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Hi everyone,

I started reading about this value (RSSI) that came out from pin 6 of an Xbee and decided to try getting this value to put a Dbm meter in my labview communication console between 2 xbee.

All my code related to RSSI value from the Xbee is :

Code:
int rssival;
int strengh = 52;   //Pin connected to pin 6 of XBee
......
rssival = pulseIn(strengh, LOW, 200);
......
TxBuffer[14] = rssival;
....

I made some range test and I received these value:

In the same room : 0
10 meters to 100m : 1 to 20
Not working: 70


Now the question is how to convert these numbers to Dbm????? If those are correct value I should get...


thankx
« Last Edit: July 16, 2012, 06:55:51 am by johnyboy » Logged

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Quote
All my code related to RSSI value from the Xbee is :
Not likely. For instance, strength is not defined anywhere in that snippet.

Why you are using pulseIn on that pin then remains a mystery. How RSSI relates to the time that it takes that pin to go from LOW to HIGH and back to LOW is also a mystery. As is how you think that time relates to Dbm (whatever that is).
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All my code related to RSSI value from the Xbee is :
Not likely. For instance, strength is not defined anywhere in that snippet.

Why you are using pulseIn on that pin then remains a mystery. How RSSI relates to the time that it takes that pin to go from LOW to HIGH and back to LOW is also a mystery. As is how you think that time relates to Dbm (whatever that is).


RSSI pin out of the Xbee is a PWM signal. When I am in the same room, its a 100% PWM. THan it varie from 100 to 80% when I go from 10 to 100 m. So I used pulse in to determine the PWM signal.....

CHeck this out: http://log.liminastudio.com/itp/physical-computing/measuring-xbee-signal-strength-from-the-rssi-pin
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Look at page 52 of the datasheet:
http://www.sparkfun.com/datasheets/Wireless/Zigbee/XBee-Datasheet.pdf
dB above Sensitivity - Dutycycle
10   -  41%
20   -  58%
30   -  75%

Or you could simply measure the dB values with your X-CTU Software and map them with your pulse-durations.

I hope that was helpful, Andy
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You could also low-pass filter it and read it with an ADC if measuring it directly doesn't work out.
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the number indicated by the pulse in is actually reflecting dB.  If you radios are right next to each other, it will report 0 which is -0dB.  The radios will work fine at -100 dB, the manual says a 1% packet loss. The number reported by pulsein is not a percentage, so it will exceed 100.  Make sure you use an exponential average on the number. 
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Bro mine to shard you X-ctu setting and the code??
for my
refference??
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