Long range connectivity Arduino--------

Using Arduino Project Guidance
1

Hello.
I have a project for a university that demand some long range connectivity among 41 arduinos..

i want to collect data with an arduino + xbee and 40 small arduino stations that they will return me data like temperature. from a agricalture area..

its a little tricky project and i need help , right now i am trying to find some workaround the connectivity between the "station" and the "clients", all this will be wireless , xbee i think is the most efficient protocol , because if i need to talk to station 40 for example wich will be 7KM away the "protocol" it self will gather the data from this station with the help of the others am i correct?

2

will be 7KM away

7 kilometers is a long way. Some of the XBees claim to support that range. Which ones might be appropriate depend on what country you are in.

xbee i think is the most efficient protocol , because if i need to talk to station 40 for example wich will be 7KM away the "protocol" it self will gather the data from this station with the help of the others am i correct?

The protocol has nothing to do with how the radios work. The mesh network XBees can be defined as coordinator (one per network), router, or end device. The difference between a router and an end device is whether the device also acts as a router. Generally, the end devices are configured as routers rather than end devices.

The XBees will help each other, but if the end devices are all 7 km from the coordinator, they can't provide much help to each other.

3

Thanks

7 km will be the "master" receiver from the last node the 40th one..

The node 38 to node 39 will be 200 meters approx..

The legal frequency for my country is 868mhz ...

The budget is small so I need some advice to save as Much as possible..
I am all ears for solutions.. Somebody told me to look at libelium waspmode also.. But this will defenetly add some "fences" for the project

4

An Xbee mesh seems ideal - you can add in additional routers to bridge your way from your base station to the remotes. However, they really don't fit your criteria of cheap, especially for a minimum of 40 nodes. Will you need an arduino at each node too? How will you power them all?

5

They will be near power . so power is not an issue..
So the idea of a x10 is also good don't you think?

6

How about something like this?

http://embeddedcomms.com/products/modems/rm-232-433bb.htm

Will there be any WIFI connectivity throughout the campus.

-Stephen

7

WiFi yes but not for the entire area

8

XBee's would be the way to go. Your biggest issue with trying to get that type of range will be RF Power levels.
I'm assuming your needing to have the system using "unlicensed" channels.

With unlicensed channels, the RF power levels will be limited to +10dbm to maybe +24dbm depending
on where you are in the world. So your simple little soldered on piece of wire isn't going to do the job.

Your going to need to consider your antenna system. High gain directional antennas will be needed.

I have set up many point to point systems in the 32-80 Km range with just +24dbm.

I have simplified this as much as possible to help you understand:

Fist thing you need to know is the power output of the RF module yours using. +24dbm is equal to about 0.25 watts.

Second thing you need to know is the receiver sensitivity of the RF module your using. Lets say its -100dbm.

Third thing you need to know is what the "free air space loss" is for the frequency range your using.
868Mhz has about a -91db loss per Km.

So you have a transmitter at +24dbm signal, a receive that needs a min of a -100dbm signal. You have about 115db of
acceptable path fade.

You need to understand the dbm scale. Dbm is an RF measurement scale based on 0 dbm = 1mW.
Every 3dbm increase doubles the level. So in this case if a +24dbm(+0.25w) transmitter increases to +27dbm the output is now
0.5watts.

You can increase the range by using directional gain antennas. Depending on the frequency and size limitations
you can take a signal that would have a radiation pattern of 360 degrees and concentrate that power in one direction.

This might be in the form of a Yagi antenna. They take the signal and direct a lot of the signal in one direction.
You still loose some to side and rear lobes, but you can get gains in the 6-18db range with about a 20 degree
beam width.

If higher gain is needed, you can use a dish antenna, something like a small satellite dish. They direct all most all
of the energy in one direction in a very tight beam width. Usually about 2 degrees with a gain of upwards of +32db.

As I said at the beginning, I have made distances of 80km with the correct antenna even with only +24dbm.

Systems gains would work something like this.

+24dbm (0.25watts) of actual RF power.
An antenna with the following gain would give you this:
+3db = 0.5watt ERP (ERP = Effective Radiated Power)
+6db = 1.0watt ERP
+9db = 2 watts ERP
+12db = 4 watts ERP

A 0.25watt transmitter with a +12db gain directional antenna will give you the effective power level of 4 watts.

Hope this helps you with understanding how you can obtain the 7Km range you need for your project.

9

gc9n:
They will be near power . so power is not an issue..
So the idea of a x10 is also good don't you think?

Why not using a PowerEthernet adapter and ethernet shields?

10

zoomx:
Why not using a PowerEthernet adapter and ethernet shields?

My understanding is those only work on a common phase of power, which is unlikely to be the case over a 7km area. Transformers between nodes block the data signals (and even without them, I'm not even sure the signals could still be readable after 7km of attenuation).

11

I am using the APC220 RF module which operates at 430MHz. Multi-point using RTC timer controller measurement stations, every 4 hours. Should be enough time to support 41 stations, with collision detect.
With a simple quarter wave antenna (16.5 cm wire) replacing the stock antenna, I can cover my whole 5 acre vineyard.
Agree with other replies that for 7 km distance you will need high gain antennas, direct line of sight, ... and a ham radio license depending on frequency used. Maybe use a GSM module shield.

12

I am using the APC220 RF module which operates at 430MHz. Multi-point using RTC timer controller measurement stations, every 4 hours. Should be enough time to support 41 stations, with collision detect.
With a simple quarter wave antenna (16.5 cm wire) replacing the stock antenna, I can cover my whole 5 acre vineyard.
Agree with other replies that for 7 km distance you will need high gain antennas, direct line of sight, ... and a ham radio license depending on frequency used. Maybe use a GSM module shield.

13

868MHz! Oh, you are in Europe. 7Km is a long range for ISM band communication.
But the LoRa modulation can make this point. The range is up to 8Km in the output power 100mW only.
Pls check the LoRa module RF1276 which based on Semtech SX1276.
http://www.appconwireless.com/PRODUCTS/showproduct.php?lang=en&id=21

14

YES i am in Europe.

can this module work with arduino?

i guess this can work as a client or as a server?

i have aproxematelly 30 nodes and a master node in a top of a hill , what i need is to retrieve data from each one of the nodes from the master node , can this be done with those modules?

i already purchace some Xbeess to start playing with

15

Hi, the inAir9 module from Modtronix uses the Semtech SX1276 chip, that has a very long range of up to 15km. It is available for USD15.96 (10+ qty) at http://modtronix.com/inair9.html

It is however a 3.3V module, so requires a 3.3V board.

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modtronix_com:
Hi, the inAir9 module from Modtronix uses the Semtech SX1276 chip, that has a very long range of up to 15km. It is available for USD15.96 (10+ qty) at http://modtronix.com/inair9.html

It is however a 3.3V module, so requires a 3.3V board.

Or a logic level shifter...

17

gc9n:
YES i am in Europe.

can this module work with arduino?

i guess this can work as a client or as a server?

i have aproxematelly 30 nodes and a master node in a top of a hill , what i need is to retrieve data from each one of the nodes from the master node , can this be done with those modules?

i already purchace some Xbeess to start playing with

Which country in Europe (it matters...).

The SX1276-based boards would likely fulfill your needs, if your data rate is low. If you are looking to transmit 128bytes every second, you might find you need more than one capturing device. However, they are very reasonably priced.

With a stubby antenna, in 100mW guise, you can get a module for about US$7 from a number of Chinese manufacturers.

The Modtronix inAir9 is a well-engineered device, by all accounts (although I have yet to have one in my hands) and will probably make it to the R&D stage in our next project - double the price of the Chinese units and with the issue of being 3.3V, but that is easily solved with a TTL level shifter.

Look at these articles - it is similar to what you are doing, is 868MHz and is EU-based: http://www.cooking-hacks.com/documentation/tutorials/extreme-range-lora-sx1272-module-shield-arduino-raspberry-pi-intel-galileo#step1

Don't worry about the specific modules they are using, you can use any SX1276-based module and get the same sort of results. If you used theirs, though, you would have local (Spanish) support.

We are developing for a completely different application and don't use Arduino boards and shields, but do use Atmel and ARM processors and the Arduino IDE, libraries, etc. - so, if you want a turnkey, drop-in solution at 45Euro a pop, the Xbee-multiprotocol-shield compatible solution above will definitely work, but you could do the same thing using lower-level components and a bit of protoboard for under US$20.

18

We suggest you try XBee pro. Xbee is not good option for longer distance such as 7km.
RF1276 LoRa module can fulfil the requiremnt. It is compatible with Arduino. Only four pins connect with Arduino with UART port