On Fri, 2005-02-04 at 10:53 -0500, Sven wrote: > iwlib.c in WEXT says (in the example) > * 2) value is -54dBm. noise floor of the radio is -104dBm. > * qual->value = -54 = 202 ; range->max_qual.value = -104 = 152 > i'm confused. why is the max value the noise floor??? in Atheros chips, > given the value in dBm comes from RSSI, should max_qual.value not be > MAX_RSSI (converted into dBm)?
I think this is actually wrong... What I _think_ it should say is: * 2) level is -54dBm. noise floor of the radio is -104dBm. * qual->level = -54 = 202 ; range->max_qual.noise = -104 = 152 Noise levels _do_ change dynamically, which is something else that the drivers don't do (ahem, atmel, madwifi, and airo for starters). When you turn on your microwave, that totally screws the 2.4GHz frequency range and impacts 802.11 communications. Since the microwave is random energy, it is extra noise and therefore decreases the Signal to Noise ratio (ie, the noise value increases, say from -95dBm -> -85dBm, due to the extra energy from the microwave, while the signal may stay the same). You _always_ have a noise floor, which is the normal value where in good conditions the card can no longer distinguish the usable radio energy from background energy, but most drivers at this time use that noise floor level in the "qual.noise" field and not the "max_qual.noise" field, because they evidentally don't sample noise on each channel dynamically, or don't know how to pull that value off the card. Jean: can you give some clarification on that statement in iwlib.c? Dan _______________________________________________ NetworkManager-list mailing list NetworkManager-list@gnome.org http://mail.gnome.org/mailman/listinfo/networkmanager-list