[Tinyos] choosing carrier sense threshold in Mica2

[Joe Polastre]

The mica2 has software automatic gain control; it samples the noise
floor and determines where the carrier sense threshold should be. 
More information about how it works is in:

"Versatile Low Power Media Access for Sensor Networks"
Polastre, Hill, and Culler.  Sensys 2004.

-Joe


On Thu, 20 Jan 2005 13:40:14 +0100, Alejandro Santos Martínez Sala
<alejandros.martinez at upct.es> wrote:
> Hi!
> 
> I can see in RadioControlM.nc for mica2dot that carrier sense threshold is
> set
> to 0xb5.  I would like to know how  it is mapped to dBm. In MPR/MIB Mote
> User
> Manual it is said that conversion is as follows:
> Vrssi = Vbat*ADC_counts/1024
> RSSI(dBm) = -51.3Vrssi-49.2 @ 433MHz
> RSSI(dBm) = -50.0Vrssi-45.5 @ 915MHz
> 
> According to that, carrier sense threshold is set around -70 to -76 dBm. Is
> that correct?
> 
> Why has been choosen this value? Is there any particular reason?
> We want to study interference in WSN and this is an important parameter to
> obtain any conclusion.
> 
> Thanks a lot.
> Best regards from Spain
> 
>                     Alejandro
> 
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