robert heaney

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10 years, 9 months ago.

Wifi modules and distances.

Hi all,

I am about to start a project and require a wireless setup using an mbed microcrontroller. I have looked at the Vodafone 3g dongle method found here: http://mbed.org/blog/entry/Vodafone-USB-Modem-driver-released/ and this looks like it may be fine but I also looked at the internet of things pages and found them to be using wifly modules. Found here http://mbed.org/cookbook/wifly I was wondering if anyone could give a bit more detail as to the range of these. When looking at th wifly modules on websites such as cool components they state they can work up to 100 meters?? Surely if they are proper wifi modules they should work anywhere? The project i'm working on will involve units being in the middle of fields and similar places so they must be true wifi connected. Any help anyone could give would be great.

I apologise if I have any of the facts wrong but i'm very new to wireless :)

Many Thanks

Rob

2 Answers

Erik -
10 years, 9 months ago.

[quote]Surely if they are proper wifi modules they should work anywhere?[/quote] If you put your laptop in the middle of a field you also won't have wifi connection, it won't be different for those modules. There needs to be a wifi accesspoint near for them to connect with.

So it depends on the size of the fields, but if they are reasonably sized fields you won't have wifi access unless you use accesspoints with high gain directional antennas.

Then it depends on how many modules there will be in a field. If there are quite many you can use wireless modules that create one big interconnected network: So if module A and C are out of reach of each other, but they can both talk to module B, they can route their traffic via module B. And then you will need something like a basestation to connect it to whatever you want to connect it to.

And finally there is the 3G option. That should always work if you have 3G connection.

Accepted Answer
robert heaney
poster
10 years, 9 months ago.

Thanks for that. I see what you mean. The interconnected network is a good idea but not sure if there will be more than one in use yet. The 3g option looks to be best as that should give signal in most places ?? Thanks again

Yes if you are not sure there will be alot of them 3G is probably your best bet. If you have signal in a field probably depends on the 3G coverage, which you probably know better than I do ;).

There are also some long range wireless modules you can use (such as https://www.sparkfun.com/products/9411, you can also get them with a bit less range than that), although then it also depends alot on the country you are in and the local rules if they are allowed in the first place. And with such a price tag (x2 since you also need a base station to receive it) 3G will also be significantly cheaper.

posted by Erik - 30 Jun 2013

Thanks. I looked at the product suggested and it does offer outstanding range in line of sight. It is an option but I think the price just means the 3G is still the better option. Thanks again for the help.

posted by robert heaney 30 Jun 2013