Why is my range less than 10m ?

XBee & XBee Gateway XBee - 802.15.4
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1

Hi

I have purchased some Series 2 XBee XB24-Z7CIT-004 modules from Sparkfun and have them working well, however the range is less than 10m.

They have PCB built antenna and were advertised as having arrange of approx 30m indoors and 120m line of sight outdoors.

Can you please explain why the range is so bad ?

To get the advertised range do I need to have an external antenna ?

Thanks in advance

2

Is the range you are achieving an indoor urban range or do you have true RF LOS conditions?

3

Yes it’s indoor urban. I was expecting 30m.

4

The 30m you are referring to indicates that it is an UP TO distance and is NOT guaranteed. The achievable distance is going to be greatly dependent on the environment and what obstructions you must get thru. Also different materials absorb RF energy at different rates resulting in different ranges.

5

I find that answer unhelpful at best.

I did ask the question about the type of antenna I have and if that was supposed to offer UP TO 30m. can you please answer that question.

I would also like to know what advantage is terms of range I would get by using an external antenna ? Can you please answer that for me.

6

Hi Wayne,

There are many reasons why range could be bad.

The documented ranges are theoretical and obviously real world differs widely.

This device works in the 2.4Ghz band in which many other devices operate. Have a read of the section “Interference in 2.4 GHz” of this article here: http://www.macworld.com/article/1140685/networking-hardware/wifi-spectrumbands.html

To answer your question “Can you please explain why the range is so bad ?” you would need to provide a spectrum analysis of the 2.4Ghz band and provide the channels you are operating on.

Either way the answer would be interference. You could try changing the channel to find one that has less interference.

To get the advertised range you would need to remove all other 2.4Ghz noise. You could use an external antenna and increase the gain but the module you have has a fixed antenna. You would need to buy another module. Saying that, the S2 modules are old. You should consider the S2C modules and if you are in the US or Australia you can also use the Pro modules which have higher power output.

The newer S2C modules also have a very basic channel scan functionality which can show you how busy each channel is.