[Tinyos-help] Calculating RSSI in dBm locally on a mica2 mote

[Michael Schippling]

200 (decimal) is a negative number in an 8 bit signed int...about -55.
Does that make more sense for your level?
MS

Sean Casey wrote:
> Hello,
> 
> I'm working with mica2 motes and I would like to know if it's possible 
> to calculate the rssi value in dBm on the mote locally.  I had been 
> sending the rssi value to the UART and then calculating the dBm value 
> with a java program, but now I would like to calculate it locally on the 
> mote, and store it in flash.  I've attempted this and I'm not getting a 
> value in the right range. This is what I've been using:
> 
> /* Calculate the RSSI Value */
> V_RSSI = 3.0 * (RSSI_VAL/1024);
> RSSI_dBM = (int8_t) ((-50.0 * V_RSSI) - 45.5);
> 
> 
> Where V_RSSI and RSSI_VAL are of type double.  Using this I'm getting a 
> value of around 200, which is much higher than the range I'd expect.  
> Does anyone know what data types I could use to locally compute this?
> 
> Thanks for any replies.
> 
> - Sean
> 
> 
> _______________________________________________
> Tinyos-help mailing list
> Tinyos-help at Millennium.Berkeley.EDU
> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help