Mapping the RSSI levels to it reltive distances using xbee s1 modules

Projects Networking, Protocols, and Devices
1

Dear All,

I am trying to study the possibility of deriving an estimation model the RSSI produced from the transmission of two Xbee S1 devices. my current set is as follows:

An Xbee s1 (End device) attached to xbee explorer and can monitoried by XCTU software.
An Xbee s1 (Coordinator) attached to arduino Uno device. the PWM 0 (pin #6) is attahced to pin #2 on ardunio Uno. both are running in AT mode.

the current code that I am using is simple:

int rssival;
int strength = 2;

void setup()
{
  Serial.begin(9600);
  // xbee.setSerial(Serial);
  pinMode(strength, INPUT);
  //pinMode(signalStrengthPin, INPUT);
}

void loop()
{ inByte = Serial.read();

 if (inByte == 'a'){
  {
    rssival = pulseIn(strength, HIGH, 200);
    Serial.println(rssival);
    
    
  }
  }
 
}

which actually is based on the code proposed by Notion – The all-in-one workspace for your notes, tasks, wikis, and databases.

I understand that to relate the distance to its RSSI level we have to follow several types of propagation formula depending on the environment that the signal are propagated in. propagation models like: Friss, Two-Ray Ground, Shadowing ..etc.

in my proposed model i will include these factors as much as possible.

My questions that i want ask your guidance about are the following:

  1. is the value that comes out of the presented code from arduino is in dbm? I have gone through the manual and when it describes the PWM value if activated as RSSI value the measurement could be only time pulses. (I was able to retrieve the RSSI level from AT command ATDB). I only want to make sure about this issue.

  2. if the above is not in db. I read in this url http://code.google.com/p/xbee-arduino/ that it is possible to get the RSSI of the last recieved packet when setting the node in API mode. the trouble is that if I follow the instructions in this URL http://code.google.com/p/xbee-api/wiki/XBeeConfiguration which states the configuration of the both nodes, I couldn't make chat between each other even through using two xbee explorers and different terminal programs (CoolTerm and XCTU terminal). I've followed the instructions provided but it didn't work.

Any guidance or possible help would be really appreciated.

Marwan