have shacks with car batteries inside to power these logger units but that's it! Since wifi is 2.4GHz I won't be able to extend a few hundred feet without huge antennas I guess? That's too bad. I'll give some extender some tests. Worst case: every logger gets a mobile hotspot.
The sensors are in a Tire Pressure Monitoring System (TPMS)
Pressure, gas law
Acceleration, car speed
Temperature, gas law
Battery Voltage, battery management
The requirement of system;-
-40°C ~ +125°C full specified operation
Battery have to last longer than 5 years
Atmel solution;-
A low-power low frequency wake-up receiver for Tire Pressure sensor of battery power management.
315/434 MHz ASK/FSK UHF Transmitter.
125 KHz LF Receiver.
Infineon solution;-
Since 2003, more than 150 million TPMS sensors of Infineon continuously improved product generations were sold worldwide.
SP37 Development RF Kit is Available in two “flavors”
Operating frequency of 315 MHz or 433.92 MHz
Output power of 8dBm
Infineon only draws 4 sensors per car so do I, but my Lexus SUV's spare tire has one of those which make me lost a big face when light lit and I send it to dealer repair.
In your case, no 125 KHz LF wake up, but same 315/434 MHz frequency wake up (battery power management). One tiny battery last 5 years.
315 MHz will give you 8 time longer distance than wifi.
liudr:
So does anyone have some experience with a range extender and how does it compare with a router with extender function, in terms of extended range? Thank you!
Yes I have some experience creating WiFi networks over longer distances. However you go about it, it can be a bit of a nightmare. A fixed installation is more straightforward than a roaming one but ultimately, WiFi was designed for short spans, under 75m LoS. Much less in noisy RF environments.
My gut feeling is WiFi is the wrong technology for the application. Unless WiFi's ubiquity is essential to the application, I see little reason to bother with it's drawbacks.
Have you thought about using XBee for the loggers?
Low power, spans measured in Kilometers, mesh-able networks. Seems to fit the bill.
I have no idea how XBee fits into the Arduino ecosystem though.
Thanks Matt. I should definitely try Xbee. I have no experience with Xbee. The reason I chose wifi was first to replace a cell modem and slow upload speed and bandwidth/month. WIth wifi and a mobile hotspot, I can get 5GB/month for 50USD so data and image uploads will be possible. The arduino wifi shield also provides an easy way to make connections to the server I'm using for data upload. So if I switch to Xbee, I wonder what would be the best way to keep this project working. Will I need to make a master module that collects things from slave modules (loggers) and relay to internet? I have no idea. Will the mesh network also extend the range that signal can travel?
I got ok results, but have to say this extender could be better (for example does not have connection for external / proper antenna).. So I can not recommend it...
I've currently Asus router as wireless router + extender + TP Link 703 (external antenna mod) and Arduino connected to rj45 of 703 with 5100 shield..
Maybe I should connect yagi-antenna to tp-link 703 and try directly to Asus..
Every 6 dBm Transmitter power gain will be double the distance. Here is gui of my Asus RT-N16 router which I flash with DD-WRT.
Default setting = 17 mW = 12 dBm
Maximum setting = 251 mW = 24 dBm
if I select 251 mW, The distance will be 4 times longer. I use this method to control my kids Internet access and keep it top secret, but now my last one is going to college soon.
Two rules to convert dBm to mW
Rule 1: The Rule of 3
If you raise the dBm value by 3 you double the mW value: