xbee signal losing problem

XBee & XBee Gateway XBee - 802.15.4
1

Hello,
I bought a Xbee, s1, module. it is 1mW Chip Antenna - Series 1 (802.15.4). it has built-in antenna. I tried to make a communication between PIC microcontroller and MATLAB software. It works very well at small distance e.g. 4 m but if distance becomes larger the communication signal is lost wether was inside or outside. although in the datasheet of Xbee was mentioned that the distance can be 100 m.

also, if the xbee module is moved the signal will be lost at distance larger than 3-4 m and the uart command must be resent again to return the signal [:((] .
I read the power level, it was at the highest level. I only changed the data rate to 115200 bit/sec.moreover, I tried xbees at 9600 bps but with same results which the signal of communication was lost at around 4m.

I chenged (MY) of first xbee to 1 and its (DL) to 2 and (MY) of second xbee to 2 and its (DL) to 1 that means short 16- bit unicast addressing. moreover, I increased (RR) retries but it did not work too where the problem still exists

is usually the signal between two xbee modules lost when any one of them is moved? is this normal??

is there any configuration parameter that I should change???
how can I communicate at 100m or even 50m???
I don’t know what I should do to keep the signal of communication because I’ll use xbee module for a robot ???
would anybody help me??
Thank you

2

I have not used that model. My comments might help (or not help):

  1. indoor that model is rated as ‘best case’ about 30m, so you’d need the XBee-PRO to do better. 1mW is a pretty weak signal!

  2. the chip antenna (all antenna) have a ‘signal geometry’, which means it does better in some directions than others. I don’t know what the geometry is for chip antenna, but for example a wire/whip antenna radiates power outwards perpendicular to the wire, so has very poor signal ‘up and down’.

  3. for the chip/PCB antenna, you cannot have a PCB ground-plane under the XBee. I don’t think the S1 manual covers this, but the I think the S2/Zigbee manuals do.

3

thanks lynnl, [:)]
I’m going to use xbee on a robot. it wll be outdoor. so I’ll be satisfied when the communication between both of them succeeded at 15 m , but it does not work at 5m [:((]

4

I use the PRO whenever I can, and would only use the non-PRO when I was very concerned to limit the distance to for example a single room.

Be aware that people have reported signal problems with motors nearby, due either to power supply noise/ripple added by the motor, or even radiated motor noise. One Forum user compained how their XBee ranges was great unless the motor was running, then it seemed to ‘crash’ and be short.