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Topic: Wireless communication (Read 2 times) previous topic - next topic

spruce_m00se

Has anyone had any experience with these?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=200933887155&ssPageName=ADME:B:WNA:GB:3160

I would like to make a simple two way link between a unit in the basement storeroom and one in my flat, there will be approx 3 floors of reinforced concrete between them , any ideas what the chances of successful transmition would be ?

thanks in advance

wizdum


Has anyone had any experience with these?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=200933887155&ssPageName=ADME:B:WNA:GB:3160

I would like to make a simple two way link between a unit in the basement storeroom and one in my flat, there will be approx 3 floors of reinforced concrete between them , any ideas what the chances of successful transmition would be ?

thanks in advance



Your chances are pretty much zero. Concrete is full of water and metal, both of which kill RF. You could try powerline network adapters, or try mounting both radios outside (or get weather rated wireless radios, Ubiquity makes some high quality cheap ones).
"Anyone who isn't confused really doesn't understand the situation."

Electronic props for Airsoft, paintball, and laser tag -> www.nightscapetech.com

Robin2

You can get much cheaper 433Mhz transceiver modules that work with Arduinos if you want to experiment.

...R

spruce_m00se

I guess i could test the possibilities by using some pmr walkie talkies and seeing if there ismcommunication,,, would voice transmition be a good sign of data being
Possible To Send? 

I Was Going To Avoid The Cheap Ones Assuming The More Expensive would Be better ..

mauried

The ability of RF to penetrate walls and obstructions depends a lot on the frequency used.
Essentially the lower the frequency the more hope you have.
The very cheap low power radios are 433 Mhz which will have more chance than the better 2.4 Ghz radios
but experimenting is about the only way to find out.
Using walkie talkies will give you a false outcome as they generally use a much higher power output
than small data radios.
Id be inclined to use EOP (Ethernet over Power) if there are power points in both locations.

oric_dan

That price isn't too bad for 2 units plus antennas.

Based on that part# DRF4432..., as well as the specs given, I suspect these units use the Silicon Labs Si4432 transceiver chips, which are the same chips used in HopeRF RFM22 modules, about which there have been multiple threads in the Networking section.

The basic I/F is SPI, but the ebay units apparently have an RS232 to SPI chip, plus 3.3v regulator. And level-shifters???? Can't tell. You can get the RFM22 raw modules for $11-12/each, and build a DIY board, but the ebay units are not such a bad deal.

Now, these "might" work for your situation. 20dBm output = 100mW, and that's on the high end of power for such modules. Eg, most BTs and XBees (not the Pro) and nRF2401 are all only 1mW. I was able to get about 500 foot range reliably using the RFM22s, whereas the 3 low power jobbers are only good for about 10m (30 feet). And as already mentioned, 433Mhz has much much better building penetration than 2.4Ghz.


spruce_m00se

Hmm so i guess its time to hunt a sketch in the networking section

oric_dan

Did you buy those units? It looks like the auction is over. Maybe more available. I don't think you'll need a sketch for those units, just hook to Rx,Tx and go. You only should need the sketch if you have the raw SPI chips.

spruce_m00se

Yep.
They Are In The Way, Hopefully I Will Be able To Make Them Work, I Dont really want To Waste That Much Cash,
I Will try The line Of Sight On Them, Maybe Consider Using on In The Car For If Someone Triggers The Alarm While Its Down In The Basement garage.

Possibly Worth Looking into Using Them For Telemetry In My Little Rc Plane Too.

I Guess I Should Have Tried Ge5ting Two Boards To Communicate By Serial First, But Oh Well

oric_dan

Those might be heavy for the RC plane, but you might look into the raw RFM22 modules for that, as they are very small. Please report back when you test them - would be interesting to know if they successfully communicate in your situation. I imagine 2.4 Ghz would be blocked, as you need more line-of-sight, 433 Mhz should be able to go around corners better, I think. Diffraction, maybe ???

http://www.google.com/webhp?source=search_app#gs_rn=20&gs_ri=psy-ab&cp=6&gs_id=o&xhr=t&q=diffraction

Robin2

If you want telemetry in an R/C plane you should look at DelTinos http://www.deltino.com/. I don't think there is a smaller Arduino board including a wireless transceiver.

...R

spruce_m00se

interesting board robin,
although i suppose its not useful for me as my plane will be hundreds of meters away and they state a small outdoor field

i didnt look into the weight of the modules i got, as the main use will be the alarm for now, but I assume the plane will have zero problem carrying them if i do choose to use them,

Robin2

I don't know anything about long distances but (if you haven't done so) it would be well worth while emailing DavidT of Deltang - he usually replies very quickly and he's a mine of information.

...R

spruce_m00se

The boards arrived today ,
hopefully I can get them working this week and get a ping test ready.

Robin2

What boards did your get?

...R

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