On Thu, Jun 9, 2011 at 3:46 PM, Eduard GV <eduar...@gmail.com> wrote: > Hi, > > What I've learned so far from this thread is that rs_rssi (struct > ath_rx_status) is actually an SNR (not an RSSI), in dB.
RSSI has no clear definition. An SNR is a perfectly valid form of RSSI. > If SNR is computed during packet's preamble (which I presume should be > identical regardless of the modulation used for data), why for a given > tx power, I got a lower SNR when I use faster modulations? The > difference between MCS0 and MCS7 is about 6dB (same for MCS8 and > MCS15). The right way to handle this is almost certainly to dig into the driver source code and print out information about per-MCS tx power, including values read from the registers in real-time. It's a combination of logic involving calibration parameters from the EEPROM, regulatory limits, and other device-specific information. Have you tried, at all, to learn on your own? That said, your assumption that TX power will be independent of modulation is likely to be faulty. Have you heard of "Peak-to-Average Power Ratio"? It's not uncommon to reduce the maximum transmit power limit for higher modulations; check out this datasheet for the AR9160-based Ubiquiti SR-71A: http://www.ubnt.com/sr71a Dan _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
