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Topic: Xbee RSSI (Read 4068 times) previous topic - next topic

johnyboy

Jul 16, 2012, 02:41 am Last Edit: Jul 16, 2012, 01:55 pm by johnyboy Reason: 1
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: [Select]

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

PaulS

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).

johnyboy


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).



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

guest1102

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

smeezekitty

You could also low-pass filter it and read it with an ADC if measuring it directly doesn't work out.
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

fnsnoop

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. 

sataman

Bro mine to shard you X-ctu setting and the code??
for my
refference??

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