Xbee pro 900 data loss

I get two Xbee 900 pro RPSMA connected on Arduino Uno and Arduino Due.

For now i get a one way communication but I will need full duplex.

All communication at 9600 baud (Xbee module, Arduino serial.begin() programmation, Arduino PC Monitoring window, PC usb COM)

I use Arduino Xbee shield on both processor (Uno and Due). I set jumper on Arduino Xbee shield to Xbee (connecting Xbee to serial arduino line)

I use “Serial.print()” Arduino command at Tx Xbee module to “talk” with the Rx Xbee module which I use the serial.available() Arduino command to rebuild the string or get the transmited data on monitoring Windows at Rx.

Get data loss between Tx and Rx ???

I try différent baud rate. 9600 work better. I work with “Quad-band Wired Cellular Antenna SMA” from Sparkfun. A dipole antenna operating at 900 MHz.

The data is well printed on the Tx monitoring Windows but in the Rx unit, stream of data miss (in Rx monitoring windows and in Rx Arduino buffered string variable).

Get a few garbage caracter and loss data at receiver.

Any sugestion ?

To close antenna (Rx & Tx) can be a problem ? (got better performance with a minimum distance between Rx & Tx)

Can I control the output power of the Xbee 900 pro ? (I check with the Digi Software X-CTU with no success)

Xbee buffer at Rx or Tx full ? (How Arduino control data flow to Xbee module ?)

Is it preferable to open a serial communication with the Xbee module in Arduino scketch instead of setting the jumper on the Arduino Xbee shield to "Xbee" and use Serial.print() command ?

My scketch do not include the Xbee.H Library, I begin no serial communication with Xbee module, I set no Tx & Rx I/O pin for Xbee. If I well understand Arduino Xbee shield note, setting jumper in "Xbee" position connect Xbee Tx & RX line to Arduino serial line.

The system as been under test for over 3 month with a distance between Rx & Tx over 2000 m and work well. But I got loss data (almost at the same place in the transmission ???) and the drop packet rate increase when the Rx & Tx are closer.

I'm a beginner with Xbee and arduino .... but i learn fast....with a little help XD


Thank for your help