Xbee Pro 2SB XBP24-BZ7UIT-004 RSSI and range query


I have three of these Xbee Pro modules with the UFL antenna connection.

I have used the Seeed studio UartSBee v5.0 to connect these via USB to computers.

I am using fairly generic 10cm long UFL to RPSMA pigtail cables to connect the Xbee modules to 5 dBi 2.4 GHz omnidirectional antennas.The pigtails have the sort of cable thickness you would see in a UFL cable inside a laptop.

I have set one module to be the coordinator and the other two to be routers.

When testing using a range test in X-CTU from the coordinator to either of the routers, the best RSSI I get is -76 dBM when the modules are 30 cm apart. When 4m away but still direct line of sight, I get around -91 dBM, i.e. only 1 bar of signal on the graph. This seems very low to me.

I am unable to get a router to associate to the coordinator through a single breeze block wall. This is a distance of 3m + wall!

I have fiddled with the power level settings on all of the modules. I thought maybe the signal strength was too high and I was saturating them but reducing power does not change things.

I have also turned off all my wifi routers and disabled the wifi adapters on the computers while doing the tests - no change.

I was expecting a lot more range out of the modules to be honest, especially as they are the pro version. I am only able to use them within the same room at the moment!

I think the seeed studio UartsBee USB interface is capable of providing more than enough current at 3.3V to drive them.

I would like to be able to communicate though at least one concrete wall as I aim to use these to monitor electricity meters situated in the core of our high rise office building. I would like to use omnidirectional antennas.

Any thoughts?

My only thought is the UFL to RPSMA cable might be cheap and degrading the signal. I bought it on taobao in china :wink: Can somebody recommend a robust UFL to RPSMA pigtail?

Would the 900/868 MHz versions be capable of easily penetrating a building core concrete wall + some?

link to Xbee module I have

link to UartSBee USB interface

Your issue is that you are trying to penetrate through a steel reenforced concrete wall. Something that RF just simply has issues doing. What you are going to most likely need to do is to place a router on either side of the wall. Then your modules can talk to the module on that side of the wall and through the wall via the two routers.