2x input and 1x output over 2km - Zigbee?

[js]

I want to control one output with 2 inputs but output (contactor) is over 2km away ....
I don't want use gsm module!
Any solution? maybe some zigbee module .... or..?

p.s.
output must be logic controlled: if input1 occurs then go to ON and if input2 ocurrs then output must go OFF

 

[ROB2222]

RF is a very specialised subject, so you need to consult with an expert in this field, however, its extremely unlikely that you could reach this distance at 2.4GHz without resorting to using very large Antenna's.

Zigbee is a software Protocol typically running at 2.4GHz, not the means of getting the signal from one place to another. If you are planning a point to point application, then Zigbee is not ideal, as its strength lies with its ability to work in a Mesh with many other nodes, allowing data to be pased from one node to the next to finally get back to the 'Master' station. By having ten's of nodes spread out over 2km, it would be possible for the data to 'hop' from one node to the next to finally travel the 2km.

RF signals are attenuated over distance, and as a rule of thumb you can halve the distance each time you double the frequency, so a unit using 1.2GHz will transmit twice the distance as a 2.4GHz unit at the same RF Output Power & receiver sensitivity. Since ISM Bands throughout the World are strictly regulated, they are limited to a maximum amount of RF Power. In the USA it's 30dBm and in Europe is 24dBm. As a consequence longer distances are achieved at lower RF frequencies, so a 315/433MHz product will transmit much further than a 2.4Ghz product.

Depending on your location and where you want to sell your product it might be worth considering one of these lower RF frequencies all the way down to 168MHz which was recently added to the ISM Bands in Europe (not sure about USA).

Also, RF distance is affected by buildings and other RF sources, so many of the 2.4GHz distances shown by suppliers refer to "Open Field" tests, where the transmitter and receiver are located away from populated area's with line of sight between both units. In these unfair tests it can be shown that Zigbee could transmit over distances of 2km using simple PCB antenna's. However, this is not real life, so these figures are meaningless.

You need to understand the expected locations where you product is likely to be installed to understand whether its possible to achieve long distance RF communications. If you are planning to have these units installed in a Factory full of machinery and transmit across several buildings, then it's highly unlikely to work.

Although you've not stated these points in your question, my feeling is that it is going to be very difficult to achieve a distance of 2km in a practical application situated in a populated area irrespective of the ISM Band you pick even if you resort to using very large and expensive Antenna's.

I would seriously consider other methods such as WiFi (linking into the local Network) and one end and having the receiver with WiFI linking into its local Network and having the data passed over the Internet, or consider the method you have dismissed, ie GSM.

Unfortunately RF is bound by Physics, and no amount of technological progress is going to change fundemental equations !