Regarding the propagation model, it depends on the kind of environment (e.g. indoor or outdoor, static or mobility, etc.).
Each model has always some free parameters that can be estimated theoretically or using real data. So once you have chosen a specific model for a specific environment, you will most likely get better performance if you fit your model parameters with real data. For instance, for the lognormal propagation model you get: Pr = Po - 10np log (d/do) + x Being Pr: received power Po: reference power at do do: reference distance np: path loss x: normal noise To calibrate this you set do = 1m, then measure many samples of Po at different distances d. Once you get the calibration data just fit a linear model (Po, log d) using least squares and that's it! The RSSI_VAL register to real received power is not a very accurate mapping. But if you have enough sensor you may be able to overcome the non-linearities. Cheers! Sergio On Wed, Apr 6, 2011 at 10:54 AM, AKHILA S RAO <[email protected]> wrote: > If you are reporting the values got directly from the getRSSI command, > then you need to subtract 45 to get the value of received signal in dBm. > The mapping of this power value to distance greatly depends on the > propagation environment, distance from the ground and so on. I don't think > there is any accurate general mapping. You will need to do an empirical > study to obtain the relation > > > >> Hello , >> >> I am using IRIS motes and getting RSSI values in range of some >> positive no like 30 - 60 ..... How can i map these values to some distance >> like meter or centimeter like. >> >> Please help me for these conversion. >> >> -- >> Thanks & Regards, >> Vishrut Shah >> Nirma University, >> INDIA. >> >> -- >> This message has been scanned for viruses and >> dangerous content by MailScanner, and is >> believed to be clean. >> >> _______________________________________________ >> Tinyos-help mailing list >> [email protected] >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
